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Javid M, Ullah S, Amin F, Shah W, Malik T, Alwahibi MS, Waheed A, Ercisli S, Ali B. Computing the effects of temperature and osmotic stress on the seed germination of Helianthus annuus L. by using a mathematical model. Sci Rep 2024; 14:9978. [PMID: 38693252 PMCID: PMC11063032 DOI: 10.1038/s41598-024-60015-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/17/2024] [Indexed: 05/03/2024] Open
Abstract
An extremely important oil crop in the world, Helianthus annuus L. is one of the world's most significant members of the Asteraceae family. The rate and extent of seed germination and agronomic features are consistently affecting by temperature (T) and changes in water potential (ψ). A broad hydrothermal time model with T and ψ components could explain sunflower responses over suboptimal T and ψ. A lab experiment was performed using the HTT model to discover both T and ψ and their interactive effects on sunflower germination and also to figure out the cardinal Ts values. The sunflower seeds were germinated at temperatures (15 °C, 20 °C, 25 °C and 30 °C); each Ts had five constant ψs of 0, 0.3, 0.6, 0.9, and 1.2 MPa via PEG 6000 as osmotic stress inducer. The results revealed that highest germination index was found in seed grown at 20 °C in distilled water (0 MPa) and the lowest at 30 °C with osmotic stress of (- 1.2 MPa). The highest value of germination rate index was found in seed grown at 20 °C in distilled water (0 MPa) and the lowest at 15 °C with an osmotic stress of (- 1.2 MPa). In conclusion, water potential, temperature, and their interactions have a considerable impact on seed germination rate, and other metrics (GI, SVI-I, GRI, GE, SVI-II, and MGT). Seeds sown at 20 °C with zero water potential showed high germination metrics such as GE, GP, GRI, and T50%. The maximum value to TTsub noted at 30 °C in - 0.9 MPa osmotic stress and the minimum value was calculated at 15 °C in - 1.2 MPa osmotic stress. The result of TTsupra recorded highest at 15 °C in controlled group (0 MPa). Moreover, θH was highest at 30 °C in controlled condition (0 MPa) and minimum value was observed at 20 °C under - 1.2 MPa osmotic stress. The value of θHTT were maximum at 30 °C in controlled group (0 MPa) and minimum value was recorded at 15 °C under - 1.2 MPa osmotic potential. The base, optimum and ceiling temperatures for sunflower germination metrics in this experiment were noted 6.8, 20 and 30 °C respectively.
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Affiliation(s)
- Maryam Javid
- Department of Botany, University of Peshawar, Peshawar, 25120, Pakistan
| | - Sami Ullah
- Department of Botany, University of Peshawar, Peshawar, 25120, Pakistan.
| | - Fazal Amin
- Department of Botany, University of Peshawar, Peshawar, 25120, Pakistan
| | - Wadood Shah
- Biological Sciences Research Division, Pakistan Forest Institute, Peshawar, 25120, Pakistan
| | - Tabarak Malik
- Department of Biomedical Sciences, Institute of Health, Jimma University, 378, Jimma, Ethiopia.
- Adjucnt Faculty, Division of Research & Development, Lovely Professional University, Phagwara, India.
| | - Mona S Alwahibi
- Department of Botany and Microbiology, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia
| | - Abdul Waheed
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518124, China
| | - Sezai Ercisli
- Department of Horticulture, Agricultural Faculty, Ataturk University, 25240, Erzurum, Türkiye
- HGF Agro, Ata Teknokent, 25240, Erzurum, Türkiye
| | - Baber Ali
- Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan
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Innes PA, Goebl AM, Smith CCR, Rosenberger K, Kane NC. Gene expression and alternative splicing contribute to adaptive divergence of ecotypes. Heredity (Edinb) 2024; 132:120-132. [PMID: 38071268 PMCID: PMC10924094 DOI: 10.1038/s41437-023-00665-y] [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: 02/28/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 03/10/2024] Open
Abstract
Regulation of gene expression is a critical link between genotype and phenotype explaining substantial heritable variation within species. However, we are only beginning to understand the ways that specific gene regulatory mechanisms contribute to adaptive divergence of populations. In plants, the post-transcriptional regulatory mechanism of alternative splicing (AS) plays an important role in both development and abiotic stress response, making it a compelling potential target of natural selection. AS allows organisms to generate multiple different transcripts/proteins from a single gene and thus may provide a source of evolutionary novelty. Here, we examine whether variation in alternative splicing and gene expression levels might contribute to adaptation and incipient speciation of dune-adapted prairie sunflowers in Great Sand Dunes National Park, Colorado, USA. We conducted a common garden experiment to assess transcriptomic variation among ecotypes and analyzed differential expression, differential splicing, and gene coexpression. We show that individual genes are strongly differentiated for both transcript level and alternative isoform proportions, even when grown in a common environment, and that gene coexpression networks are disrupted between ecotypes. Furthermore, we examined how genome-wide patterns of sequence divergence correspond to divergence in transcript levels and isoform proportions and find evidence for both cis and trans-regulation. Together, our results emphasize that alternative splicing has been an underappreciated mechanism providing source material for natural selection at short evolutionary time scales.
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Affiliation(s)
- Peter A Innes
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA.
| | - April M Goebl
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA
- Research and Conservation Department, Denver Botanic Gardens, Denver, CO, USA
| | - Chris C R Smith
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Kaylee Rosenberger
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA
| | - Nolan C Kane
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, CO, USA
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Goebl AM, Kane NC, Doak DF, Rieseberg LH, Ostevik KL. Adaptation to distinct habitats is maintained by contrasting selection at different life stages in sunflower ecotypes. Mol Ecol 2024; 33:e16785. [PMID: 36374153 DOI: 10.1111/mec.16785] [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: 07/12/2022] [Revised: 10/20/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022]
Abstract
Conspecific populations living in adjacent but contrasting microenvironments represent excellent systems for studying natural selection. These systems are valuable because gene flow is expected to force genetic homogeneity except at loci experiencing divergent selection. A history of reciprocal transplant and common garden studies in such systems, and a growing number of genomic studies, have contributed to understanding how selection operates in natural populations. While selection can vary across different fitness components and life stages, few studies have investigated how this ultimately affects allele frequencies and the maintenance of divergence between populations. Here, we study two sunflower ecotypes in distinct, adjacent habitats by combining demographic models with genome-wide sequence data to estimate fitness and allele frequency change at multiple life stages. This framework allows us to estimate that only local ecotypes are likely to experience positive population growth (λ > 1) and that the maintenance of divergent adaptation appears to be mediated via habitat- and life stage-specific selection. We identify genetic variation, significantly driven by loci in chromosomal inversions, associated with different life history strategies in neighbouring ecotypes that optimize different fitness components and may contribute to the maintenance of distinct ecotypes.
