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Bolte CE, Phannareth T, Zavala-Paez M, Sutara BN, Can MF, Fitzpatrick MC, Holliday JA, Keller SR, Hamilton JA. Genomic insights into hybrid zone formation: The role of climate, landscape, and demography in the emergence of a novel hybrid lineage. Mol Ecol 2024; 33:e17430. [PMID: 38867593 DOI: 10.1111/mec.17430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 06/14/2024]
Abstract
Population demographic changes, alongside landscape, geographic and climate heterogeneity, can influence the timing, stability and extent of introgression where species hybridise. Thus, quantifying interactions across diverged lineages, and the relative contributions of interspecific genetic exchange and selection to divergence at the genome-wide level is needed to better understand the drivers of hybrid zone formation and maintenance. We used seven latitudinally arrayed transects to quantify the contributions of climate, geography and landscape features to broad patterns of genetic structure across the hybrid zone of Populus trichocarpa and P. balsamifera and evaluated the demographic context of hybridisation over time. We found genetic structure differed among the seven transects. While ancestry was structured by climate, landscape features influenced gene flow dynamics. Demographic models indicated a secondary contact event may have influenced contemporary hybrid zone formation with the origin of a putative hybrid lineage that inhabits regions with higher aridity than either of the ancestral groups. Phylogenetic relationships based on chloroplast genomes support the origin of this hybrid lineage inferred from demographic models based on the nuclear data. Our results point towards the importance of climate and landscape patterns in structuring the contact zones between P. trichocarpa and P. balsamifera and emphasise the value whole genome sequencing can have to advancing our understanding of how neutral processes influence divergence across space and time.
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Affiliation(s)
- Constance E Bolte
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Tommy Phannareth
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, Virginia, USA
| | - Michelle Zavala-Paez
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Brianna N Sutara
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | | | - Matthew C Fitzpatrick
- Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, Maryland, USA
| | - Jason A Holliday
- Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, Virginia, USA
| | - Stephen R Keller
- Department of Plant Biology, University of Vermont, Burlington, Vermont, USA
| | - Jill A Hamilton
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania, USA
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2
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Setsuko S, Sugai K, Tamaki I, Hayama K, Kato H. Ecotype variation in the endemic tree Callicarpa subpubescens on small oceanic islands: genetic, phenotypic, and environmental insights. Heredity (Edinb) 2024; 132:309-319. [PMID: 38714843 PMCID: PMC11166659 DOI: 10.1038/s41437-024-00684-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 04/11/2024] [Accepted: 04/14/2024] [Indexed: 06/13/2024] Open
Abstract
Callicarpa subpubescens, endemic to the Ogasawara Islands, is suggested to have multiple ecotypes in the Hahajima Islands, specifically in the central part of the Ogasawara Islands. In this study, associations between genetic groups and spatial distribution, habitat, leaf morphology, size structure, and flowering time of each genetic group were investigated on Hahajima and the satellite Imoutojima Islands. Genetic groups were identified using EST-SSR markers, revealing four ecotypes named based on morphological features: Dwarf (D), Glabrescent (G), Tall (T), and Middle (M), with M being a result of the hybridization of G and T. Ecotype D, adapted to dry environments, is characterized by small tree size, dense thick leaves with abundant hairs, and is distributed in dry scrub. Ecotype G, adapted to understory of mesic forests, lacks leaf hairs. Ecotype T, adapted to the canopy of mesic forests, has hairy leaves and is tall in tree height. Ecotype M, adapted to the canopy of mesic scrub or edges of mesic forests, has hairy leaves but with a shorter tree height than ecotype T. Flowering peaks differed among all ecotype pairs except G and M, but the flowering times more or less overlapped among all ecotypes, suggesting that pre-mating isolation among ecotypes is not perfect. Post-mating isolation is considered absent, as there were no differences in the results, germination, and survival rates of one-year seedlings among inter- and intra-ecotype crossings. The existence of such ecotypes provides valuable insights into the ongoing speciation processes adapting to the oceanic island environments.
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Affiliation(s)
- Suzuki Setsuko
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute, Forest Research and Management Organization, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Kyoko Sugai
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-cho, Matsue, Shimane, 690-8504, Japan
| | - Ichiro Tamaki
- Gifu Field Science Center, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Kayo Hayama
- Ogasawara Environmental Planning Laboratory, Motochi, Ogasawara, Tokyo, 100-2211, Japan
| | - Hidetoshi Kato
- Makino Herbarium, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397, Japan
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3
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Fetter KC, Keller SR. Admixture mapping and selection scans identify genomic regions associated with stomatal patterning and disease resistance in hybrid poplars. Ecol Evol 2023; 13:e10579. [PMID: 37881228 PMCID: PMC10597741 DOI: 10.1002/ece3.10579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 09/18/2023] [Accepted: 09/21/2023] [Indexed: 10/27/2023] Open
Abstract
Variation in fitness components can be linked in some cases to variation in key traits. Metric traits that lie at the intersection of development, defense, and ecological interactions may be expected to experience environmental selection, informing our understanding of evolutionary and ecological processes. Here, we use quantitative genetic and population genomic methods to investigate disease dynamics in hybrid and non-hybrid populations. We focus our investigation on morphological and ecophysiological traits which inform our understanding of physiology, growth, and defense against a pathogen. In particular, we investigate stomata, microscopic pores on the surface of a leaf that regulate gas exchange during photosynthesis and are sites of entry for various plant pathogens. Stomatal patterning traits were highly predictive of disease risk. Admixture mapping identified a polygenic basis of disease resistance. Candidate genes for stomatal and disease resistance map to the same genomic regions and experienced positive selection. Genes with functions to guard cell homeostasis, the plant immune system, components of constitutive defenses, and growth-related transcription factors were identified. Our results indicate positive selection acted on candidate genes for stomatal patterning and disease resistance, potentially acting in concert to structure their variation in naturally formed backcrossing hybrid populations.
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Affiliation(s)
- Karl C. Fetter
- Department of Plant BiologyUniversity of VermontBurlingtonVermontUSA
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsConnecticutUSA
| | - Stephen R. Keller
- Department of Plant BiologyUniversity of VermontBurlingtonVermontUSA
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4
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Bock DG, Cai Z, Elphinstone C, González-Segovia E, Hirabayashi K, Huang K, Keais GL, Kim A, Owens GL, Rieseberg LH. Genomics of plant speciation. PLANT COMMUNICATIONS 2023; 4:100599. [PMID: 37050879 PMCID: PMC10504567 DOI: 10.1016/j.xplc.2023.100599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/21/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
Studies of plants have been instrumental for revealing how new species originate. For several decades, botanical research has complemented and, in some cases, challenged concepts on speciation developed via the study of other organisms while also revealing additional ways in which species can form. Now, the ability to sequence genomes at an unprecedented pace and scale has allowed biologists to settle decades-long debates and tackle other emerging challenges in speciation research. Here, we review these recent genome-enabled developments in plant speciation. We discuss complications related to identification of reproductive isolation (RI) loci using analyses of the landscape of genomic divergence and highlight the important role that structural variants have in speciation, as increasingly revealed by new sequencing technologies. Further, we review how genomics has advanced what we know of some routes to new species formation, like hybridization or whole-genome duplication, while casting doubt on others, like population bottlenecks and genetic drift. While genomics can fast-track identification of genes and mutations that confer RI, we emphasize that follow-up molecular and field experiments remain critical. Nonetheless, genomics has clarified the outsized role of ancient variants rather than new mutations, particularly early during speciation. We conclude by highlighting promising avenues of future study. These include expanding what we know so far about the role of epigenetic and structural changes during speciation, broadening the scope and taxonomic breadth of plant speciation genomics studies, and synthesizing information from extensive genomic data that have already been generated by the plant speciation community.
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Affiliation(s)
- Dan G Bock
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Zhe Cai
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Cassandra Elphinstone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Eric González-Segovia
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | | | - Kaichi Huang
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Graeme L Keais
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Amy Kim
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
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5
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Shang H, Field DL, Paun O, Rendón-Anaya M, Hess J, Vogl C, Liu J, Ingvarsson PK, Lexer C, Leroy T. Drivers of genomic landscapes of differentiation across a Populus divergence gradient. Mol Ecol 2023; 32:4348-4361. [PMID: 37271855 DOI: 10.1111/mec.17034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/20/2023] [Accepted: 05/23/2023] [Indexed: 06/06/2023]
Abstract
Speciation, the continuous process by which new species form, is often investigated by looking at the variation of nucleotide diversity and differentiation across the genome (hereafter genomic landscapes). A key challenge lies in how to determine the main evolutionary forces at play shaping these patterns. One promising strategy, albeit little used to date, is to comparatively investigate these genomic landscapes as progression through time by using a series of species pairs along a divergence gradient. Here, we resequenced 201 whole-genomes from eight closely related Populus species, with pairs of species at different stages along the divergence gradient to learn more about speciation processes. Using population structure and ancestry analyses, we document extensive introgression between some species pairs, especially those with parapatric distributions. We further investigate genomic landscapes, focusing on within-species (i.e. nucleotide diversity and recombination rate) and among-species (i.e. relative and absolute divergence) summary statistics of diversity and divergence. We observe relatively conserved patterns of genomic divergence across species pairs. Independent of the stage across the divergence gradient, we find support for signatures of linked selection (i.e. the interaction between natural selection and genetic linkage) in shaping these genomic landscapes, along with gene flow and standing genetic variation. We highlight the importance of investigating genomic patterns on multiple species across a divergence gradient and discuss prospects to better understand the evolutionary forces shaping the genomic landscapes of diversity and differentiation.
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Affiliation(s)
- Huiying Shang
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
- Vienna Graduate School of Population Genetics, Vienna, Austria
- Xi'an Botanical Garden of Shaanxi Province, Institute of Botany of Shaanxi Province, Xi'an, China
| | - David L Field
- School of Science, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Ovidiu Paun
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Martha Rendón-Anaya
- Department of Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Jaqueline Hess
- Helmholtz Centre for Environmental Research, Halle (Saale), Germany
| | - Claus Vogl
- Department of Biomedical Sciences, Vetmeduni Vienna, Vienna, Austria
| | - Jianquan Liu
- Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, China
| | - Pär K Ingvarsson
- Department of Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Thibault Leroy
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
- GenPhySE, INRAE, INP, ENVT, Université de Toulouse, Castanet-Tolosan, France
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6
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Li Y, Wang D, Wang W, Yang W, Gao J, Zhang W, Shan L, Kang M, Chen Y, Ma T. A chromosome-level Populus qiongdaoensis genome assembly provides insights into tropical adaptation and a cryptic turnover of sex determination. Mol Ecol 2023; 32:1366-1380. [PMID: 35712997 DOI: 10.1111/mec.16566] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/24/2022] [Accepted: 06/10/2022] [Indexed: 01/17/2023]
Abstract
Populus species have long been used as model organisms to study the adaptability of trees and the evolution of sex chromosomes. As a species belonging to the section Populus and limited to tropical areas, the P. qiongdaoensis genome contains important information for tropical poplar studies and protection. Here, we report a chromosome-level genome assembly and annotation of a female P. qiongdaoensis. Gene family clustering, positive selection detection and historical reconstruction of population dynamics revealed the tropical adaptation of P. qiongdaoensis, and showed convergent evolution with another tropical poplar, P. ilicifolia, at the molecular level, especially on some functional genes (e.g., PIF3 and PIL1). In addition, we also identified a ZW sex determination system on chromosome 19 of P. qiongdaoensis, and inferred that it seems to have a similar sex determination mechanism to other poplars, controlled by a type-A cytokinin response regulator (RR) gene. However, comparison and phylogenetic analysis of the sex determination regions confirmed a cryptic sex turnover event in the section Populus, which may be caused by the translocation and duplication of the RR gene driven by Helitron-like transposable elements. Our study provides new insights into the environmental adaptation and sex chromosome evolution of poplars, and emphasizes the importance of using long read sequencing in ecological and evolutionary inferences of plants.
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Affiliation(s)
- Yiling Li
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Deyan Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Weiwei Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Wenlu Yang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Jinwen Gao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Wenyan Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Lanxing Shan
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Minghui Kang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Yang Chen
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
| | - Tao Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station, College of Life Sciences, Sichuan University, Chengdu, China
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7
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Carrell AA, Hicks BB, Sidelinger E, Johnston ER, Jawdy SS, Clark MM, Klingeman DM, Cregger MA. Nitrogen addition alters soil fungal communities, but root fungal communities are resistant to change. Front Microbiol 2023; 13:1033631. [PMID: 36762095 PMCID: PMC9905728 DOI: 10.3389/fmicb.2022.1033631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 12/16/2022] [Indexed: 01/26/2023] Open
Abstract
Plants are colonized by numerous microorganisms serving important symbiotic functions that are vital to plant growth and success. Understanding and harnessing these interactions will be useful in both managed and natural ecosystems faced with global change, but it is still unclear how variation in environmental conditions and soils influence the trajectory of these interactions. In this study, we examine how nitrogen addition alters plant-fungal interactions within two species of Populus - Populus deltoides and P. trichocarpa. In this experiment, we manipulated plant host, starting soil (native vs. away for each tree species), and nitrogen addition in a fully factorial replicated design. After ~10 weeks of growth, we destructively harvested the plants and characterized plant growth factors and the soil and root endosphere fungal communities using targeted amplicon sequencing of the ITS2 gene region. Overall, we found nitrogen addition altered plant growth factors, e.g., plant height, chlorophyll density, and plant N content. Interestingly, nitrogen addition resulted in a lower fungal alpha diversity in soils but not plant roots. Further, there was an interactive effect of tree species, soil origin, and nitrogen addition on soil fungal community composition. Starting soils collected from Oregon and West Virginia were dominated by the ectomycorrhizal fungi Inocybe (55.8% relative abundance), but interestingly when P. deltoides was grown in its native West Virginia soil, the roots selected for a high abundance of the arbuscular mycorrhizal fungi, Rhizophagus. These results highlight the importance of soil origin and plant species on establishing plant-fungal interactions.
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Affiliation(s)
- Alyssa A. Carrell
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Brittany B. Hicks
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Emilie Sidelinger
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC, United States
| | - Eric R. Johnston
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Sara S. Jawdy
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Miranda M. Clark
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Dawn M. Klingeman
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Melissa A. Cregger
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States,*Correspondence: Melissa A. Cregger ✉
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8
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Peng Y, Derks MFL, Groenen MAM, Zhao Y, Bosse M. Distinct traces of mixed ancestry in western commercial pig genomes following gene flow from Chinese indigenous breeds. Front Genet 2023; 13:1070783. [PMID: 36712875 PMCID: PMC9880450 DOI: 10.3389/fgene.2022.1070783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 12/19/2022] [Indexed: 01/15/2023] Open
Abstract
Studying gene flow between different livestock breeds will benefit the discovery of genes related to production traits and provide insight into human historical breeding. Chinese pigs have played an indispensable role in the breeding of Western commercial pigs. However, the differences in the timing and volume of the contribution of pigs from different Chinese regions to Western pigs are not yet apparent. In this paper, we combine the whole-genome sequencing data of 592 pigs from different studies and illustrate patterns of gene flow from Chinese pigs into Western commercial pigs. We describe introgression patterns from four distinct Chinese indigenous groups into five Western commercial groups. There were considerable differences in the number and length of the putative introgressed segments from Chinese pig groups that contributed to Western commercial pig breeds. The contribution of pigs from different Chinese geographical locations to a given western commercial breed varied more than that from a specific Chinese pig group to different Western commercial breeds, implying admixture within Europe after introgression. Within different Western commercial lines from the same breed, the introgression patterns from a given Chinese pig group seemed highly conserved, suggesting that introgression of Chinese pigs into Western commercial pig breeds mainly occurred at an early stage of breed formation. Finally, based on analyses of introgression signals, allele frequencies, and selection footprints, we identified a ∼2.65 Mb Chinese-derived haplotype under selection in Duroc pigs (CHR14: 95.68-98.33 Mb). Functional and phenotypic studies demonstrate that this PRKG1 haplotype is related to backfat and loin depth in Duroc pigs. Overall, we demonstrate that the introgression history of domestic pigs is complex and that Western commercial pigs contain distinct traces of mixed ancestry, likely derived from various Chinese pig breeds.
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Affiliation(s)
- Yebo Peng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Martijn FL Derks
- Animal Breeding and Genomics, Wageningen University & Research, Wageningen, Netherlands
- Topigs Norsvin Research Center, Beuningen, Netherlands
| | - Martien AM Groenen
- Animal Breeding and Genomics, Wageningen University & Research, Wageningen, Netherlands
| | - Yiqiang Zhao
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Mirte Bosse
- Animal Breeding and Genomics, Wageningen University & Research, Wageningen, Netherlands
- Amsterdam Insitute of Life and Environment (A-Life), VU University Amsterdam, Amsterdam, Netherlands
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9
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vonHoldt BM, Brzeski KE, Aardema ML, Schell CJ, Rutledge LY, Fain SR, Shutt AC, Linderholm A, Murphy WJ. Persistence and expansion of cryptic endangered red wolf genomic ancestry along the American Gulf coast. Mol Ecol 2022; 31:5440-5454. [PMID: 34585803 DOI: 10.1111/mec.16200] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 09/03/2021] [Accepted: 09/22/2021] [Indexed: 12/24/2022]
Abstract
Admixture and introgression play a critical role in adaptation and genetic rescue that has only recently gained a deeper appreciation. Here, we explored the geographical and genomic landscape of cryptic ancestry of the endangered red wolf that persists within the genome of a ubiquitous sister taxon, the coyote, all while the red wolf has been extinct in the wild since the early 1980s. We assessed admixture across 120,621 single nucleotiode polymorphism (SNP) loci genotyped in 293 canid genomes. We found support for increased red wolf ancestry along a west-to-east gradient across the southern United States associated with historical admixture in the past 100 years. Southwestern Louisiana and southeastern Texas, the geographical zone where the last red wolves were known prior to extinction in the wild, contained the highest and oldest levels of red wolf ancestry. Further, given the paucity of inferences based on chromosome types, we compared patterns of ancestry on the X chromosome and autosomes. We additionally aimed to explore the relationship between admixture timing and recombination rate variation to investigate gene flow events. We found that X-linked regions of low recombination rates were depleted of introgression, relative to the autosomes, consistent with the large X effect and enrichment with loci involved in maintaining reproductive isolation. Recombination rate was positively correlated with red wolf ancestry across coyote genomes, consistent with theoretical predictions. The geographical and genomic extent of cryptic red wolf ancestry can provide novel genomic resources for recovery plans targeting the conservation of the endangered red wolf.
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Affiliation(s)
- Bridgett M vonHoldt
- Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Kristin E Brzeski
- College of Forest Resources and Environment Science, Michigan Technological University, Houghton, Michigan, USA
| | - Matthew L Aardema
- Department of Biology, Montclair State University, Montclair, New Jersey, USA.,Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York, USA
| | - Christopher J Schell
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, California, USA
| | - Linda Y Rutledge
- Biology Department, Trent University, Peterborough, Ontario, Canada
| | - Steven R Fain
- USFWS, Clark R. Bavin National Forensics Laboratory, Ashland, Oregon, USA
| | | | - Anna Linderholm
- Department of Anthropology, Texas A&M University, College Station, Texas, USA
| | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
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10
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VanWallendael A, Lowry DB, Hamilton JA. One hundred years into the study of ecotypes, new advances are being made through large-scale field experiments in perennial plant systems. CURRENT OPINION IN PLANT BIOLOGY 2022; 66:102152. [PMID: 35065527 DOI: 10.1016/j.pbi.2021.102152] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/31/2021] [Accepted: 11/03/2021] [Indexed: 06/14/2023]
Abstract
A hundred years after Turesson first clearly described how locally adaptive variation is distributed within species, plant biologists are making major breakthroughs in our understanding of mechanisms underlying adaptation from local populations to the scale of continents. Although the genetics of local adaptation has typically been studied in smaller reciprocal transplant experiments, it is now being evaluated with whole genomes in large-scale networks of common garden experiments with perennial switchgrass and poplar trees. These studies support the hypothesis that a complex combination of loci, both with and without adaptive trade-offs, underlies local adaptation and that hybridization and adaptive introgression play a key role in the evolution of these species. Future studies incorporating high-throughput phenotyping, gene expression, and modeling will be used to predict responses of these species to climate change.
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Affiliation(s)
- Acer VanWallendael
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA; Department of Energy Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA; Program in Ecology, Evolution, and Behaviour, Michigan State University, East Lansing, MI, 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA; Department of Energy Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA; Program in Ecology, Evolution, and Behaviour, Michigan State University, East Lansing, MI, 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA.
| | - Jill A Hamilton
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, 16801, USA
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11
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Cardoni S, Piredda R, Denk T, Grimm GW, Papageorgiou AC, Schulze E, Scoppola A, Salehi Shanjani P, Suyama Y, Tomaru N, Worth JRP, Cosimo Simeone M. 5S-IGS rDNA in wind-pollinated trees (Fagus L.) encapsulates 55 million years of reticulate evolution and hybrid origins of modern species. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 109:909-926. [PMID: 34808015 PMCID: PMC9299691 DOI: 10.1111/tpj.15601] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 11/02/2021] [Accepted: 11/18/2021] [Indexed: 05/31/2023]
Abstract
Standard models of plant speciation assume strictly dichotomous genealogies in which a species, the ancestor, is replaced by two offspring species. The reality in wind-pollinated trees with long evolutionary histories is more complex: species evolve from other species through isolation when genetic drift exceeds gene flow; lineage mixing can give rise to new species (hybrid taxa such as nothospecies and allopolyploids). The multi-copy, potentially multi-locus 5S rDNA is one of few gene regions conserving signal from dichotomous and reticulate evolutionary processes down to the level of intra-genomic recombination. Therefore, it can provide unique insights into the dynamic speciation processes of lineages that diversified tens of millions of years ago. Here, we provide the first high-throughput sequencing (HTS) of the 5S intergenic spacers (5S-IGS) for a lineage of wind-pollinated subtropical to temperate trees, the Fagus crenata - F. sylvatica s.l. lineage, and its distant relative F. japonica. The observed 4963 unique 5S-IGS variants reflect a complex history of hybrid origins, lineage sorting, mixing via secondary gene flow, and intra-genomic competition between two or more paralogous-homoeologous 5S rDNA lineages. We show that modern species are genetic mosaics and represent a striking case of ongoing reticulate evolution during the past 55 million years.