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Affiliation(s)
- April M Goebl
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
| | - Nolan C Kane
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
| | - Daniel F Doak
- Environmental Studies Programme, University of Colorado, Boulder, Colorado, USA
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kate L Ostevik
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Evolution, Ecology and Organismal Biology, University of California Riverside, Riverside, California, USA
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Kou Y, Fan D, Cheng S, Yang Y, Wang M, Wang Y, Zhang Z. Peripatric speciation within Torreya fargesii (Taxaceae) in the Hengduan Mountains inferred from multi-loci phylogeography. BMC Ecol Evol 2023; 23:74. [PMID: 38087226 PMCID: PMC10714551 DOI: 10.1186/s12862-023-02183-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND The Hengduan Mountains (HDM) are one of the major global biodiversity hotspots in the world. Several evolutionary scenarios, especially in-situ diversification, have been proposed to account for the high species richness of temperate plants. However, peripatric speciation, an important mode of allopatric speciation, has seldom been reported in this region. RESULTS Here, two chloroplast DNA regions and 14 nuclear loci were sequenced for 112 individuals from 10 populations of Torreya fargesii var. fargesii and 63 individuals from 6 populations of T. fargesii var. yunnanensis. Population genetic analyses revealed that the two varieties are well differentiated genetically (FST, 0.5765) and have uneven genetic diversity (π, 0.00221 vs. 0.00073 on an average of nuclear loci). The gene genealogical relationship showed that T. fargesii var. yunnanensis is inferred as derived from T. fargesii var. fargesii, which was further supported by the coalescent simulations (DIYABC, fastsimcoal2 and IMa2). By the coalescent simulations, the divergence time (~ 2.50-3.65 Ma) and the weak gene flow between the two varieties were detected. The gene flow was asymmetrical and only occurred in later stages of divergence, which is caused by second contact due to the population expansion (~ 0.61 Ma) in T. fargesii var. fargesii. In addition, niche modeling indicated that the two varieties are differentiated geographically and ecologically and have unbalanced distribution range. CONCLUSIONS Overall, T. fargesii var. fargesii is always parapatric with respect to T. fargesii var. yunnanensis, and the latter derived from the former in peripatry of the HDM following a colonization from central China during the late Pliocene. Our findings demonstrate that peripatric speciation following dispersal events may be an important evolutionary scenario for the formation of biodiversity hotspot of the HDM.
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Affiliation(s)
- Yixuan Kou
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Normal University, Ministry of Education, Guilin, China
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China
| | - Dengmei Fan
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China
| | - Shanmei Cheng
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China
| | - Yi Yang
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China
| | - Meixia Wang
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China
| | - Yujin Wang
- State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, China.
| | - Zhiyong Zhang
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Guangxi Normal University, Ministry of Education, Guilin, China.
- Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin, Guangxi Normal University, Guilin, China.
- Laboratory of Subtropical Biodiversity, Jiangxi Agricultural University, Nanchang, China.
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Rutherford S, Rossetto M, Bragg JG, Wan JSH. Where to draw the boundaries? Using landscape genomics to disentangle the scribbly gum species complex. AMERICAN JOURNAL OF BOTANY 2023; 110:e16245. [PMID: 37747108 DOI: 10.1002/ajb2.16245] [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: 02/10/2023] [Revised: 09/18/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023]
Abstract
PREMISE Species delimitation is an integral part of evolution and ecology and is vital in conservation science. However, in some groups, species delimitation is difficult, especially where ancestral relationships inferred from morphological or genetic characters are discordant, possibly due to a complicated demographic history (e.g., recent divergences between lineages). Modern genetic techniques can take into account complex histories to distinguish species at a reasonable cost and are increasingly used in numerous applications. We focus on the scribbly gums, a group of up to five closely related and morphologically similar "species" within the eucalypts. METHODS Multiple populations of each recognized scribbly gum species were sampled over a wide region across climates, and genomewide scans were used to resolve species boundaries. RESULTS None of the taxa were completely divergent, and there were two genetically distinct entities: the inland distributed Eucalyptus rossii and a coastal conglomerate consisting of four species forming three discernible, but highly admixed groups. Divergence among taxa was likely driven by temporal vicariant processes resulting in partial separation across biogeographic barriers. High interspecific gene flow indicated separated taxa reconnected at different points in time, blurring species boundaries. CONCLUSIONS Our results highlight the need for genetic screening when dealing with closely related taxonomic entities, particularly those with modest morphological differences. We show that high-throughput sequencing can be effective at identifying species groupings and processes driving divergence, even in the most taxonomically complex groups, and be used as a standard practice for disentangling species complexes.
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Affiliation(s)
- Susan Rutherford
- Department of Environmental Science, College of Science, Mathematics and Technology, Wenzhou-Kean University, Wenzhou, Zhejiang Province, China
- Department of Environmental and Sustainability Sciences, The Dorothy and George Hennings College of Science, Mathematics and Technology, Kean University, Union, NJ, USA
- School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu Province, China
- Research Centre for Ecosystem Resilience, Australian Institute of Botanic Science, Royal Botanic Garden Sydney, Mrs Macquaries Road, Sydney, New South Wales, Australia
- Zhejiang Bioinformatics International Science and Technology Cooperation Center, Wenzhou, Zhejiang Province, China
| | - Maurizio Rossetto
- Research Centre for Ecosystem Resilience, Australian Institute of Botanic Science, Royal Botanic Garden Sydney, Mrs Macquaries Road, Sydney, New South Wales, Australia
| | - Jason G Bragg
- Research Centre for Ecosystem Resilience, Australian Institute of Botanic Science, Royal Botanic Garden Sydney, Mrs Macquaries Road, Sydney, New South Wales, Australia
| | - Justin S H Wan
- School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu Province, China
- Research Centre for Ecosystem Resilience, Australian Institute of Botanic Science, Royal Botanic Garden Sydney, Mrs Macquaries Road, Sydney, New South Wales, Australia
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6
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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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Caeiro-Dias G, Brelsford A, Meneses-Ribeiro M, Crochet PA, Pinho C. Hybridization in late stages of speciation: Strong but incomplete genome-wide reproductive isolation and 'large Z-effect' in a moving hybrid zone. Mol Ecol 2023. [PMID: 37316984 DOI: 10.1111/mec.17035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 04/27/2023] [Accepted: 05/12/2023] [Indexed: 06/16/2023]
Abstract
In organisms reproducing sexually, speciation occurs when increasing divergence results in pre- or post-zygotic reproductive isolation between lineages. Studies focusing on reproductive isolation origin in early stages of speciation are common and many rely on genomic scans to infer introgression providing limited information on the genomic architecture of reproductive isolation long-term maintenance. This study analyses a natural hybrid zone between two species in a late stage of speciation. We used ddRADseq genotyping in the contact between Podarcis bocagei and P. carbonelli to examine admixture extent, analyse hybrid zone stability and assess genome-wide variation in selection against introgression. We confirmed strong but incomplete reproductive isolation in a bimodal hybrid zone. New findings revealed population genetic structure within P. carbonelli in the contact zone; geographical and genomic clines analysis suggested strong selection against gene flow, but a relatively small proportion of the loci can introgress, mostly within the narrow contact zone. However, geographical clines revealed that a few introgressed loci show signs of potential positive selection, particularly into P. bocagei. Geographical clines also detected a signal of hybrid zone movement towards P. bocagei distribution. Genomic cline analysis revealed heterogeneous patterns of introgression among loci within the syntopy zone, but the majority maintain a strong association with the genomic background of origin. However, incongruences between both cline approaches were found, potentially driven by confounding effects on genomic clines. Last, an important role of the Z chromosome in reproductive isolation is suggested. Importantly, overall patterns of restricted introgression seem to result from numerous strong intrinsic barriers across the genome.