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Affiliation(s)
- Simone Cardoni
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
| | - Roberta Piredda
- Department of Veterinary MedicineUniversity of Bari ‘Aldo Moro’Valenzano70010Italy
| | - Thomas Denk
- Swedish Museum of Natural HistoryStockholm10405Sweden
| | | | | | | | - Anna Scoppola
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
| | - Parvin Salehi Shanjani
- Natural Resources Gene Bank, Research Institute of Forests and RangelandsAgricultural Research, Education and Extension OrganizationTehranIran
| | - Yoshihisa Suyama
- Graduate School of Agricultural ScienceTohoku UniversityOsakiMiyagi989‐6711Japan
| | - Nobuhiro Tomaru
- Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaAichi464‐8601Japan
| | - James R. P. Worth
- Ecological Genetics LaboratoryForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Marco Cosimo Simeone
- Department of Agricultural and Forestry Science (DAFNE)Università degli studi della TusciaViterbo01100Italy
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12
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Jurca M, Sjölander J, Ibáñez C, Matrosova A, Johansson M, Kozarewa I, Takata N, Bakó L, Webb AAR, Israelsson-Nordström M, Eriksson ME. ZEITLUPE Promotes ABA-Induced Stomatal Closure in Arabidopsis and Populus. FRONTIERS IN PLANT SCIENCE 2022; 13:829121. [PMID: 35310670 PMCID: PMC8924544 DOI: 10.3389/fpls.2022.829121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 01/26/2022] [Indexed: 05/22/2023]
Abstract
Plants balance water availability with gas exchange and photosynthesis by controlling stomatal aperture. This control is regulated in part by the circadian clock, but it remains unclear how signalling pathways of daily rhythms are integrated into stress responses. The serine/threonine protein kinase OPEN STOMATA 1 (OST1) contributes to the regulation of stomatal closure via activation of S-type anion channels. OST1 also mediates gene regulation in response to ABA/drought stress. We show that ZEITLUPE (ZTL), a blue light photoreceptor and clock component, also regulates ABA-induced stomatal closure in Arabidopsis thaliana, establishing a link between clock and ABA-signalling pathways. ZTL sustains expression of OST1 and ABA-signalling genes. Stomatal closure in response to ABA is reduced in ztl mutants, which maintain wider stomatal apertures and show higher rates of gas exchange and water loss than wild-type plants. Detached rosette leaf assays revealed a stronger water loss phenotype in ztl-3, ost1-3 double mutants, indicating that ZTL and OST1 contributed synergistically to the control of stomatal aperture. Experimental studies of Populus sp., revealed that ZTL regulated the circadian clock and stomata, indicating ZTL function was similar in these trees and Arabidopsis. PSEUDO-RESPONSE REGULATOR 5 (PRR5), a known target of ZTL, affects ABA-induced responses, including stomatal regulation. Like ZTL, PRR5 interacted physically with OST1 and contributed to the integration of ABA responses with circadian clock signalling. This suggests a novel mechanism whereby the PRR proteins-which are expressed from dawn to dusk-interact with OST1 to mediate ABA-dependent plant responses to reduce water loss in time of stress.
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Affiliation(s)
- Manuela Jurca
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Johan Sjölander
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Cristian Ibáñez
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
- Departamento de Biología Universidad de La Serena, La Serena, Chile
| | - Anastasia Matrosova
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Mikael Johansson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
- RNA Biology and Molecular Physiology, Faculty for Biology, Bielefeld University, Bielefeld, Germany
| | - Iwanka Kozarewa
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Naoki Takata
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
- Forest Bio-Research Center, Forestry and Forest Products Research Institute, Hitachi, Japan
| | - Laszlo Bakó
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Alex A. R. Webb
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Maria Israelsson-Nordström
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Maria E. Eriksson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Maria E. Eriksson,
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13
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O'Donnell ST, Fitz-Gibbon ST, Sork VL. Ancient Introgression Between Distantly Related White Oaks (Quercus sect. Quercus) Shows Evidence of Climate-Associated Asymmetric Gene Exchange. J Hered 2021; 112:663-670. [PMID: 34508641 DOI: 10.1093/jhered/esab053] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 09/10/2021] [Indexed: 12/14/2022] Open
Abstract
Ancient introgression can be an important source of genetic variation that shapes the evolution and diversification of many taxa. Here, we estimate the timing, direction, and extent of gene flow between two distantly related oak species in the same section (Quercus sect. Quercus). We estimated these demographic events using genotyping by sequencing data, which generated 25 702 single nucleotide polymorphisms for 24 individuals of California scrub oak (Quercus berberidifolia) and 23 individuals of Engelmann oak (Quercus engelmannii). We tested several scenarios involving gene flow between these species using the diffusion approximation-based population genetic inference framework and model-testing approach of the Python package DaDi. We found that the most likely demographic scenario includes a bottleneck in Q. engelmannii that coincides with asymmetric gene flow from Q. berberidifolia into Q. engelmannii. Given that the timing of this gene flow coincides with the advent of a Mediterranean-type climate in the California Floristic Province, we propose that changing precipitation patterns and seasonality may have favored the introgression of climate-associated genes from the endemic into the non-endemic California oak.
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Affiliation(s)
- Scott T O'Donnell
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Sorel T Fitz-Gibbon
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Victoria L Sork
- Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
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14
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Janzen T, Miró Pina V. Estimating the time since admixture from phased and unphased molecular data. Mol Ecol Resour 2021; 22:908-926. [PMID: 34599646 PMCID: PMC9291888 DOI: 10.1111/1755-0998.13519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 11/26/2022]
Abstract
After admixture, recombination breaks down genomic blocks of contiguous ancestry. The breakdown of these blocks forms a new “molecular clock” that ticks at a much faster rate than the mutation clock, enabling accurate dating of admixture events in the recent past. However, existing theory on the breakdown of these blocks, or the accumulation of delineations between blocks, so‐called “junctions”, has mostly been limited to using regularly spaced markers on phased data. Here, we present an extension to the theory of junctions using the ancestral recombination graph that describes the expected number of junctions for any distribution of markers along the genome. Furthermore, we provide a new framework to infer the time since admixture using unphased data. We demonstrate both the phased and unphased methods on simulated data and show that our new extensions have improved accuracy with respect to previous methods, especially for smaller population sizes and more ancient admixture times. Lastly, we demonstrate the applicability of our method on three empirical data sets, including labcrosses of yeast (Saccharomyces cerevisae) and two case studies of hybridization in swordtail fish and Populus trees.
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Affiliation(s)
- Thijs Janzen
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.,Carl von Ossietzky University, Oldenburg, Germany
| | - Verónica Miró Pina
- Instituto de Investigaciones en Matemáticas Aplicadas y Sistemas (IIMAS), Universidad Nacional Autónoma de México (UNAM), México City, México.,Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
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15
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Rendón-Anaya M, Wilson J, Sveinsson S, Fedorkov A, Cottrell J, Bailey MES, Ruņģis D, Lexer C, Jansson S, Robinson KM, Street NR, Ingvarsson PK. Adaptive introgression facilitate adaptation to high latitudes in European aspen (Populus tremula L.). Mol Biol Evol 2021; 38:5034-5050. [PMID: 34329481 PMCID: PMC8557470 DOI: 10.1093/molbev/msab229] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Understanding local adaptation has become a key research area given the ongoing climate challenge and the concomitant requirement to conserve genetic resources. Perennial plants, such as forest trees, are good models to study local adaptation given their wide geographic distribution, largely outcrossing mating systems, and demographic histories. We evaluated signatures of local adaptation in European aspen (Populus tremula) across Europe by means of whole-genome resequencing of a collection of 411 individual trees. We dissected admixture patterns between aspen lineages and observed a strong genomic mosaicism in Scandinavian trees, evidencing different colonization trajectories into the peninsula from Russia, Central and Western Europe. As a consequence of the secondary contacts between populations after the last glacial maximum, we detected an adaptive introgression event in a genome region of ∼500 kb in chromosome 10, harboring a large-effect locus that has previously been shown to contribute to adaptation to the short growing seasons characteristic of Northern Scandinavia. Demographic simulations and ancestry inference suggest an Eastern origin—probably Russian—of the adaptive Nordic allele which nowadays is present in a homozygous state at the north of Scandinavia. The strength of introgression and positive selection signatures in this region is a unique feature in the genome. Furthermore, we detected signals of balancing selection, shared across regional populations, that highlight the importance of standing variation as a primary source of alleles that facilitate local adaptation. Our results, therefore, emphasize the importance of migration–selection balance underlying the genetic architecture of key adaptive quantitative traits.
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Affiliation(s)
- Martha Rendón-Anaya
- Linnean Centre for Plant Biology, Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden
| | - Jonathan Wilson
- Linnean Centre for Plant Biology, Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden
| | | | - Aleksey Fedorkov
- Institute of Biology, Komi Science Center, Russian Academy of Sciences, Syktyvkar, Russia
| | - Joan Cottrell
- Forest Research, Northern Research Station, Roslin, UK
| | - Mark E S Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Dainis Ruņģis
- Genetic Resource Centre, Latvian State Forest Research Institute "Silava", LV2169 Salaspils, Latvia
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Stefan Jansson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Kathryn M Robinson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Nathaniel R Street
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Pär K Ingvarsson
- Linnean Centre for Plant Biology, Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden
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16
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Pazhenkova EA, Lukhtanov VA. Genomic introgression from a distant congener in the Levant fritillary butterfly, Melitaea acentria. Mol Ecol 2021; 30:4819-4832. [PMID: 34288183 DOI: 10.1111/mec.16085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 12/12/2022]
Abstract
Introgressive hybridization is more common in nature than previously thought, and its role and creative power in evolution is hotly discussed but not completely understood. Introgression occurs more frequently in sympatry between recently diverged taxa, or when the speciation process has not yet been completed. However, there are relatively few documented cases of hybridization that erodes reproductive barriers between distantly related species. Here, we use whole genome and mitochondrial data to examine how introgression from a distant congener affects pattern of genetic differentiation in the Levant fritillary butterfly Melitaea acentria. We show that this local taxon has evolved as a peripatric geographic isolate of the widespread Melitaea persea, and that there has been significant unidirectional gene flow from the sympatric, nonclosely related Melitaea didyma to M. acentria. We found direct evidence of ongoing sporadic hybridization between M. didyma and M. acentria, which are separated by at least 5 million years of independent evolution. Elevated differentiation and lower level of introgression on the sex Z chromosome compared to autosomes suggest that the Z chromosome has accumulated loci acting as intrinsic postzygotic barriers. Our results show that introgression from M. didyma has been an additional source of nucleotide diversity in the M. acentria population, providing material for drift and selection.
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Affiliation(s)
- Elena A Pazhenkova
- Department of Entomology, St. Petersburg State University, St. Petersburg, Russia.,Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia
| | - Vladimir A Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia
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17
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Goulet-Scott BE, Garner AG, Hopkins R. Genomic analyses overturn two long-standing homoploid hybrid speciation hypotheses. Evolution 2021; 75:1699-1710. [PMID: 34101168 DOI: 10.1111/evo.14279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/27/2021] [Accepted: 05/11/2021] [Indexed: 01/21/2023]
Abstract
The importance of hybridization in generating biological diversity has been historically controversial. Previously, inference about hybridization was limited by dependence on morphological data; with the advent of the next-generation sequencing tools for nonmodel organisms, the evolutionary significance of hybridization is more evident. Here, we test classic hypotheses of hybrid origins of two species in the Phlox pilosa complex. Morphological intermediacy motivated the hypotheses that Phlox amoena lighthipei and Phlox pilosa deamii were independent homoploid hybrid lineages derived from P. amoena amoena and P. pilosa pilosa. We use double-digest restriction site-associated DNA sequencing of individuals from throughout the range of these taxa to conduct the most thorough analysis of evolutionary history in this system to date. Surprisingly, we find no support for the hybrid origin of P. pilosa deamii or P. amoena lighthipei. Our data do identify a history of admixture in individuals collected at a contemporary hybrid zone between the putative parent lineages. We show that three very different evolutionary histories, only one of which involves hybrid origin, have produced intermediate or recombinant morphological traits between P. amoena amoena and P. pilosa pilosa. Although morphological data are still an efficient means of generating hypotheses about past gene flow, genomic data are now the standard of evidence for elucidating evolutionary history.