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Affiliation(s)
- Guilherme Caeiro-Dias
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- CEFE, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France
| | - Alan Brelsford
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Biology Department, University of California Riverside, Riverside, California, USA
| | - Mariana Meneses-Ribeiro
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | - Pierre-André Crochet
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Catarina Pinho
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
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Matias AMA, Popovic I, Thia JA, Cooke IR, Torda G, Lukoschek V, Bay LK, Kim SW, Riginos C. Cryptic diversity and spatial genetic variation in the coral Acropora tenuis and its endosymbionts across the Great Barrier Reef. Evol Appl 2023; 16:293-310. [PMID: 36793689 PMCID: PMC9923489 DOI: 10.1111/eva.13435] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 05/20/2022] [Accepted: 05/29/2022] [Indexed: 11/26/2022] Open
Abstract
Genomic studies are uncovering extensive cryptic diversity within reef-building corals, suggesting that evolutionarily and ecologically relevant diversity is highly underestimated in the very organisms that structure coral reefs. Furthermore, endosymbiotic algae within coral host species can confer adaptive responses to environmental stress and may represent additional axes of coral genetic variation that are not constrained by taxonomic divergence of the cnidarian host. Here, we examine genetic variation in a common and widespread, reef-building coral, Acropora tenuis, and its associated endosymbiotic algae along the entire expanse of the Great Barrier Reef (GBR). We use SNPs derived from genome-wide sequencing to characterize the cnidarian coral host and organelles from zooxanthellate endosymbionts (genus Cladocopium). We discover three distinct and sympatric genetic clusters of coral hosts, whose distributions appear associated with latitude and inshore-offshore reef position. Demographic modelling suggests that the divergence history of the three distinct host taxa ranges from 0.5 to 1.5 million years ago, preceding the GBR's formation, and has been characterized by low-to-moderate ongoing inter-taxon gene flow, consistent with occasional hybridization and introgression typifying coral evolution. Despite this differentiation in the cnidarian host, A. tenuis taxa share a common symbiont pool, dominated by the genus Cladocopium (Clade C). Cladocopium plastid diversity is not strongly associated with host identity but varies with reef location relative to shore: inshore colonies contain lower symbiont diversity on average but have greater differences between colonies as compared with symbiont communities from offshore colonies. Spatial genetic patterns of symbiont communities could reflect local selective pressures maintaining coral holobiont differentiation across an inshore-offshore environmental gradient. The strong influence of environment (but not host identity) on symbiont community composition supports the notion that symbiont community composition responds to habitat and may assist in the adaptation of corals to future environmental change.
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Affiliation(s)
- Ambrocio Melvin A. Matias
- Institute of BiologyUniversity of the Philippines DilimanQuezon CityPhilippines
- School of Biological SciencesThe University of QueenslandSt. LuciaQueenslandAustralia
| | - Iva Popovic
- School of Biological SciencesThe University of QueenslandSt. LuciaQueenslandAustralia
| | - Joshua A. Thia
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkevilleVictoriaAustralia
| | - Ira R. Cooke
- College of Public Health, Medical and Veterinary SciencesJames Cook UniversityTownsvilleQueenslandAustralia
| | - Gergely Torda
- ARC Centre of Excellence for Coral Reef StudiesJames Cook UniversityTownsvilleQueenslandAustralia
| | - Vimoksalehi Lukoschek
- ARC Centre of Excellence for Coral Reef StudiesJames Cook UniversityTownsvilleQueenslandAustralia
- Gold Coast University HospitalQLD HealthSouthportQueenslandAustralia
| | - Line K. Bay
- Australian Institute of Marine ScienceTownsvilleQueenslandAustralia
| | - Sun W. Kim
- School of Biological SciencesThe University of QueenslandSt. LuciaQueenslandAustralia
| | - Cynthia Riginos
- School of Biological SciencesThe University of QueenslandSt. LuciaQueenslandAustralia
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9
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Zhang J, Zhang S, Zheng Z, Lu Z, Yang Y. Genomic divergence between two sister Ostrya species through linked selection and recombination. Ecol Evol 2022; 12:e9611. [PMID: 36540075 PMCID: PMC9754895 DOI: 10.1002/ece3.9611] [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: 09/06/2022] [Revised: 11/16/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022] Open
Abstract
Studying the evolution of genomic divergence between lineages is a topical issue in evolutionary biology. However, the evolutionary forces that shape the heterogeneous divergence of the genomic landscape are still poorly understood. Here, two wind-pollinated sister-species (Ostrya japonica and O. chinensis) are used to explore what these potential forces might be. A total of 40 individuals from 16 populations across their main distribution areas in China were sampled for genome-wide resequencing. Population demography analyses revealed that these two sister-species diverged at 3.06-4.43 Mya. Both population contraction and increased gene flow were detected during glacial periods, suggesting secondary contact at those times. All three parameters (D XY, π, and ρ) decreased in those regions showing high levels of differentiation (F ST). These findings indicate that linked selection and recombination played a key role in the genomic heterogeneous differentiation between the two Ostrya species. Genotype-environment association analyses showed that precipitation was the most important ecological factor for speciation. Such environmentally related genes and positive selection genes may have contributed to local adaptation and the maintenance of species boundaries.
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Affiliation(s)
- Jin Zhang
- State Key Laboratory of Grassland Agro‐Ecosystems, College of EcologyLanzhou UniversityLanzhouChina
| | - Shangzhe Zhang
- State Key Laboratory of Grassland Agro‐Ecosystems, College of EcologyLanzhou UniversityLanzhouChina
| | - Zeyu Zheng
- State Key Laboratory of Grassland Agro‐Ecosystems, College of EcologyLanzhou UniversityLanzhouChina
| | - Zhiqiang Lu
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesMenglaChina
| | - Yongzhi Yang
- State Key Laboratory of Grassland Agro‐Ecosystems, College of EcologyLanzhou UniversityLanzhouChina
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10
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Osmolovsky I, Shifrin M, Gamliel I, Belmaker J, Sapir Y. Eco-Geography and Phenology Are the Major Drivers of Reproductive Isolation in the Royal Irises, a Species Complex in the Course of Speciation. PLANTS (BASEL, SWITZERLAND) 2022; 11:3306. [PMID: 36501345 PMCID: PMC9739335 DOI: 10.3390/plants11233306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/30/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
The continuous nature of speciation implies that different species are found at different stages of divergence, from no- to complete reproductive isolation. This process and its underlying mechanisms are best viewed in incipient species. Moreover, the species complex can offer unique insight into how reproductive isolation (RI) has evolved. The royal irises (Iris section Oncocyclus) are a young group of species in the course of speciation, providing an ideal system for speciation study. We quantified pre- and post-zygotic reproductive barriers between the eight Israeli species of this complex and estimated the total RI among them. We tested for both pre-pollination and post-pollination reproductive barriers. Pre-pollination barriers, i.e., eco-geographic divergence and phenological differentiation were the major contributors to RI among the Iris species. On the other hand, post-pollination barriers, namely pollen-stigma interactions, fruit set, and seed viability had negligible contributions to total RI. The strength of RI was not uniform across the species complex, suggesting that species may have diverged at different rates. Overall, this study in a young, recently diverged group of species provides insight into the first steps of speciation, suggesting a crucial role of the pre-zygotic barriers.
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Affiliation(s)
- Inna Osmolovsky
- The Botanical Garden, School of Plant Science and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Mariana Shifrin
- The Botanical Garden, School of Plant Science and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Inbal Gamliel
- School of Zoology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jonathan Belmaker
- School of Zoology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yuval Sapir
- The Botanical Garden, School of Plant Science and Food Security, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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11
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Otero A, Vargas P, Fernández-Mazuecos M, Jiménez-Mejías P, Valcárcel V, Villa-Machío I, Hipp AL. A snapshot of progenitor-derivative speciation in Iberodes (Boraginaceae). Mol Ecol 2022; 31:3192-3209. [PMID: 35390211 DOI: 10.1111/mec.16459] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 03/27/2022] [Accepted: 04/01/2022] [Indexed: 11/28/2022]
Abstract
Traditional classification of speciation modes has focused on physical barriers to gene flow. Allopatric speciation with complete reproductive isolation is viewed as the most common mechanism of speciation. Parapatry and sympatry, by contrast, entail speciation in the face of ongoing gene flow, making them more difficult to detect. The genus Iberodes (Boraginaceae, NW Europe) comprises five species with contrasting morphological traits, habitats, and species distributions. Based on the predominance of narrow and geographically distant endemic species, we hypothesized that geographic barriers were responsible for most speciation events in Iberodes. We undertook an integrative study including: (i) phylogenomics through restriction-site associated DNA sequencing, (ii) genetic structure analyses, (iii) demographic modeling, (iv) morphometrics, and (v) climatic niche modeling and niche overlap analysis. Results revealed a history of recurrent progenitor-derivative speciation manifested by a paraphyletic pattern of nested species differentiation. Budding speciation mediated by ecological differentiation is suggested for the coastal lineage, deriving from the inland widespread I. linifolia during Late Pliocene. Meanwhile, geographic isolation followed by niche shifts are suggested for the more recent differentiation of the coastland taxa. Our work provides a model for distinguishing speciation via ecological differentiation of peripheral, narrowly endemic I. kuzinskyanae and I. littoralis from a widespread extant ancestor, I. linifolia. Ultimately, our results illustrate a case of Pliocene speciation in the probable absence of geographic barriers and get away from the traditional cladistic perspective of speciation as producing two species from an extinct ancestor, thus reminding us that phylogenetic trees tell only part of the story.
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Affiliation(s)
- Ana Otero
- Grainger Bioinformatics Center, Department of Science and Education, The Field Museum, 1400 S. DuSable Lake Shore Dr, 60605, Chicago, Illinois, USA.,Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC). Pza. de Murillo, 28014, Madrid, Spain
| | - Pablo Vargas
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC). Pza. de Murillo, 28014, Madrid, Spain
| | - Mario Fernández-Mazuecos
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC). Pza. de Murillo, 28014, Madrid, Spain.,Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Departamento de Biología (Botánica), Universidad Autónoma de Madrid, C/ Darwin, 2, 28049, Madrid, Spain
| | - Pedro Jiménez-Mejías
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Departamento de Biología (Botánica), Universidad Autónoma de Madrid, C/ Darwin, 2, 28049, Madrid, Spain
| | - Virginia Valcárcel
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Departamento de Biología (Botánica), Universidad Autónoma de Madrid, C/ Darwin, 2, 28049, Madrid, Spain
| | - Irene Villa-Machío
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC). Pza. de Murillo, 28014, Madrid, Spain
| | - Andrew L Hipp
- Grainger Bioinformatics Center, Department of Science and Education, The Field Museum, 1400 S. DuSable Lake Shore Dr, 60605, Chicago, Illinois, USA.,The Morton Arboretum, 4100 Illinois Route 53, 60532, Lisle, Illinois, USA
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12
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Villalobos-Barrantes HM, Meriño BM, Walter HE, Guerrero PC. Independent Evolutionary Lineages in a Globular Cactus Species Complex Reveals Hidden Diversity in a Central Chile Biodiversity Hotspot. Genes (Basel) 2022; 13:genes13020240. [PMID: 35205285 PMCID: PMC8872226 DOI: 10.3390/genes13020240] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 02/01/2023] Open
Abstract
Unraveling the processes involved in the origin of a substantial fraction of biodiversity can be a particularly difficult task in groups of similar, and often convergent, morphologies. The genus Eriosyce (Cactaceae) might present a greater specific diversity since much of its species richness might be hidden in morphological species complexes. The aim of this study was to investigate species delimitation using the molecular data of the globose cacti “E. curvispina”, which harbor several populations of unclear evolutionary relationships. We ran phylogenetic inferences on 87 taxa of Eriosyce, including nine E. curvispina populations, and by analyzing three plastid noncoding introns, one plastid and one nuclear gene. Additionally, we developed 12 new pairs of nuclear microsatellites to evaluate the population-level genetic structure. We identified four groups that originated in independent cladogenetic events occurring at different temporal depths; these groups presented high genetic diversity, and their populations were genetically structured. These results suggest a complex evolutionary history in the origin of globular cacti, with independent speciation events occurring at different time spans. This cryptic richness is underestimated in the Mediterranean flora of central Chile, and thus unique evolutionary diversity could be overlooked in conservation and management actions.
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Affiliation(s)
- Heidy M. Villalobos-Barrantes
- Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción 4030000, Chile; (H.M.V.-B.); (B.M.M.)
- Escuela de Química, Universidad de Costa Rica, San José 11501-2060, Costa Rica
- Centro de Investigación en Biología Celular y Molecular, Universidad de Costa Rica, San José 11501-2060, Costa Rica
| | - Beatriz M. Meriño
- Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción 4030000, Chile; (H.M.V.-B.); (B.M.M.)
- Institute of Ecology and Biodiversity (IEB), Concepción 4030000, Chile
| | - Helmut E. Walter
- The EXSIS Project: Cactaceae Ex-Situ & In-Situ Conservation, 31860 Emmerthal, Germany;
| | - Pablo C. Guerrero
- Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción 4030000, Chile; (H.M.V.-B.); (B.M.M.)
- Institute of Ecology and Biodiversity (IEB), Concepción 4030000, Chile
- Millennium Institute Biodiversity of Antarctic and Sub-Antarctic Ecosystems (BASE), Santiago 7800003, Chile
- Correspondence:
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13
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Ullah R, Sher S, Muhammad Z, Afriq Jan S, Nafees M. Modulating response of sunflower (Hellianthus annuus) to induced salinity stress through application of engineered urea functionalized hydroxyapatite nanoparticles. Microsc Res Tech 2021; 85:244-252. [PMID: 34369637 DOI: 10.1002/jemt.23900] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/12/2021] [Accepted: 07/25/2021] [Indexed: 11/08/2022]
Abstract
Agro-nanotechnology aims to improve the quality and quantity of plants and plant products while preserving environmental health. Contemporary anecdotal studies that provide representation of the use of nanostructures as fertilizers, pesticides, and plant growth regulators have highlighted the need to determine the effect of such modified nanofertilizers on transforming plant yield under abiotic stress. Present study was performed to modulate the physiological response of Hellianthus annuus through the application of Urea capped hydroxyapatite nanoparticles (Urea-HANPs) in stressed environment. Hydroxyapatite nanoparticles were synthesized via co-precipitation method, functionalized with urea and characterized through a series of contemporary techniques of transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. We observed that Urea-HANPs significantly (p < .05) ameliorated resistivity in plant to osmotic stress by enhancing agronomic and physiobiochemical attributes. Elevated chlorophyll contents were reported from tested leaves treated with Urea-HANPs in T6 (0.05 M NaCl + 10 μg/ml Urea-HANP) under induced salinity stress. Data revealed significant decrease in osmolytes at T3 (0.1 M NaCl), and T4 (0.2 M NaCl) which was significantly ameliorated in T9 (0.1 M NaCl + 10 μg/ml Urea-HANPs) and T12 (0.2 M NaCl + 10 μg/ml Urea-HANPs). The antioxidant system was boosted up by the application of Urea-HANPs preventing the plant from oxidative stress by scavenging reactive oxygen species (ROS). It has been concluded that alleviation in impact of osmotic stress on plant through the use of Urea-HANPs was coupled with elevation in photosynthetic performance, stimulation of osmolytes and boosting antioxidant system of plants.