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Affiliation(s)
- Benjamin E Goulet-Scott
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138
| | - Austin G Garner
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138.,Arnold Arboretum of Harvard University, Boston, Massachusetts, 02131
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18
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Gower G, Picazo PI, Fumagalli M, Racimo F. Detecting adaptive introgression in human evolution using convolutional neural networks. eLife 2021; 10:64669. [PMID: 34032215 PMCID: PMC8192126 DOI: 10.7554/elife.64669] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 05/24/2021] [Indexed: 01/10/2023] Open
Abstract
Studies in a variety of species have shown evidence for positively selected variants introduced into a population via introgression from another, distantly related population—a process known as adaptive introgression. However, there are few explicit frameworks for jointly modelling introgression and positive selection, in order to detect these variants using genomic sequence data. Here, we develop an approach based on convolutional neural networks (CNNs). CNNs do not require the specification of an analytical model of allele frequency dynamics and have outperformed alternative methods for classification and parameter estimation tasks in various areas of population genetics. Thus, they are potentially well suited to the identification of adaptive introgression. Using simulations, we trained CNNs on genotype matrices derived from genomes sampled from the donor population, the recipient population and a related non-introgressed population, in order to distinguish regions of the genome evolving under adaptive introgression from those evolving neutrally or experiencing selective sweeps. Our CNN architecture exhibits 95% accuracy on simulated data, even when the genomes are unphased, and accuracy decreases only moderately in the presence of heterosis. As a proof of concept, we applied our trained CNNs to human genomic datasets—both phased and unphased—to detect candidates for adaptive introgression that shaped our evolutionary history.
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Affiliation(s)
- Graham Gower
- Lundbeck GeoGenetics Centre, Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pablo Iáñez Picazo
- Lundbeck GeoGenetics Centre, Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Matteo Fumagalli
- Department of Life Sciences, Silwood Park Campus, Imperial College London, London, United Kingdom
| | - Fernando Racimo
- Lundbeck GeoGenetics Centre, Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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19
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Fabritzek AG, Griebeler EM, Kadereit JW. Hybridization, ecogeographical displacement and the emergence of new lineages - A genotyping-by-sequencing and ecological niche and species distribution modelling study of Sempervivum tectorum L. (Houseleek). J Evol Biol 2021; 34:830-844. [PMID: 33714223 DOI: 10.1111/jeb.13784] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/18/2021] [Accepted: 03/03/2021] [Indexed: 11/28/2022]
Abstract
Ecogeographical displacement of homoploid hybrid lineages from their parents is well documented and considered an important mechanism to achieve reproductive isolation. In this study, we investigated the origin of the flowering plant species Sempervivum tectorum in the Massif Central (France) through homoploid hybridization between lineages of the species from the Rhine Gorge area (Germany) and the Pyrenees (France). We used genotyping-by-sequencing genetic data as evidence for the hybrid origin of the Massif Central lineage, and WorldClim climatic data and soil pH and soil temperature data collected by us for ecological niche and species distribution modelling. We could show that the Massif Central lineage shows hybrid admixture and that the niche of this lineage is significantly different from those of the parental lineages. In comparison with the parental niches, different variables of the niche of the hybrid lineage are intermediate, parental-combined or extreme. The different niche of the Massif Central populations thus can plausibly be interpreted as hybridization-derived. Our species distribution modelling for the Last Glacial Maximum and Mid-Holocene showed that the potential distribution of the hybrid lineage at the likely time of its origin in the Quaternary possibly was parapatric in relation to the largely sympatric distributions of the parental lineages. We hypothesize that reproductive isolation of the hybrid lineage from the parental lineages resulted from the segregation of distribution ranges by a differential response of the three lineages to a warming climate.
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Affiliation(s)
- Armin G Fabritzek
- Institut für Organismische und Molekulare Evolutionsbiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Eva Maria Griebeler
- Institut für Organismische und Molekulare Evolutionsbiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Joachim W Kadereit
- Institut für Organismische und Molekulare Evolutionsbiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
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20
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Liu Y, El-Kassaby YA. Transcriptome-wide analysis of introgression-resistant regions reveals genetic divergence genes under positive selection in Populus trichocarpa. Heredity (Edinb) 2021; 126:442-462. [PMID: 33214679 PMCID: PMC8027638 DOI: 10.1038/s41437-020-00388-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 11/09/2022] Open
Abstract
Comparing gene expression patterns and genetic polymorphisms between populations is of central importance for understanding the origin and maintenance of biodiversity. Based on population-specific gene expression levels and allele frequency differences, we sought to identify population divergence (PD) genes across the introgression-resistant genomic regions of Populus trichocarpa. Genes containing highly diverged loci [i.e., genetic divergence (GD)] or showing expression divergence (ED) between populations were widely distributed in the genome and substantially enriched in functional categories related to stress responses, disease resistance, timing of flowering, cell cycle regulation, plant growth, and development. Nine genomic regions showing evidence of strong positive selection were overlapped with GD genes, which had significant differences between Oregon (a southernmost peripheral deme) and the other demes. However, we did not find evidence that genes under positive selection show an enrichment for ED. PD genes and genes under selection pertained to the same gene classes, such as SERINE/CYSTEINE PROTEASE, ABC TRANSPORTER, GLYCOSYLTRANSFERASE and other transferases. Our analysis also revealed that GD genes were polymorphic within the species (41.9 ± 3.66 biallelic variants per gene), as previously reported in herbaceous plants. By contrast, ED genes contained less genetic variants (10.73 ± 1.14) and were likely highly expressed. In addition, we found that trans- rather than cis-acting variants considerably contribute to the evolution of >90% PD genes. Overall, this study elucidates that cohorts of PD genes agree with the general attributes of known speciation genes and GD genes will provide substrates for positive selection to operate on.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
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21
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Chen C, Yang W, Liu J, Xi Z, Zhang L, Hu Q. Population Transcriptomics Reveals Gene Flow and Introgression Between Two Non-sister Alpine Gentians. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.638230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Distributional shifts driven by Quaternary climatic oscillations have been suggested to cause interspecific hybridization and introgression. In this study, we aimed to test this hypothesis by using population transcriptomes and coalescent modeling of two alpine none-sister gentians. Previous studies suggested that historical hybridizations occurred between Gentiana siphonantha and G. straminea in the high-altitude Qinghai-Tibet Plateau although both species are not sister to each other with the most recent divergence. In the present study, we sequenced transcriptomes of 33 individuals from multiple populations of G. siphonantha and G. straminea. The two species are well delimited by nuclear genomic SNPs while phylogenetic analyses of plastomes clustered one G. straminea individual into the G. siphonantha group. Further population structure analyses of the nuclear SNPs suggested that two populations of G. siphonantha were admixed with around 15% ancestry from G. straminea. These analyses suggested genetic introgressions from G. straminea to G. siphonantha. In addition, our coalescent-based modeling results revealed that gene flow occurred between the two species since Last Glacier Maximum after their initial divergence, which might have leaded to the observed introgressions. Our results underscore the significance of transcriptome population data in determining timescale of interspecific gene flow and direction of the resulting introgression.
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22
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Menon M, Bagley JC, Page GFM, Whipple AV, Schoettle AW, Still CJ, Wehenkel C, Waring KM, Flores-Renteria L, Cushman SA, Eckert AJ. Adaptive evolution in a conifer hybrid zone is driven by a mosaic of recently introgressed and background genetic variants. Commun Biol 2021; 4:160. [PMID: 33547394 PMCID: PMC7864969 DOI: 10.1038/s42003-020-01632-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 11/18/2020] [Indexed: 01/30/2023] Open
Abstract
Extant conifer species may be susceptible to rapid environmental change owing to their long generation times, but could also be resilient due to high levels of standing genetic diversity. Hybridisation between closely related species can increase genetic diversity and generate novel allelic combinations capable of fuelling adaptive evolution. Our study unravelled the genetic architecture of adaptive evolution in a conifer hybrid zone formed between Pinus strobiformis and P. flexilis. Using a multifaceted approach emphasising the spatial and environmental patterns of linkage disequilibrium and ancestry enrichment, we identified recently introgressed and background genetic variants to be driving adaptive evolution along different environmental gradients. Specifically, recently introgressed variants from P. flexilis were favoured along freeze-related environmental gradients, while background variants were favoured along water availability-related gradients. We posit that such mosaics of allelic variants within conifer hybrid zones will confer upon them greater resilience to ongoing and future environmental change and can be a key resource for conservation efforts.
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Affiliation(s)
- Mitra Menon
- grid.27860.3b0000 0004 1936 9684Department of Evolution and Ecology, University of California, Davis, CA USA
| | - Justin C. Bagley
- grid.257992.20000 0001 0019 1845Department of Biology, Jacksonville State University, Jacksonville, AL USA
| | - Gerald F. M. Page
- grid.4391.f0000 0001 2112 1969Forest Ecosystems and Society, Oregon State University, Corvallis, OR USA
| | - Amy V. Whipple
- grid.261120.60000 0004 1936 8040Department of Biological Sciences and Merriam Powel Center for Environmental Research, Northern Arizona University, Flagstaff, AZ USA
| | - Anna W. Schoettle
- grid.497401.f0000 0001 2286 5230Rocky Mountain Research Station, USDA Forest Service, Fort Collins, CO USA
| | - Christopher J. Still
- grid.4391.f0000 0001 2112 1969Forest Ecosystems and Society, Oregon State University, Corvallis, OR USA
| | - Christian Wehenkel
- grid.412198.70000 0000 8724 8383Instituto de Silvicultura e Industria de la Madera, Universidad Juarez del Estado de Durango, Durango, Mexico
| | - Kristen M. Waring
- grid.261120.60000 0004 1936 8040School of Forestry, Northern Arizona University, Flagstaff, AZ USA
| | - Lluvia Flores-Renteria
- grid.263081.e0000 0001 0790 1491Department of Biology, San Diego State University, San Diego, CA USA
| | - Samuel A. Cushman
- grid.472551.00000 0004 0404 3120Rocky Mountain Research Station, USDA Forest Service, Flagstaff, AZ USA
| | - Andrew J. Eckert
- grid.224260.00000 0004 0458 8737Department of Biology, Virginia Commonwealth University, Richmond, VA USA
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23
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Nelson TC, Stathos AM, Vanderpool DD, Finseth FR, Yuan YW, Fishman L. Ancient and recent introgression shape the evolutionary history of pollinator adaptation and speciation in a model monkeyflower radiation (Mimulus section Erythranthe). PLoS Genet 2021; 17:e1009095. [PMID: 33617525 PMCID: PMC7951852 DOI: 10.1371/journal.pgen.1009095] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/11/2021] [Accepted: 01/22/2021] [Indexed: 12/20/2022] Open
Abstract
Inferences about past processes of adaptation and speciation require a gene-scale and genome-wide understanding of the evolutionary history of diverging taxa. In this study, we use genome-wide capture of nuclear gene sequences, plus skimming of organellar sequences, to investigate the phylogenomics of monkeyflowers in Mimulus section Erythranthe (27 accessions from seven species). Taxa within Erythranthe, particularly the parapatric and putatively sister species M. lewisii (bee-pollinated) and M. cardinalis (hummingbird-pollinated), have been a model system for investigating the ecological genetics of speciation and adaptation for over five decades. Across >8000 nuclear loci, multiple methods resolve a predominant species tree in which M. cardinalis groups with other hummingbird-pollinated taxa (37% of gene trees), rather than being sister to M. lewisii (32% of gene trees). We independently corroborate a single evolution of hummingbird pollination syndrome in Erythranthe by demonstrating functional redundancy in genetic complementation tests of floral traits in hybrids; together, these analyses overturn a textbook case of pollination-syndrome convergence. Strong asymmetries in allele sharing (Patterson's D-statistic and related tests) indicate that gene tree discordance reflects ancient and recent introgression rather than incomplete lineage sorting. Consistent with abundant introgression blurring the history of divergence, low-recombination and adaptation-associated regions support the new species tree, while high-recombination regions generate phylogenetic evidence for sister status for M. lewisii and M. cardinalis. Population-level sampling of core taxa also revealed two instances of chloroplast capture, with Sierran M. lewisii and Southern Californian M. parishii each carrying organelle genomes nested within respective sympatric M. cardinalis clades. A recent organellar transfer from M. cardinalis, an outcrosser where selfish cytonuclear dynamics are more likely, may account for the unexpected cytoplasmic male sterility effects of selfer M. parishii organelles in hybrids with M. lewisii. Overall, our phylogenomic results reveal extensive reticulation throughout the evolutionary history of a classic monkeyflower radiation, suggesting that natural selection (re-)assembles and maintains species-diagnostic traits and barriers in the face of gene flow. Our findings further underline the challenges, even in reproductively isolated species, in distinguishing re-use of adaptive alleles from true convergence and emphasize the value of a phylogenomic framework for reconstructing the evolutionary genetics of adaptation and speciation.
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Affiliation(s)
- Thomas C. Nelson
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Angela M. Stathos
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Daniel D. Vanderpool
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Findley R. Finseth
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Yao-wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
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24
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Nieto Feliner G, Casacuberta J, Wendel JF. Genomics of Evolutionary Novelty in Hybrids and Polyploids. Front Genet 2020; 11:792. [PMID: 32849797 PMCID: PMC7399645 DOI: 10.3389/fgene.2020.00792] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/03/2020] [Indexed: 12/15/2022] Open
Abstract
It has long been recognized that hybridization and polyploidy are prominent processes in plant evolution. Although classically recognized as significant in speciation and adaptation, recognition of the importance of interspecific gene flow has dramatically increased during the genomics era, concomitant with an unending flood of empirical examples, with or without genome doubling. Interspecific gene flow is thus increasingly thought to lead to evolutionary innovation and diversification, via adaptive introgression, homoploid hybrid speciation and allopolyploid speciation. Less well understood, however, are the suite of genetic and genomic mechanisms set in motion by the merger of differentiated genomes, and the temporal scale over which recombinational complexity mediated by gene flow might be expressed and exposed to natural selection. We focus on these issues here, considering the types of molecular genetic and genomic processes that might be set in motion by the saltational event of genome merger between two diverged species, either with or without genome doubling, and how these various processes can contribute to novel phenotypes. Genetic mechanisms include the infusion of new alleles and the genesis of novel structural variation including translocations and inversions, homoeologous exchanges, transposable element mobilization and novel insertional effects, presence-absence variation and copy number variation. Polyploidy generates massive transcriptomic and regulatory alteration, presumably set in motion by disrupted stoichiometries of regulatory factors, small RNAs and other genome interactions that cascade from single-gene expression change up through entire networks of transformed regulatory modules. We highlight both these novel combinatorial possibilities and the range of temporal scales over which such complexity might be generated, and thus exposed to natural selection and drift.
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Affiliation(s)
- Gonzalo Nieto Feliner
- Department of Biodiversity and Conservation, Real Jardín Botánico, CSIC, Madrid, Spain
| | - Josep Casacuberta
- Center for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB), Barcelona, Spain
| | - Jonathan F. Wendel
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, United States
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25
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Shang H, Hess J, Pickup M, Field DL, Ingvarsson PK, Liu J, Lexer C. Evolution of strong reproductive isolation in plants: broad-scale patterns and lessons from a perennial model group. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190544. [PMID: 32654641 DOI: 10.1098/rstb.2019.0544] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many recent studies have addressed the mechanisms operating during the early stages of speciation, but surprisingly few studies have tested theoretical predictions on the evolution of strong reproductive isolation (RI). To help address this gap, we first undertook a quantitative review of the hybrid zone literature for flowering plants in relation to reproductive barriers. Then, using Populus as an exemplary model group, we analysed genome-wide variation for phylogenetic tree topologies in both early- and late-stage speciation taxa to determine how these patterns may be related to the genomic architecture of RI. Our plant literature survey revealed variation in barrier complexity and an association between barrier number and introgressive gene flow. Focusing on Populus, our genome-wide analysis of tree topologies in speciating poplar taxa points to unusually complex genomic architectures of RI, consistent with earlier genome-wide association studies. These architectures appear to facilitate the 'escape' of introgressed genome segments from polygenic barriers even with strong RI, thus affecting their relationships with recombination rates. Placed within the context of the broader literature, our data illustrate how phylogenomic approaches hold great promise for addressing the evolution and temporary breakdown of RI during late stages of speciation. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- Huiying Shang
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.,Vienna Graduate School of Population Genetics, Vienna, Austria
| | - Jaqueline Hess
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.,Helmholtz Centre for Environmental Research, Halle (Saale), Germany
| | - Melinda Pickup
- Institute of Science and Technology (IST), Klosterneuburg, Austria
| | - David L Field
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.,Edith Cowan University, Perth, Australia
| | - Pär K Ingvarsson
- Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Jianquan Liu
- Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, People's Republic of China
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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26
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Chen Z, Ai F, Zhang J, Ma X, Yang W, Wang W, Su Y, Wang M, Yang Y, Mao K, Wang Q, Lascoux M, Liu J, Ma T. Survival in the Tropics despite isolation, inbreeding and asexual reproduction: insights from the genome of the world's southernmost poplar (Populus ilicifolia). THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:430-442. [PMID: 32168389 DOI: 10.1111/tpj.14744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 02/04/2020] [Accepted: 03/02/2020] [Indexed: 05/16/2023]
Abstract
Species are becoming extinct at unprecedented rates as a consequence of human activity. Hence it is important to understand the evolutionary dynamics of species with already small population sizes. Populus ilicifolia is a vulnerable poplar species that is isolated from other poplar species and is uniquely adapted to the Tropics. It has a very limited size, reproduces partly clonally and is therefore an excellent case study for conservation genomics. We present here the first annotated draft genome of P. ilicifolia, characterize genome-wide patterns of polymorphisms and compare those to other poplar species with larger natural ranges. P. ilicifolia experienced a more prolonged and severe decline of effective population size (Ne ) and signs of genetic erosion than any other poplar species with which it was compared. At present, the species has the lowest genome-wide genetic diversity, the highest abundance of long runs of homozygosity, high inbreeding levels as well as a high overall accumulation of deleterious variants. However, more effective purging of severely deleterious variants and adaptation to the Tropics may have contributed to its survival. Hence, in spite of its limited genetic variation, it is certainly worth pursuing the conservation efforts of this unique species.
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Affiliation(s)
- Zeyuan Chen
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Fandi Ai
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Junlin Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Xinzhi Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Wenlu Yang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Weiwei Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Yutao Su
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Mingcheng Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Yongzhi Yang
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Kangshan Mao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
| | - Qingfeng Wang
- Key Laboratory of Aquatic Botany and Watershed Ecology, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Martin Lascoux
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen, 18D 75326, Uppsala, Sweden
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Tao Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China
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27
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Cronk Q, Soolanayakanahally R, Bräutigam K. Gene expression trajectories during male and female reproductive development in balsam poplar (Populus balsamifera L.). Sci Rep 2020; 10:8413. [PMID: 32439903 PMCID: PMC7242425 DOI: 10.1038/s41598-020-64938-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 04/24/2020] [Indexed: 12/19/2022] Open
Abstract
Plant reproductive development from the first appearance of reproductively committed axes through to floral maturation requires massive and rapid remarshalling of gene expression. In dioecious species such as poplar this is further complicated by divergent male and female developmental programs. We used seven time points in male and female balsam poplar (Populus balsamifera L.) buds and catkins representing the full annual flowering cycle, to elucidate the effects of time and sex on gene expression during reproductive development. Time (developmental stage) is dominant in patterning gene expression with the effect of sex nested within this. Here, we find (1) evidence for five successive waves of alterations to the chromatin landscape which may be important in setting the overall reproductive trajectory, regardless of sex. (2) Each individual developmental stage is further characterized by marked sex-differential gene expression. (3) Consistent sexually differentiated gene expression regardless of developmental stage reveal candidates for high-level regulators of sex and include the female-specific poplar ARR17 homologue. There is also consistent male-biased expression of the MADS-box genes PISTILLATA and APETALA3. Our work provides insights into expression trajectories shaping reproductive development, its potential underlying mechanisms, and sex-specific translation of the genome information into reproductive structures in balsam poplar.
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Affiliation(s)
- Quentin Cronk
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Raju Soolanayakanahally
- Indian Head Research Farm, Agriculture and Agri-Food Canada, Indian Head, SK, S0G 2K0, Canada
| | - Katharina Bräutigam
- Department of Biology, University of Toronto, Mississauga, ON, L5L 1C6, Canada.
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28
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Nagamitsu T, Uchiyama K, Izuno A, Shimizu H, Nakanishi A. Environment-dependent introgression from Quercus dentata to a coastal ecotype of Quercus mongolica var. crispula in northern Japan. THE NEW PHYTOLOGIST 2020; 226:1018-1028. [PMID: 31424559 PMCID: PMC7216917 DOI: 10.1111/nph.16131] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 08/09/2019] [Indexed: 05/25/2023]
Abstract
Introgression from one species in a specific environment to another may facilitate colonization of the environment by the recipient species. However, such environment-dependent introgression has been clarified in limited plant taxa. In northern Japan, there are two interfertile oak species: Quercus dentata (Qd) in coastal areas and Q. mongolica var. crispula (Qc) in inland areas. However, at higher latitudes where Qd is rare, a coastal Qc ecotype with Qd-like traits is distributed in the coastal areas. We distinguished inland Qc, coastal Qc, and coastal Qd populations based on genome-wide genotypes and multitrait phenotypes and verified introgression from coastal Qd to coastal Qc using reduced library sequencing. Genotypes and phenotypes differed among the populations, and coastal Qc was intermediate between inland Qc and coastal Qd. The ABBA-BABA test showed introgression from coastal Qd to coastal Qc. In coastal Qc, we found various stages of introgression after the first generation of backcross but detected no genomic regions where introgression was enhanced. Overall, we show evidence for introgression from a coastal species to an ecotype of an inland species, which has colonized the coastal environment. It remains unclear whether introgressed alleles are selected in the coastal environment.
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Affiliation(s)
- Teruyoshi Nagamitsu
- Hokkaido Research Center, Forestry and Forest Products Research InstituteForest Research and Management OrganizationSapporo062‐8516Japan
| | - Kentaro Uchiyama
- Department of Forest Molecular Genetics and BiotechnologyForestry and Forest Products Research InstituteForest Research and Management OrganizationTsukuba305‐8687Japan
| | - Ayako Izuno
- Department of Forest Molecular Genetics and BiotechnologyForestry and Forest Products Research InstituteForest Research and Management OrganizationTsukuba305‐8687Japan
| | - Hajime Shimizu
- Greenery Research and Information CenterForestry Research InstituteHokkaido Research OrganizationBibai079‐0198Japan
| | - Atsushi Nakanishi
- Hokkaido Research Center, Forestry and Forest Products Research InstituteForest Research and Management OrganizationSapporo062‐8516Japan
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29
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Abstract
Introgressive hybridization results in the transfer of genetic material between species, often with fitness implications for the recipient species. The development of statistical methods for detecting the signatures of historical introgression in whole-genome data has been a major area of focus. Although existing techniques are able to identify the taxa that exchanged genes during introgression using a four-taxon system, most methods do not explicitly distinguish which taxon served as donor and which as recipient during introgression (i.e., polarization of introgression directionality). Existing methods that do polarize introgression are often only able to do so when there is a fifth taxon available and that taxon is sister to one of the taxa involved in introgression. Here, we present divergence-based introgression polarization (DIP), a method for polarizing introgression using patterns of sequence divergence across whole genomes, which operates in a four-taxon context. Thus, DIP can be applied to infer the directionality of introgression when additional taxa are not available. We use simulations to show that DIP can polarize introgression and identify potential sources of bias in the assignment of directionality, and we apply DIP to a well-described hominin introgression event.