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Affiliation(s)
- Rehman Ullah
- Plant Physiology Lab., Department of Botany, University of Peshawar, Peshawar, Pakistan
| | - Safia Sher
- Plant Physiology Lab., Department of Botany, University of Peshawar, Peshawar, Pakistan
| | - Zahir Muhammad
- Plant Physiology Lab., Department of Botany, University of Peshawar, Peshawar, Pakistan
| | - Saiqa Afriq Jan
- Plant Physiology Lab., Department of Botany, University of Peshawar, Peshawar, Pakistan
| | - Muhammad Nafees
- Plant Physiology Lab., Department of Botany, University of Peshawar, Peshawar, Pakistan
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14
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Owens GL, Todesco M, Bercovich N, Légaré JS, Mitchell N, Whitney KD, Rieseberg LH. Standing variation rather than recent adaptive introgression probably underlies differentiation of the texanus subspecies of Helianthus annuus. Mol Ecol 2021; 30:6229-6245. [PMID: 34080243 DOI: 10.1111/mec.16008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 05/17/2021] [Accepted: 05/26/2021] [Indexed: 12/24/2022]
Abstract
The origins of geographic races in wide-ranging species are poorly understood. In Texas, the texanus subspecies of Helianthus annuus has long been thought to have acquired its defining phenotypic traits via introgression from a local congener, H. debilis, but previous tests of this hypothesis were inconclusive. Here, we explore the origins of H. a. texanus using whole genome sequencing data from across the entire range of H. annuus and possible donor species, as well as phenotypic data from a common garden study. We found that although it is morphologically convergent with H. debilis, H. a. texanus has conflicting signals of introgression. Genome wide tests (Patterson's D and TreeMix) only found evidence of introgression from H. argophyllus (sister species to H. annuus and also sympatric), but not H. debilis, with the exception of one individual of 109 analysed. We further scanned the genome for localized signals of introgression using PCAdmix and found minimal but nonzero introgression from H. debilis and significant introgression from H. argophyllus in some populations. Given the paucity of introgression from H. debilis, we argue that the morphological convergence observed in Texas is probably from standing genetic variation. We also found that genomic differentiation in H. a. texanus is mostly driven by large segregating inversions, several of which have signatures of natural selection based on haplotype frequencies.
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Affiliation(s)
- Gregory L Owens
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Marco Todesco
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Natalia Bercovich
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Jean-Sébastien Légaré
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Nora Mitchell
- Department of Biology, University of Wisconsin - Eau Claire, Eau Claire, WI, USA.,Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Kenneth D Whitney
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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15
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Microsatellites as Agents of Adaptive Change: An RNA-Seq-Based Comparative Study of Transcriptomes from Five Helianthus Species. Symmetry (Basel) 2021. [DOI: 10.3390/sym13060933] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mutations that provide environment-dependent selective advantages drive adaptive divergence among species. Many phenotypic differences among related species are more likely to result from gene expression divergence rather than from non-synonymous mutations. In this regard, cis-regulatory mutations play an important part in generating functionally significant variation. Some proposed mechanisms that explore the role of cis-regulatory mutations in gene expression divergence involve microsatellites. Microsatellites exhibit high mutation rates achieved through symmetric or asymmetric mutation processes and are abundant in both coding and non-coding regions in positions that could influence gene function and products. Here we tested the hypothesis that microsatellites contribute to gene expression divergence among species with 50 individuals from five closely related Helianthus species using an RNA-seq approach. Differential expression analyses of the transcriptomes revealed that genes containing microsatellites in non-coding regions (UTRs and introns) are more likely to be differentially expressed among species when compared to genes with microsatellites in the coding regions and transcripts lacking microsatellites. We detected a greater proportion of shared microsatellites in 5′UTRs and coding regions compared to 3′UTRs and non-coding transcripts among Helianthus spp. Furthermore, allele frequency differences measured by pairwise FST at single nucleotide polymorphisms (SNPs), indicate greater genetic divergence in transcripts containing microsatellites compared to those lacking microsatellites. A gene ontology (GO) analysis revealed that microsatellite-containing differentially expressed genes are significantly enriched for GO terms associated with regulation of transcription and transcription factor activity. Collectively, our study provides compelling evidence to support the role of microsatellites in gene expression divergence.
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16
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Hunt HV, Przelomska NAS, Campana MG, Cockram J, Bligh HFJ, Kneale CJ, Romanova OI, Malinovskaya EV, Jones MK. Population genomic structure of Eurasian and African foxtail millet landrace accessions inferred from genotyping-by-sequencing. THE PLANT GENOME 2021; 14:e20081. [PMID: 33543599 PMCID: PMC8638668 DOI: 10.1002/tpg2.20081] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/15/2020] [Indexed: 05/11/2023]
Abstract
Foxtail millet [Setaria italica (L.) P. Beauv.] is the second most important millet species globally and is adapted to cultivation in diverse environments. Like its wild progenitor, green foxtail [S. viridis (L.) P. Beauv.], it is a model species for C4 photosynthetic pathways and stress tolerance genes in related bioenergy crops. We addressed questions regarding the evolution and spread of foxtail millet through a population genomic study of landraces from across its cultivated range in Europe, Asia, and Africa. We sought to determine population genomic structure and the relationship of domesticated lineages relative to green foxtail. Further, we aimed to identify genes involved in environmental stress tolerance that have undergone differential selection between geographical and genetic groups. Foxtail millet landrace accessions (n = 328) and green foxtail accessions (n = 12) were sequenced by genotyping-by-sequencing (GBS). After filtering, 5,677 single nucleotide polymorphisms (SNPs) were retained for the combined foxtail millet-green foxtail dataset and 5,020 for the foxtail millet dataset. We extended geographic coverage of green foxtail by including previously published GBS sequence tags, yielding a 4,515-SNP dataset for phylogenetic reconstruction. All foxtail millet samples were monophyletic relative to green foxtail, suggesting a single origin of foxtail millet, although no group of foxtail millet was clearly the most ancestral. Four genetic clusters were found within foxtail millet, each with a distinctive geographical distribution. These results, together with archaeobotanical evidence, suggest plausible routes of spread of foxtail millet. Selection scans identified nine candidate genes potentially involved in environmental adaptations, particularly to novel climates encountered, as domesticated foxtail millet spread to new altitudes and latitudes.
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Affiliation(s)
- Harriet V. Hunt
- McDonald Institute for Archaeological ResearchUniversity of CambridgeDowning StreetCambridgeCB2 3ERUK
| | - Natalia A. S. Przelomska
- Comparative Plant and Fungal BiologyRoyal Botanic GardensKewRichmondTW9 3AEUK
- Department of AnthropologyNational Museum of Natural HistorySmithsonian InstitutionWashingtonDC20560USA
- Center for Conservation GenomicsSmithsonian's National Zoo and Conservation Biology InstituteSmithsonian InstitutionWashingtonDC20008USA
- Department of ArchaeologyUniversity of CambridgeDowning StreetCambridgeCB2 3DZUK
| | - Michael G. Campana
- Center for Conservation GenomicsSmithsonian's National Zoo and Conservation Biology InstituteSmithsonian InstitutionWashingtonDC20008USA
| | - James Cockram
- The John Bingham LaboratoryNIAB93 Lawrence Weaver RoadCambridgeCB3 0LEUK
| | | | - Catherine J. Kneale
- McDonald Institute for Archaeological ResearchUniversity of CambridgeDowning StreetCambridgeCB2 3ERUK
| | - Olga I. Romanova
- N.I. Vavilov Institute of Plant Genetic Resources (VIR)St. Petersburg190000Russia
| | | | - Martin K. Jones
- Department of ArchaeologyUniversity of CambridgeDowning StreetCambridgeCB2 3DZUK
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17
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Hebda A, Kempf M, Wachowiak W, Pluciński B, Kauzal P, Zwijacz-Kozica T. Hybridization and introgression of native and foreign Sorbus tree species in unique environments of protected mountainous areas. AOB PLANTS 2021; 13:plaa070. [PMID: 33604013 PMCID: PMC7877695 DOI: 10.1093/aobpla/plaa070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
Hybridization and introgression are important processes influencing the genetic diversity and evolution of species. These processes are of particular importance in protected areas, where they can lead to the formation of hybrids between native and foreign species and may ultimately result in the loss of parental species from their natural range. Despite their importance, the contribution of hybridization and introgression to genetic diversity in Sorbus genus remains not fully recognized. We analysed the genetic and morphological variability of several Sorbus species including native (Sorbus aria), foreign (S. intermedia) and potentially hybrid (S. carpatica) individuals from the Polish Carpathian range. Patterns of variation at 13 nuclear microsatellite loci show hybridization between the tested species and confirm the existence of the hybrid form S. carpatica. Biometric analysis on leaves, based of 10 metric features and three parameters, identified several characters for preliminary taxonomic classification; however, none of them could be used as a fully diagnostic marker for faultless annotation of S. intermedia and S. carpatica. The genetic structure analysis indicated complex patterns of population differentiation and its diverse origin. The results allow assessment of genetic variation and identification of parental species participating in hybridization. This knowledge will advance the management of genetic diversity and development of conservation strategies for efficient maintenance of the unique protected ecosystem.
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Affiliation(s)
- Anna Hebda
- Department of Plant Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Kraków, Poland
| | - Marta Kempf
- Department of Genetics and Forest Tree Breeding, Institute of Forest Ecology and Silviculture, Faculty of Forestry, University of Agriculture in Krakow, Kraków, Poland
| | - Witold Wachowiak
- Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland
| | - Bartosz Pluciński
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Kraków, Poland
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18
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Galimberti M, Leuenberger C, Wolf B, Szilágyi SM, Foll M, Wegmann D. Detecting Selection from Linked Sites Using an F-Model. Genetics 2020; 216:1205-1215. [PMID: 33067324 PMCID: PMC7768260 DOI: 10.1534/genetics.120.303780] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/03/2020] [Indexed: 11/18/2022] Open
Abstract
Allele frequencies vary across populations and loci, even in the presence of migration. While most differences may be due to genetic drift, divergent selection will further increase differentiation at some loci. Identifying those is key in studying local adaptation, but remains statistically challenging. A particularly elegant way to describe allele frequency differences among populations connected by migration is the F-model, which measures differences in allele frequencies by population specific FST coefficients. This model readily accounts for multiple evolutionary forces by partitioning FST coefficients into locus- and population-specific components reflecting selection and drift, respectively. Here we present an extension of this model to linked loci by means of a hidden Markov model (HMM), which characterizes the effect of selection on linked markers through correlations in the locus specific component along the genome. Using extensive simulations, we show that the statistical power of our method is up to twofold higher than that of previous implementations that assume sites to be independent. We finally evidence selection in the human genome by applying our method to data from the Human Genome Diversity Project (HGDP).
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Affiliation(s)
- Marco Galimberti
- Department of Biology, University of Fribourg, 1700, Switzerland
- Swiss Institute of Bioinformatics, Fribourg, 1700, Switzerland
| | | | - Beat Wolf
- iCoSys, University of Applied Sciences Western Switzerland, Fribourg, 1700 Switzerland
| | - Sándor Miklós Szilágyi
- Department of Informatics, University of Medicine, Pharmacy, Science and Technology of Târgu Mureş, Târgu Mureş, 540139, Romania
| | - Matthieu Foll
- International Agency for Research on Cancer (IARC/WHO), Section of Genetics, 69372 Lyon, France
| | - Daniel Wegmann
- Department of Biology, University of Fribourg, 1700, Switzerland
- Swiss Institute of Bioinformatics, Fribourg, 1700, Switzerland
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19
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The Genomic Landscape of Divergence Across the Speciation Continuum in Island-Colonising Silvereyes ( Zosterops lateralis). G3-GENES GENOMES GENETICS 2020; 10:3147-3163. [PMID: 32660974 PMCID: PMC7466963 DOI: 10.1534/g3.120.401352] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inferring the evolutionary dynamics at play during the process of speciation by analyzing the genomic landscape of divergence is a major pursuit in population genomics. However, empirical assessments of genomic landscapes under varying evolutionary scenarios that are known a priori are few, thereby limiting our ability to achieve this goal. Here we combine RAD-sequencing and individual-based simulations to evaluate the genomic landscape of divergence in the silvereye (Zosterops lateralis). Using pairwise comparisons that differ in divergence timeframe and the presence or absence of gene flow, we document how genomic patterns accumulate along the speciation continuum. In contrast to previous predictions, our results provide limited support for the idea that divergence accumulates around loci under divergent selection or that genomic islands widen with time. While a small number of genomic islands were found in populations diverging with and without gene flow, in few cases were SNPs putatively under selection tightly associated with genomic islands. The transition from localized to genome-wide levels of divergence was captured using individual-based simulations that considered only neutral processes. Our results challenge the ubiquity of existing verbal models that explain the accumulation of genomic differences across the speciation continuum and instead support the idea that divergence both within and outside of genomic islands is important during the speciation process.
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20
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Muschick M, Soria-Carrasco V, Feder JL, Gompert Z, Nosil P. Adaptive zones shape the magnitude of premating reproductive isolation in Timema stick insects. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190541. [PMID: 32654646 DOI: 10.1098/rstb.2019.0541] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Simpson's fossil-record inspired model of 'adaptive zones' proposes that evolution is dominated by small fluctuations within adaptive zones, occasionally punctuated by larger shifts between zones. This model can help explain why the process of population divergence often results in weak or moderate reproductive isolation (RI), rather than strong RI and distinct species. Applied to the speciation process, the adaptive zones hypothesis makes two inter-related predictions: (i) large shifts between zones are relatively rare, (ii) when large shifts do occur they generate stronger RI than shifts within zones. Here, we use ecological, phylogenetic and behavioural data to test these predictions in Timema stick insects. We show that host use in Timema is dominated by moderate shifts within the systematic divisions of flowering plants and conifers, with only a few extreme shifts between these divisions. However, when extreme shifts occur, they generate greater RI than do more moderate shifts. Our results support the adaptive zones model, and suggest that the net contribution of ecological shifts to diversification is dependent on both their magnitude and frequency. We discuss the generality of our findings in the light of emerging evidence from diverse taxa that the evolution of RI is not always the only factor determining the origin of species diversity. 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)
- Moritz Muschick
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute for Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland.,Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Víctor Soria-Carrasco
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Zach Gompert
- Department of Biology, Utah State University, Logan, UT 84322, USA
| | - Patrik Nosil
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Center for Evolution and Functional Ecology, CNRS, 34000 Montpellier, France
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21
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Massive haplotypes underlie ecotypic differentiation in sunflowers. Nature 2020; 584:602-607. [PMID: 32641831 DOI: 10.1038/s41586-020-2467-6] [Citation(s) in RCA: 186] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/16/2020] [Indexed: 12/22/2022]
Abstract
Species often include multiple ecotypes that are adapted to different environments1. However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations2-4. Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), we identify 37 large (1-100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics. Limited recombination in these haplotype blocks keeps adaptive alleles together, and these regions differentiate sunflower ecotypes. For example, haplotype blocks control a 77-day difference in flowering between ecotypes of the silverleaf sunflower H. argophyllus (probably through deletion of a homologue of FLOWERING LOCUS T (FT)), and are associated with seed size, flowering time and soil fertility in dune-adapted sunflowers. These haplotypes are highly divergent, frequently associated with structural variants and often appear to represent introgressions from other-possibly now-extinct-congeners. These results highlight a pervasive role of structural variation in ecotypic adaptation.