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Affiliation(s)
- Evan S Forsythe
- Department of Biology, Colorado State University
- School of Plant Sciences, University of Arizona
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30
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Wang M, Zhang L, Zhang Z, Li M, Wang D, Zhang X, Xi Z, Keefover-Ring K, Smart LB, DiFazio SP, Olson MS, Yin T, Liu J, Ma T. Phylogenomics of the genus Populus reveals extensive interspecific gene flow and balancing selection. THE NEW PHYTOLOGIST 2020; 225:1370-1382. [PMID: 31550399 DOI: 10.1111/nph.16215] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 09/16/2019] [Indexed: 05/10/2023]
Abstract
Phylogenetic analysis is complicated by interspecific gene flow and the presence of shared ancestral polymorphisms, particularly those maintained by balancing selection. In this study, we aimed to examine the prevalence of these factors during the diversification of Populus, a model tree genus in the Northern Hemisphere. We constructed phylogenetic trees of 29 Populus taxa using 80 individuals based on re-sequenced genomes. Our species tree analyses recovered four main clades in the genus based on consensus nuclear phylogenies, but in conflict with the plastome phylogeny. A few interspecific relationships remained unresolved within the multiple-species clade because of inconsistent gene trees. Our results indicated that gene flow has been widespread within each clade and also occurred among the four clades during their early divergence. We identified 45 candidate genes with ancient polymorphisms maintained by balancing selection. These genes were mainly associated with mating compatibility, growth and stress resistance. Both gene flow and selection-mediated ancient polymorphisms are prevalent in the genus Populus. These are potentially important contributors to adaptive variation. Our results provide a framework for the diversification of model tree genus that will facilitate future comparative studies.
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Affiliation(s)
- Mingcheng Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Lei Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Zhiyang Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Mengmeng Li
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Deyan Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Xu Zhang
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Zhenxiang Xi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Ken Keefover-Ring
- Departments of Botany and Geography, University of Wisconsin-Madison, 430 Lincoln Dr., Madison, WI, 53706, USA
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Science, New York State Agricultural Experiment Station, Cornell University, Geneva, NY, 14456, USA
| | - Stephen P DiFazio
- Department of Biology, West Virginia University, Morgantown, WV, 25606, USA
| | - Matthew S Olson
- Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX, 79409-3131, USA
| | - Tongming Yin
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing, 210037, China
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
- State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology & College of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Tao Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
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31
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Godbout J, Gros-Louis M, Lamothe M, Isabel N. Going with the flow: Intraspecific variation may act as a natural ally to counterbalance the impacts of global change for the riparian species Populus deltoides. Evol Appl 2020; 13:176-194. [PMID: 31892951 PMCID: PMC6935597 DOI: 10.1111/eva.12854] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/16/2019] [Accepted: 07/31/2019] [Indexed: 12/19/2022] Open
Abstract
The speed and magnitude of global change will have major impacts on riparian ecosystems, thereby leading to greater forest vulnerability. Assessing species' adaptive capacities to provide relevant information for vulnerability assessments remains challenging, especially for nonmodel species like the North American Populus deltoides W. Bartram ex Marshall. The objective of this study was to understand how genomic diversity of this foundation species was shaped by its environment (climate, soil, and biotic interactions) to gauge its adaptive capacity. We used two complementary approaches to get a full portrait of P. deltoides genetic diversity at both the species and whole-genome ranges. First, we used a set of 93 nuclear and three chloroplastic SNP markers in 946 individuals covering most of the species' natural distribution. Then, to measure the degree of intraspecific divergence at the whole-genome level and to support the outlier and genomic-environment association analyses, we used a sequence capture approach on DNA pools. Three distinct lineages for P. deltoides were detected, and their current distribution was associated with abiotic and biotic variations. The comparison between both cpDNA and ncDNA patterns showed that gene flow between the lineages is unbalanced. The southern and northeastern populations may benefit from the input, through river flow, of novel alleles located upstream to their local gene pools. These alleles could migrate from populations that are already adapted to conditions that fit the predicted climates in the receiving local populations, hotter at the northeastern limit and drier in the Central United States. These "preadapted" incoming alleles may help to cope with maladaptation in populations facing changing conditions.
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Affiliation(s)
- Julie Godbout
- Ministère des Forêts, de la Faune et des Parcs, Direction de la recherche forestièreQuébecQCCanada
- Canadian Forest Service, Laurentian Forestry CentreNatural Resources CanadaQuébecQCCanada
| | | | - Manuel Lamothe
- Canadian Forest Service, Laurentian Forestry CentreNatural Resources CanadaQuébecQCCanada
| | - Nathalie Isabel
- Canadian Forest Service, Laurentian Forestry CentreNatural Resources CanadaQuébecQCCanada
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32
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Nieto Feliner G, Rosato M, Alegre G, San Segundo P, Rosselló JA, Garnatje T, Garcia S. Dissimilar molecular and morphological patterns in an introgressed peripheral population of a sand dune species (Armeria pungens, Plumbaginaceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:1072-1082. [PMID: 31349366 DOI: 10.1111/plb.13035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 07/23/2019] [Indexed: 05/26/2023]
Abstract
Introgression is a poorly understood evolutionary outcome of hybridisation because it may remain largely undetected whenever it involves the transfer of small parts of the genome from one species to another. Aiming to understand the early stages of this process, a putative case from the southernmost border of the Armeria pungens range from its congener A. macrophylla is revisited following the discovery of a subpopulation that does not show phenotypic signs of introgression and resembles typical A. pungens. We analysed morphometrics, nuclear ribosomal DNA ITS and plastid DNA (trnL-trnF) sequences, genome size, 45S and 5S rDNA loci-FISH data and nrDNA IGS sequences. Within the study site, most individuals match morphologies of either of the two hybridising species, particularly the new subpopulation, with intermediate phenotypes being scarce. This pattern does not fully fit molecular evidence revealing two ITS ribotypes co-occurring intragenomically in most plants from the study site and one single plastid haplotype. Genome size and structural features of the IGS sequences both indicate that A. pungens from the study site is genetically more similar to its sympatric congener than to the remainder of its conspecifics. Introgression of A. macrophylla into A. pungens and plastid capture explain all the evidence analysed. However, important features to understand the origin and fate of the introgressed population, such as the degree and direction of introgression, which are important for understanding early stages of hybridisation in plants with low reproductive barriers, should be addressed with new data.
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Affiliation(s)
| | - M Rosato
- Jardín Botánico, ICBIBE-Unidad Asociada CSIC, Universidad de Valencia, Valencia, Spain
| | - G Alegre
- Institut Botànic de Barcelona (IBB-CSIC-ICUB), Barcelona, Catalonia, Spain
| | | | - J A Rosselló
- Jardín Botánico, ICBIBE-Unidad Asociada CSIC, Universidad de Valencia, Valencia, Spain
| | - T Garnatje
- Institut Botànic de Barcelona (IBB-CSIC-ICUB), Barcelona, Catalonia, Spain
| | - S Garcia
- Institut Botànic de Barcelona (IBB-CSIC-ICUB), Barcelona, Catalonia, Spain
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McKown AD, Klápště J, Guy RD, Corea ORA, Fritsche S, Ehlting J, El-Kassaby YA, Mansfield SD. A role for SPEECHLESS in the integration of leaf stomatal patterning with the growth vs disease trade-off in poplar. THE NEW PHYTOLOGIST 2019; 223:1888-1903. [PMID: 31081152 DOI: 10.1111/nph.15911] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 04/29/2019] [Indexed: 05/08/2023]
Abstract
Occurrence of stomata on both leaf surfaces (amphistomaty) promotes higher stomatal conductance and photosynthesis while simultaneously increasing exposure to potential disease agents in black cottonwood (Populus trichocarpa). A genome-wide association study (GWAS) with 2.2M single nucleotide polymorphisms generated through whole-genome sequencing found 280 loci associated with variation in adaxial stomatal traits, implicating genes regulating stomatal development and behavior. Strikingly, numerous loci regulating plant growth and response to biotic and abiotic stresses were also identified. The most significant locus was a poplar homologue of SPEECHLESS (PtSPCH1). Individuals possessing PtSPCH1 alleles associated with greater adaxial stomatal density originated primarily from environments with shorter growing seasons (e.g. northern latitudes, high elevations) or with less precipitation. PtSPCH1 was expressed in developing leaves but not developing stem xylem. In developing leaves, RNA sequencing showed patterns of coordinated expression between PtSPCH1 and other GWAS-identified genes. The breadth of our GWAS results suggests that the evolution of amphistomaty is part of a larger, complex response in plants. Suites of genes underpin this response, retrieved through genetic association to adaxial stomata, and show coordinated expression during development. We propose that the occurrence of amphistomaty in P. trichocarpa involves PtSPCH1 and reflects selection for supporting rapid growth over investment in immunity.
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Affiliation(s)
- Athena D McKown
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jaroslav Klápště
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Genetics and Physiology of Forest Trees, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, 165 21, Czech Republic
- Scion (New Zealand Forest Research Institute Ltd), Whakarewarewa, Rotorua, 3046, New Zealand
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Oliver R A Corea
- Department of Biology and Centre for Forest Biology, University of Victoria, Victoria, BC, V8W 3N5, Canada
| | - Steffi Fritsche
- Scion (New Zealand Forest Research Institute Ltd), Whakarewarewa, Rotorua, 3046, New Zealand
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jürgen Ehlting
- Department of Biology and Centre for Forest Biology, University of Victoria, Victoria, BC, V8W 3N5, Canada
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Shawn D Mansfield
- Department of Wood Science, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Ma Y, Wang J, Hu Q, Li J, Sun Y, Zhang L, Abbott RJ, Liu J, Mao K. Ancient introgression drives adaptation to cooler and drier mountain habitats in a cypress species complex. Commun Biol 2019; 2:213. [PMID: 31240251 PMCID: PMC6581913 DOI: 10.1038/s42003-019-0445-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 04/29/2019] [Indexed: 11/11/2022] Open
Abstract
Introgression may act as an important source of new genetic variation to facilitate the adaptation of organisms to new environments, yet how introgression might enable tree species to adapt to higher latitudes and elevations remains unclear. Applying whole-transcriptome sequencing and population genetic analyses, we present an example of ancient introgression from a cypress species (Cupressus gigantea) that occurs at higher latitude and elevation on the Qinghai-Tibet Plateau into a related species (C. duclouxiana), which has likely aided the latter species to extend its range by colonizing cooler and drier mountain habitats during postglacial periods. We show that 16 introgressed candidate adaptive loci could have played pivotal roles in response to diverse stresses experienced in a high-elevation environment. Our findings provide new insights into the evolutionary history of Qinghai-Tibet Plateau plants and the importance of introgression in the adaptation of species to climate change.
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Affiliation(s)
- Yazhen Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Ji Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Quanjun Hu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Jialiang Li
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Yongshuai Sun
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 666303 Mengla, P. R. China
| | - Lei Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Richard J. Abbott
- School of Biology, Mitchell Building, University of St Andrews, St Andrews, Fife, KY16 9TH UK
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
| | - Kangshan Mao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, 610065 Chengdu, Sichuan P. R. China
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Burge DO, Parker VT, Mulligan M, Sork VL. Influence of a climatic gradient on genetic exchange between two oak species. AMERICAN JOURNAL OF BOTANY 2019; 106:864-878. [PMID: 31216071 DOI: 10.1002/ajb2.1315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
PREMISE In plant groups with limited intrinsic barriers to gene flow, it is thought that environmental conditions can modulate interspecific genetic exchange. Oaks are known for limited barriers to gene flow among closely related species. Here, we use Quercus as a living laboratory in which to pursue a fundamental question in plant evolution: Do environmental gradients restrict or promote genetic exchange between species? METHODS We focused on two North American oaks, the rare Quercus dumosa and the widespread Q. berberidifolia. We sampled intensively along a contact zone in California, USA. We sequenced restriction site-associated DNA markers and measured vegetative phenotype. We tested for genetic exchange, the association with climate, and the effect on phenotype. RESULTS There is evidence for genetic exchange between the species. Admixed plants are found in areas of intermediate climate, while less admixed plants are found at the extremes of the climatic gradient. Genetic and phenotypic patterns are out of phase in the contact zone; some plants display the phenotype of one species but are genetically associated with another. CONCLUSIONS Our results support the hypothesis that a strong climatic gradient can promote genetic exchange between species. The overall weak correlation between genotype and phenotype in the contact zone between the species suggests that genetic exchange can lead to the breakdown of trait combinations used to define species. This incongruency predicts ongoing problems for conservation of Q. dumosa, with implications for conservation of other oaks.