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22
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Huang K, Andrew RL, Owens GL, Ostevik KL, Rieseberg LH. Multiple chromosomal inversions contribute to adaptive divergence of a dune sunflower ecotype. Mol Ecol 2020; 29:2535-2549. [PMID: 32246540 DOI: 10.1111/mec.15428] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
Both models and case studies suggest that chromosomal inversions can facilitate adaptation and speciation in the presence of gene flow by suppressing recombination between locally adapted alleles. Until recently, however, it has been laborious and time-consuming to identify and genotype inversions in natural populations. Here we apply RAD sequencing data and newly developed population genomic approaches to identify putative inversions that differentiate a sand dune ecotype of the prairie sunflower (Helianthus petiolaris) from populations found on the adjacent sand sheet. We detected seven large genomic regions that exhibit a different population structure than the rest of the genome and that vary in frequency between dune and nondune populations. These regions also show high linkage disequilibrium and high heterozygosity between, but not within, arrangements, consistent with the behaviour of large inversions, an inference subsequently validated in part by comparative genetic mapping. Genome-environment association analyses show that key environmental variables, including vegetation cover and soil nitrogen, are significantly associated with inversions. The inversions colocate with previously described "islands of differentiation," and appear to play an important role in adaptive divergence and incipient speciation within H. petiolaris.
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Affiliation(s)
- Kaichi Huang
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Rose L Andrew
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Gregory L Owens
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Kate L Ostevik
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Biology, Duke University, Durham, NC, USA
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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23
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Ríos N, Casanova A, Hermida M, Pardo BG, Martínez P, Bouza C, García G. Population Genomics in Rhamdia quelen (Heptapteridae, Siluriformes) Reveals Deep Divergence and Adaptation in the Neotropical Region. Genes (Basel) 2020; 11:genes11010109. [PMID: 31963477 PMCID: PMC7017130 DOI: 10.3390/genes11010109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/10/2020] [Accepted: 01/14/2020] [Indexed: 12/16/2022] Open
Abstract
Rhamdia quelen, a Neotropical fish with hybridization between highly divergent mitochondrial DNA (mtDNA) lineages, represents an interesting evolutionary model. Previous studies suggested that there might be demographic differences between coastal lagoons and riverine environments, as well as divergent populations that could be reproductively isolated. Here, we investigated the genetic diversity pattern of this taxon in the Southern Neotropical Basin system that includes the La Plata Basin, Patos-Merin lagoon basin and the coastal lagoons draining to the SW Atlantic Ocean, through a population genomics approach using 2b-RAD-sequencing-derived single nucleotide polymorphisms (SNPs). The genomic scan identified selection footprints associated with divergence and suggested local adaptation environmental drivers. Two major genomic clusters latitudinally distributed in the Northern and Southern basins were identified, along with consistent signatures of divergent selection between them. Population structure based on the whole set of loci and on the presumptive neutral vs. adaptive loci showed deep genomic divergence between the two major clusters. Annotation of the most consistent SNPs under divergent selection revealed some interesting candidate genes for further functional studies. Moreover, signals of adaptation to a coastal lagoon environment mediated by purifying selection were found. These new insights provide a better understanding of the complex evolutionary history of R. quelen in the southernmost basin of the Neotropical region.
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Affiliation(s)
- Néstor Ríos
- Sección Genética Evolutiva, Facultad de Ciencias, UdelaR, Iguá 4225, Montevideo 11400, Uruguay;
- Correspondence: ; Tel.: +598-25258618 (ext. 140)
| | - Adrián Casanova
- Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain; (A.C.); (M.H.); (B.G.P.); (P.M.); (C.B.)
| | - Miguel Hermida
- Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain; (A.C.); (M.H.); (B.G.P.); (P.M.); (C.B.)
| | - Belén G. Pardo
- Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain; (A.C.); (M.H.); (B.G.P.); (P.M.); (C.B.)
- Instituto de Acuicultura, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - Paulino Martínez
- Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain; (A.C.); (M.H.); (B.G.P.); (P.M.); (C.B.)
- Instituto de Acuicultura, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - Carmen Bouza
- Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain; (A.C.); (M.H.); (B.G.P.); (P.M.); (C.B.)
- Instituto de Acuicultura, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela, Spain
| | - Graciela García
- Sección Genética Evolutiva, Facultad de Ciencias, UdelaR, Iguá 4225, Montevideo 11400, Uruguay;
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24
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Murray KD, Janes JK, Jones A, Bothwell HM, Andrew RL, Borevitz JO. Landscape drivers of genomic diversity and divergence in woodland Eucalyptus. Mol Ecol 2019; 28:5232-5247. [PMID: 31647597 PMCID: PMC7065176 DOI: 10.1111/mec.15287] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 10/23/2019] [Indexed: 01/03/2023]
Abstract
Spatial genetic patterns are influenced by numerous factors, and they can vary even among coexisting, closely related species due to differences in dispersal and selection. Eucalyptus (L'Héritier 1789; the "eucalypts") are foundation tree species that provide essential habitat and modulate ecosystem services throughout Australia. Here we present a study of landscape genomic variation in two woodland eucalypt species, using whole-genome sequencing of 388 individuals of Eucalyptus albens and Eucalyptus sideroxylon. We found exceptionally high genetic diversity (π ≈ 0.05) and low genome-wide, interspecific differentiation (FST = 0.15) and intraspecific differentiation between localities (FST ≈ 0.01-0.02). We found no support for strong, discrete population structure, but found substantial support for isolation by geographic distance (IBD) in both species. Using generalized dissimilarity modelling, we identified additional isolation by environment (IBE). Eucalyptus albens showed moderate IBD, and environmental variables have a small but significant amount of additional predictive power (i.e. IBE). Eucalyptus sideroxylon showed much stronger IBD and moderate IBE. These results highlight the vast adaptive potential of these species and set the stage for testing evolutionary hypotheses of interspecific adaptive differentiation across environments.
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Affiliation(s)
| | - Jasmine K Janes
- University of New EnglandArmidaleNSWAustralia
- Vancouver Island University,NanaimoBCCanada
| | - Ashley Jones
- Australian National UniversityCanberraACTAustralia
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25
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Guðbrandsson J, Kapralova KH, Franzdóttir SR, Bergsveinsdóttir ÞM, Hafstað V, Jónsson ZO, Snorrason SS, Pálsson A. Extensive genetic differentiation between recently evolved sympatric Arctic charr morphs. Ecol Evol 2019; 9:10964-10983. [PMID: 31641448 PMCID: PMC6802010 DOI: 10.1002/ece3.5516] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 12/22/2022] Open
Abstract
The availability of diverse ecological niches can promote adaptation of trophic specializations and related traits, as has been repeatedly observed in evolutionary radiations of freshwater fish. The role of genetics, environment, and history in ecologically driven divergence and adaptation, can be studied on adaptive radiations or populations showing ecological polymorphism. Salmonids, especially the Salvelinus genus, are renowned for both phenotypic diversity and polymorphism. Arctic charr (Salvelinus alpinus) invaded Icelandic streams during the glacial retreat (about 10,000 years ago) and exhibits many instances of sympatric polymorphism. Particularly, well studied are the four morphs in Lake Þingvallavatn in Iceland. The small benthic (SB), large benthic (LB), planktivorous (PL), and piscivorous (PI) charr differ in many regards, including size, form, and life history traits. To investigate relatedness and genomic differentiation between morphs, we identified variable sites from RNA-sequencing data from three of those morphs and verified 22 variants in population samples. The data reveal genetic differences between the morphs, with the two benthic morphs being more similar and the PL-charr more genetically different. The markers with high differentiation map to all linkage groups, suggesting ancient and pervasive genetic separation of these three morphs. Furthermore, GO analyses suggest differences in collagen metabolism, odontogenesis, and sensory systems between PL-charr and the benthic morphs. Genotyping in population samples from all four morphs confirms the genetic separation and indicates that the PI-charr are less genetically distinct than the other three morphs. The genetic separation of the other three morphs indicates certain degree of reproductive isolation. The extent of gene flow between the morphs and the nature of reproductive barriers between them remain to be elucidated.