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Affiliation(s)
- Dylan O Burge
- Department of Ecology and Evolutionary Biology, University of California, Box 957239, Los Angeles, California, 90095-7239, USA
- 554 Vallombrosa Avenue, P.O. Box 418, Chico, California, 95927, USA
| | - V Thomas Parker
- San Francisco State University, 1600 Holloway Avenue, San Francisco, California, 94132, USA
| | - Margaret Mulligan
- San Diego Natural History Museum, Balboa Park, 1788 El Prado, San Diego, California, 92101, USA
| | - Victoria L Sork
- Department of Ecology and Evolutionary Biology, University of California, Box 957239, Los Angeles, California, 90095-7239, USA
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Abstract
Introgression is emerging as an important source of novel genetic variation, alongside standing variation and mutation. It is adaptive when such introgressed alleles are maintained by natural selection. Recently, there has been an explosion in the number of studies on adaptive introgression. In this review, we take a plant perspective centred on four lines of evidence: (i) introgression, (ii) selection, (iii) phenotype and (iv) fitness. While advances in genomics have contributed to our understanding of introgression and porous species boundaries (task 1), and the detection of signatures of selection in introgression (task 2), the investigation of adaptive introgression critically requires links to phenotypic variation and fitness (tasks 3 and 4). We also discuss the conservation implications of adaptive introgression in the face of climate change. Adaptive introgression is particularly important in rapidly changing environments, when standing genetic variation and mutation alone may only offer limited potential for adaptation. We conclude that clarifying the magnitude and fitness effects of introgression with improved statistical techniques, coupled with phenotypic evidence, has great potential for conservation and management efforts.
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Affiliation(s)
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Quentin C B Cronk
- Department of Botany, University of British Columbia, Vancouver, Canada
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McFarlane SE, Pemberton JM. Detecting the True Extent of Introgression during Anthropogenic Hybridization. Trends Ecol Evol 2019; 34:315-326. [DOI: 10.1016/j.tree.2018.12.013] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 12/10/2018] [Accepted: 12/18/2018] [Indexed: 10/27/2022]
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Melnikova NV, Kudryavtseva AV, Borkhert EV, Pushkova EN, Fedorova MS, Snezhkina AV, Krasnov GS, Dmitriev AA. Sex-specific polymorphism of MET1 and ARR17 genes in Populus × sibirica. Biochimie 2019; 162:26-32. [PMID: 30935960 DOI: 10.1016/j.biochi.2019.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 03/27/2019] [Indexed: 01/25/2023]
Abstract
The genus Populus is an effective model in tree genetics. This genus includes dioecious species and, recently, whole genome resequencing of P. trichocarpa and P. balsamifera enabled the identification of sex-linked regions and sex-associated single nucleotide polymorphisms (SNPs). These results created new opportunities to study sex determination in poplars. In the present work, we performed deep sequencing of genes encoding METHYLTRANSFERASE1 (MET1) and homolog of ARABIDOPSIS RESPONSE REGULATOR 17 (ARR17), which are localized in a sex-linked region of Populus genome and contain a number of sex-associated SNPs. Amplicon libraries for 38 samples of P. × sibirica (19 males and 19 females) were sequenced on MiSeq Illumina (300 nt paired-end reads) and approximately 4000× coverage was obtained for each sample. In total, from 80 to 179 SNPs were detected in poplar individuals for MET1, and from 16 to 49 SNPs were detected for ARR17. We identified 17 sex-specific SNPs (11 in MET1 and 6 in ARR17) - they were present in all males but absent in all females. For identified sex-specific SNP sites, females were homozygous, while males were heterozygous. Moreover, colocation of sex-specific SNPs confirming the XY sex-determination system of poplars was revealed: in one allelic variant, males had the same nucleotides as females, while in the other, sex-specific SNPs were present. Based on the data obtained, we developed and successfully applied a high-resolution melting-based approach for sex identification in poplars. The developed molecular markers are useful for distinguishing between male and female poplars in scientific research and can also be applied to select male-only genotypes for use in city landscaping and production of paper, pulp, and biofuel.
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Affiliation(s)
- Nataliya V Melnikova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Anna V Kudryavtseva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Elena V Borkhert
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Elena N Pushkova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Maria S Fedorova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Anastasiya V Snezhkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - George S Krasnov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
| | - Alexey A Dmitriev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova 32, Moscow, 119991, Russia.
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Taylor SA, Larson EL. Insights from genomes into the evolutionary importance and prevalence of hybridization in nature. Nat Ecol Evol 2019; 3:170-177. [DOI: 10.1038/s41559-018-0777-y] [Citation(s) in RCA: 211] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 12/04/2018] [Indexed: 01/27/2023]
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Hamilton JA, Miller JM. From transects to transcripts: Teasing apart the architecture of reproductive isolation. Mol Ecol 2019; 27:1339-1341. [PMID: 29663588 DOI: 10.1111/mec.14516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 01/19/2018] [Indexed: 11/29/2022]
Abstract
Understanding the processes underlying speciation has long been a challenge to evolutionary biologists. This spurs from difficulties teasing apart the various mechanisms that contribute to the evolution of barriers to reproduction. The study by Rafati et al. () in this issue of Molecular Ecology combines spatially explicit whole-genome resequencing with evaluation of differential gene expression across individuals with mixed ancestry to associate the genomic architecture of reproductive barriers with expression of reproductive incompatibilities. In a natural hybrid zone between rabbit subspecies, Oryctolagus cuniculus cuniculus and O. c. algirus (Figure ), Rafati et al. () use landscape-level patterns of allele frequency variation to identify potential candidate regions of the genome associated with reproductive isolation. These candidate regions are used to test predictions associated with the genomic architecture of reproductive barriers, including the role of structural rearrangements, enrichment of functional categories associated with incompatibilities, and the contribution of protein-coding versus regulatory changes. A lack of structural rearrangements and limited protein-coding changes in candidate regions point towards the importance of regulatory variation as major contributors to genetic incompatibilities, while functional enrichments indicate overrepresentation of genes associated with male infertility. To quantify phenotypic expression of proposed incompatibilities, the authors assess gene expression of experimental crosses. Extensive misregulation of gene expression within the testes of backcross hybrids relative to F1 and parental individuals provides an important link between genotype and phenotype, validating hypotheses developed from assessment of genomic architectures. Together, this work shows how pairing natural hybrid zones with experimental crosses can be used to link observations in nature to mechanistic underpinnings that may be tested experimentally.
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Affiliation(s)
- Jill A Hamilton
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | - Joshua M Miller
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
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41
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Burgarella C, Barnaud A, Kane NA, Jankowski F, Scarcelli N, Billot C, Vigouroux Y, Berthouly-Salazar C. Adaptive Introgression: An Untapped Evolutionary Mechanism for Crop Adaptation. FRONTIERS IN PLANT SCIENCE 2019; 10:4. [PMID: 30774638 PMCID: PMC6367218 DOI: 10.3389/fpls.2019.00004] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 01/04/2019] [Indexed: 05/18/2023]
Abstract
Global environmental changes strongly impact wild and domesticated species biology and their associated ecosystem services. For crops, global warming has led to significant changes in terms of phenology and/or yield. To respond to the agricultural challenges of this century, there is a strong need for harnessing the genetic variability of crops and adapting them to new conditions. Gene flow, from either the same species or a different species, may be an immediate primary source to widen genetic diversity and adaptions to various environments. When the incorporation of a foreign variant leads to an increase of the fitness of the recipient pool, it is referred to as "adaptive introgression". Crop species are excellent case studies of this phenomenon since their genetic variability has been considerably reduced over space and time but most of them continue exchanging genetic material with their wild relatives. In this paper, we review studies of adaptive introgression, presenting methodological approaches and challenges to detecting it. We pay particular attention to the potential of this evolutionary mechanism for the adaptation of crops. Furthermore, we discuss the importance of farmers' knowledge and practices in shaping wild-to-crop gene flow. Finally, we argue that screening the wild introgression already existing in the cultivated gene pool may be an effective strategy for uncovering wild diversity relevant for crop adaptation to current environmental changes and for informing new breeding directions.
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Affiliation(s)
- Concetta Burgarella
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR AGAP, Montpellier, France
- AGAP, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut National de la Recherche Agronomique, Montpellier SupAgro, Montpellier, France
- *Correspondence: Concetta Burgarella, Cécile Berthouly-Salazar,
| | - Adeline Barnaud
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Ndjido Ardo Kane
- Laboratoire National de Recherches sur les Productions Végétales, Institut Sénégalais de Recherches Agricoles, Dakar, Senegal
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Dakar, Senegal
| | - Frédérique Jankowski
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UPR GREEN, Montpellier, France
- GREEN, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Université de Montpellier, Montpellier, France
- Bureau d’Analyses Macro-Economiques, Institut Sénégalais de Recherches Agricoles, Dakar, Senegal
| | - Nora Scarcelli
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Claire Billot
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR AGAP, Montpellier, France
- AGAP, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut National de la Recherche Agronomique, Montpellier SupAgro, Montpellier, France
| | - Yves Vigouroux
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Cécile Berthouly-Salazar
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Dakar, Senegal
- *Correspondence: Concetta Burgarella, Cécile Berthouly-Salazar,
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Franchini P, Jones JC, Xiong P, Kneitz S, Gompert Z, Warren WC, Walter RB, Meyer A, Schartl M. Long-term experimental hybridisation results in the evolution of a new sex chromosome in swordtail fish. Nat Commun 2018; 9:5136. [PMID: 30510159 PMCID: PMC6277394 DOI: 10.1038/s41467-018-07648-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 11/13/2018] [Indexed: 01/13/2023] Open
Abstract
The remarkable diversity of sex determination mechanisms known in fish may be fuelled by exceptionally high rates of sex chromosome turnovers or transitions. However, the evolutionary causes and genomic mechanisms underlying this variation and instability are yet to be understood. Here we report on an over 30-year evolutionary experiment in which we tested the genomic consequences of hybridisation and selection between two Xiphophorus fish species with different sex chromosome systems. We find that introgression and imposing selection for pigmentation phenotypes results in the retention of an unexpectedly large maternally derived genomic region. During the hybridisation process, the sex-determining region of the X chromosome from one parental species was translocated to an autosome in the hybrids leading to the evolution of a new sex chromosome. Our results highlight the complexity of factors contributing to patterns observed in hybrid genomes, and we experimentally demonstrate that hybridisation can catalyze rapid evolution of a new sex chromosome. Fish have a high diversity of sex-determining systems, but the mechanisms responsible for this are not well understood. Here, Franchini et al. show how hybridization and backcrossing have led to the evolution of a new sex chromosome in swordtail fish during 30 years of experimental evolution.
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Affiliation(s)
- Paolo Franchini
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Julia C Jones
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.,Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, 75123, Sweden
| | - Peiwen Xiong
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Susanne Kneitz
- Physiological Chemistry, Biozentrum, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | | | - Wesley C Warren
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, 63108, MO, USA
| | - Ronald B Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, 78666-4616, TX, USA
| | - Axel Meyer
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany. .,Radcliffe Institute for Advanced Study, Harvard University, 9 Garden Street, Cambridge, MA, 02139, USA.
| | - Manfred Schartl
- Physiological Chemistry, Biozentrum, University of Würzburg, Am Hubland, 97074, Würzburg, Germany. .,Comprehensive Cancer Centre, University Clinic Würzburg, Josef Schneider Straße 6, 97074, Würzburg, Germany. .,Hagler Institute for Advanced Study and Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
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43
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Ru D, Sun Y, Wang D, Chen Y, Wang T, Hu Q, Abbott RJ, Liu J. Population genomic analysis reveals that homoploid hybrid speciation can be a lengthy process. Mol Ecol 2018; 27:4875-4887. [PMID: 30357974 DOI: 10.1111/mec.14909] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/22/2018] [Accepted: 10/02/2018] [Indexed: 12/26/2022]
Abstract
An increasing number of species are thought to have originated by homoploid hybrid speciation (HHS), but in only a handful of cases are details of the process known. A previous study indicated that Picea purpurea, a conifer in the Qinghai-Tibet Plateau (QTP), originated through HHS from P. likiangensis and P. wilsonii. To investigate this origin in more detail, we analysed transcriptome data for 114 individuals collected from 34 populations of the three Picea species from their core distributions in the QTP. Phylogenetic, principal component and admixture analyses of nuclear SNPs showed the species to be delimited genetically and that P. purpurea was admixed with approximately 60% of its ancestry derived from P. wilsonii and 40% from P. likiangensis. Coalescent simulations revealed the best-fitting model of origin involved formation of an intermediate hybrid lineage between P. likiangensis and P. wilsonii approximately 6 million years ago (mya), which backcrossed to P. wilsonii to form P. purpurea approximately one mya. The intermediate hybrid lineage no longer exists and is referred to as a "ghost" lineage. Our study emphasizes the power of population genomic analysis combined with coalescent analysis for reconstructing the stages involved in the origin of a homoploid hybrid species over an extended period. In contrast to other studies, we show that these stages can in some instances span a relatively long period of evolutionary time.
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Affiliation(s)
- Dafu Ru
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Yongshuai Sun
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China.,CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, PR China
| | - Donglei Wang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Yang Chen
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Tianjing Wang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | - Quanjun Hu
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
| | | | - Jianquan Liu
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, PR China
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McKown AD, Klápště J, Guy RD, El-Kassaby YA, Mansfield SD. Ecological genomics of variation in bud-break phenology and mechanisms of response to climate warming in Populus trichocarpa. THE NEW PHYTOLOGIST 2018; 220:300-316. [PMID: 29963703 DOI: 10.1111/nph.15273] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 05/14/2018] [Indexed: 05/10/2023]
Abstract
Spring bud-break phenology is a critical adaptive feature common to temperate perennial woody plants. Understanding the molecular underpinnings of variation in bud-break is important for elucidating adaptive evolution and predicting outcomes relating to climate change. Field and controlled growth chamber tests were used to assess population-wide patterns in bud-break from wild-sourced black cottonwood (Populus trichocarpa) genotypes. We conducted a genome-wide association study (GWAS) with single nucleotide polymorphisms (SNPs) derived from whole genome sequencing to test for loci underlying variation in bud-break. Bud-break had a quadratic relationship with latitude, where southern- and northern-most provenances generally broke bud earlier than those from central parts of the species' range. Reduced winter chilling increased population-wide variation in bud-break, whereas greater chilling decreased variation. GWAS uncovered 16 loci associated with bud-break. Phenotypic changes connected with allelic variation were replicated in an independent set of P. trichocarpa trees. Despite phenotypic similarities, genetic profiles between southern- and northern-most genotypes were dissimilar based on our GWAS-identified SNPs. We propose that the GWAS-identified loci underpin the geographical pattern in P. trichocarpa and that variation in bud-break reflects different selection for winter chilling and heat sum accumulation, both of which can be affected by climate warming.
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Affiliation(s)
- Athena D McKown
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jaroslav Klápště
- Department of Dendrology and Forest Tree Breeding, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, 165 21, Czech Republic
- Scion (New Zealand Forest Research Institute Ltd), Whakarewarewa, Rotorua, 3046, New Zealand
| | - Robert D Guy
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Shawn D Mansfield
- Department of Wood Science, Faculty of Forestry, Forest Sciences Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Chhatre VE, Evans LM, DiFazio SP, Keller SR. Adaptive introgression and maintenance of a trispecies hybrid complex in range‐edge populations of
Populus. Mol Ecol 2018; 27:4820-4838. [DOI: 10.1111/mec.14820] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Vikram E. Chhatre
- Department of Plant Biology University of Vermont Burlington Vermont
| | - Luke M. Evans
- Department of Ecology and Evolutionary Biology Institute of Behavioral Genetics University of Colorado Boulder Colorado
| | | | - Stephen R. Keller
- Department of Plant Biology University of Vermont Burlington Vermont
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46
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Bradburd GS, Coop GM, Ralph PL. Inferring Continuous and Discrete Population Genetic Structure Across Space. Genetics 2018; 210:33-52. [PMID: 30026187 PMCID: PMC6116973 DOI: 10.1534/genetics.118.301333] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/16/2018] [Indexed: 11/23/2022] Open
Abstract
A classic problem in population genetics is the characterization of discrete population structure in the presence of continuous patterns of genetic differentiation. Especially when sampling is discontinuous, the use of clustering or assignment methods may incorrectly ascribe differentiation due to continuous processes (e.g., geographic isolation by distance) to discrete processes, such as geographic, ecological, or reproductive barriers between populations. This reflects a shortcoming of current methods for inferring and visualizing population structure when applied to genetic data deriving from geographically distributed populations. Here, we present a statistical framework for the simultaneous inference of continuous and discrete patterns of population structure. The method estimates ancestry proportions for each sample from a set of two-dimensional population layers, and, within each layer, estimates a rate at which relatedness decays with distance. This thereby explicitly addresses the "clines versus clusters" problem in modeling population genetic variation, and remedies some of the overfitting to which nonspatial models are prone. The method produces useful descriptions of structure in genetic relatedness in situations where separated, geographically distributed populations interact, as after a range expansion or secondary contact. We demonstrate the utility of this approach using simulations and by applying it to empirical datasets of poplars and black bears in North America.
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Affiliation(s)
- Gideon S Bradburd
- Ecology, Evolutionary Biology, and Behavior Graduate Group, Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824
| | - Graham M Coop
- Center for Population Biology, Department of Evolution and Ecology, University of California, Davis, California 95616
| | - Peter L Ralph
- Institute of Ecology and Evolution, Departments of Mathematics and Biology, University of Oregon, Eugene, Oregon 97403
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Dias-Alves T, Mairal J, Blum MGB. Loter: A Software Package to Infer Local Ancestry for a Wide Range of Species. Mol Biol Evol 2018; 35:2318-2326. [PMID: 29931083 PMCID: PMC6107063 DOI: 10.1093/molbev/msy126] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Admixture between populations provides opportunity to study biological adaptation and phenotypic variation. Admixture studies rely on local ancestry inference for admixed individuals, which consists of computing at each locus the number of copies that originate from ancestral source populations. Existing software packages for local ancestry inference are tuned to provide accurate results on human data and recent admixture events. Here, we introduce Loter, an open-source software package that does not require any biological parameter besides haplotype data in order to make local ancestry inference available for a wide range of species. Using simulations, we compare the performance of Loter to HAPMIX, LAMP-LD, and RFMix. HAPMIX is the only software severely impacted by imperfect haplotype reconstruction. Loter is the less impacted software by increasing admixture time when considering simulated and admixed human genotypes. For simulations of admixed Populus genotypes, Loter and LAMP-LD are robust to increasing admixture times by contrast to RFMix. When comparing length of reconstructed and true ancestry tracts, Loter and LAMP-LD provide results whose accuracy is again more robust than RFMix to increasing admixture times. We apply Loter to individuals resulting from admixture between Populus trichocarpa and Populus balsamifera and lengths of ancestry tracts indicate that admixture took place ∼100 generations ago. We expect that providing a rapid and parameter-free software for local ancestry inference will make more accessible genomic studies about admixture processes.
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Affiliation(s)
| | - Julien Mairal
- CNRS, Institute of Engineering Univ. Grenoble Alpes, LJK, Univ. Grenoble Alpes, Inria, Grenoble, France
| | - Michael G B Blum
- CNRS, TIMC-IMAG UMR 5525, Univ. Grenoble Alpes, Grenoble, France
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48
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Suarez-Gonzalez A, Hefer CA, Lexer C, Cronk QCB, Douglas CJ. Scale and direction of adaptive introgression between black cottonwood (Populus trichocarpa) and balsam poplar (P. balsamifera). Mol Ecol 2018; 27:1667-1680. [DOI: 10.1111/mec.14561] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 02/17/2018] [Accepted: 02/23/2018] [Indexed: 12/31/2022]
Affiliation(s)
| | - Charles A. Hefer
- Department of Botany; University of British Columbia; Vancouver BC Canada
| | - Christian Lexer
- Department of Botany and Biodiversity Research; University of Vienna; Vienna Austria
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49
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Ortego J, Gugger PF, Sork VL. Genomic data reveal cryptic lineage diversification and introgression in Californian golden cup oaks (section Protobalanus). THE NEW PHYTOLOGIST 2018; 218:804-818. [PMID: 29274282 DOI: 10.1111/nph.14951] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 11/14/2017] [Indexed: 05/15/2023]
Abstract
Here we study hybridization, introgression and lineage diversification in the widely distributed canyon live oak (Quercus chrysolepis) and the relict island oak (Q. tomentella), two Californian golden cup oaks with an intriguing biogeographical history. We employed restriction-site-associated DNA sequencing and integrated phylogenomic and population genomic analyses to study hybridization and reconstruct the evolutionary past of these taxa. Our analyses revealed the presence of two cryptic lineages within Q. chrysolepis. One of these lineages shares its most recent common ancestor with Q. tomentella, supporting the paraphyly of Q. chrysolepis. The split of these lineages was estimated to take place during the late Pliocene or the early Pleistocene, a time corresponding well with the common presence of Q. tomentella in the fossil records of continental California. Analyses also revealed historical hybridization among lineages, high introgression from Q. tomentella into Q. chrysolepis in their current area of sympatry, and widespread admixture between the two lineages of Q. chrysolepis in contact zones. Our results support that the two lineages of Q. chrysolepis behave as a single functional species phenotypically and ecologically well differentiated from Q. tomentella, a situation that can be only accommodated considering hybridization and speciation as a continuum with diffuse limits.
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Affiliation(s)
- Joaquín Ortego
- Department of Integrative Ecology, Estación Biológica de Doñana, EBD-CSIC, Avda. Américo Vespucio 26, Seville, E-41092, Spain
| | - Paul F Gugger
- Appalachian Laboratory, University of Maryland Center for Environmental Science, 301 Braddock Road, Frostburg, MD, 21532, USA
| | - Victoria L Sork
- Department of Ecology and Evolutionary Biology, University of California, Box 957239, Los Angeles, CA, 90095, USA
- Institute of the Environment and Sustainability, University of California, Box 951496, Los Angeles, CA, 90095-1496, USA
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50
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Tsai CJ, Harding SA, Cooke JEK. Branching out: a new era of investigating physiological processes in forest trees using genomic tools. TREE PHYSIOLOGY 2018; 38:303-310. [PMID: 29506180 DOI: 10.1093/treephys/tpy026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 02/14/2018] [Indexed: 06/08/2023]
Affiliation(s)
- Chung-Jui Tsai
- Warnell School of Forestry and Natural Resources, Department of Genetics and Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Scott A Harding
- Warnell School of Forestry and Natural Resources, Department of Genetics and Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Janice E K Cooke
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9
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