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Affiliation(s)
- Jóhannes Guðbrandsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Marine and Freshwater Research InstituteReykjavikIceland
| | - Kalina H. Kapralova
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
| | - Sigríður R. Franzdóttir
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
| | | | - Völundur Hafstað
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
| | - Zophonías O. Jónsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
| | | | - Arnar Pálsson
- Institute of Life and Environmental SciencesUniversity of IcelandReykjavikIceland
- Biomedical CenterUniversity of IcelandReykjavikIceland
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26
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Zhang JQ, Imerovski I, Borkowski K, Huang K, Burge D, Rieseberg LH. Intraspecific genetic divergence within Helianthus niveus and the status of two new morphotypes from Mexico. AMERICAN JOURNAL OF BOTANY 2019; 106:1229-1239. [PMID: 31461165 DOI: 10.1002/ajb2.1349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/17/2019] [Indexed: 05/12/2023]
Abstract
PREMISE Collecting and characterizing the genetic diversity of wild relatives of crops can contribute importantly to sustainable crop production and food security. Wild sunflower, Helianthus niveus, occurs in arid regions in western North America and is partially cross-compatible with the cultivated sunflower (H. annuus). We assessed phylogenetic relationships and patterns of genetic divergence among three previously described subspecies (subsp. niveus, subsp. canescens, and subsp. tephrodes) as well as two new morphotypes of H. niveus recently discovered in extreme drought and dune habitats in Baja California, Mexico. METHODS We measured 50 plants growing in a common garden for 27 morphological traits and conducted principal component analysis to assess patterns of phenotypic variation. Genome size of each accession was determined using flow cytometry. Pollen viability of first generation hybrids between taxa was tested to infer the strength of intrinsic postzygotic reproductive barriers. Finally, genotyping-by-sequencing data were used to investigate the genetic structure and phylogenetic relationships among the previously described subspecies and new morphotypes. RESULTS The intraspecific genetic and phenotypic divergence of H. niveus populations closely tracks their geographical distribution. Subspecies niveus is phenotypically, genetically, and reproductively distinct from the other two subspecies and has a larger genome. Therefore, H. niveus as currently circumscribed should be considered to contain two distinct species, H. niveus and H. tephrodes. ABBA-BABA tests revealed substantial introgression between subsp. canescens and its sympatric congener H. petiolaris, which might contribute to their morphological similarities. The two new morphotypes collected in Mexico represent local ecotypes of subsp. niveus that occur in extreme drought and dune environments. Mantel tests showed a strong positive correlation between genetic and geographic distances. CONCLUSIONS We conclude that geographic isolation is primarily responsible for intraspecific genomic divergence within H. niveus, while patterns of phenotypic variation appear to have been shaped by ecological selection and interspecific introgression.
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Affiliation(s)
- Jian-Qiang Zhang
- College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
| | - Ivana Imerovski
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
| | - Kelly Borkowski
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
| | - Kaichi Huang
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
| | - Dylan Burge
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T1Z4, Canada
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27
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Aguirre-Liguori JA, Gaut BS, Jaramillo-Correa JP, Tenaillon MI, Montes-Hernández S, García-Oliva F, Hearne SJ, Eguiarte LE. Divergence with gene flow is driven by local adaptation to temperature and soil phosphorus concentration in teosinte subspecies (Zea mays parviglumis and Zea mays mexicana). Mol Ecol 2019; 28:2814-2830. [PMID: 30980686 DOI: 10.1111/mec.15098] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 03/27/2019] [Accepted: 04/08/2019] [Indexed: 01/03/2023]
Abstract
Patterns of genomic divergence between hybridizing taxa can be heterogeneous along the genome. Both differential introgression and local adaptation may contribute to this pattern. Here, we analysed two teosinte subspecies, Zea mays ssp. parviglumis and ssp. mexicana, to test whether their divergence has occurred in the face of gene flow and to infer which environmental variables have been important drivers of their ecological differentiation. We generated 9,780 DArTseqTM SNPs for 47 populations, and used an additional data set containing 33,454 MaizeSNP50 SNPs for 49 populations. With these data, we inferred features of demographic history and performed genome wide scans to determine the number of outlier SNPs associated with climate and soil variables. The two data sets indicate that divergence has occurred or been maintained despite continuous gene flow and/or secondary contact. Most of the significant SNP associations were to temperature and to phosphorus concentration in the soil. A large proportion of these candidate SNPs were located in regions of high differentiation that had been identified previously as putative inversions. We therefore propose that genomic differentiation in teosintes has occurred by a process of adaptive divergence, with putative inversions contributing to reduced gene flow between locally adapted populations.
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Affiliation(s)
- Jonás A Aguirre-Liguori
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California
| | - Juan Pablo Jaramillo-Correa
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Maud I Tenaillon
- Génétique Quantitative et Evolution- Le Moulon, INRA, Gif-sur-Yvette, France
| | - Salvador Montes-Hernández
- Campo Experimental Bajío, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Celaya, México
| | - Felipe García-Oliva
- Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, México
| | - Sarah J Hearne
- International Maize and Wheat Improvement Center (CIMMYT), Texcoco, México
| | - Luis E Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
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28
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Lavretsky P, DaCosta JM, Sorenson MD, McCracken KG, Peters JL. ddRAD‐seq data reveal significant genome‐wide population structure and divergent genomic regions that distinguish the mallard and close relatives in North America. Mol Ecol 2019; 28:2594-2609. [DOI: 10.1111/mec.15091] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 03/05/2019] [Accepted: 03/29/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Philip Lavretsky
- Department of Biological Sciences University of Texas at El Paso El Paso Texas
- Department of Biological Sciences Wright State University Dayton Ohio
- Department of Biology University of Miami Miami Florida
| | - Jeffrey M. DaCosta
- Biology Department Boston College Chestnut Hill Massachusetts
- Biology Department Boston College Boston Massachusetts
| | | | - Kevin G. McCracken
- Department of Biology University of Miami Miami Florida
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences University of Miami Miami Florida
- Human Genetics and Genomics Hussman Institute for Human Genomics, University of Miami Miller School of Medicine Miami Florida
- Institute of Arctic Biology and University of Alaska Museum University of Alaska Fairbanks Fairbanks Alaska
| | - Jeffrey L. Peters
- Department of Biological Sciences Wright State University Dayton Ohio
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29
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González Marín A, Olave M, Avila LJ, Sites JW, Morando M. Evidence of body size and shape stasis driven by selection in Patagonian lizards of the Phymaturus patagonicus clade (Squamata: Liolaemini). Mol Phylogenet Evol 2018; 129:226-241. [DOI: 10.1016/j.ympev.2018.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/22/2022]
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30
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Wachowiak W, Zaborowska J, Łabiszak B, Perry A, Zucca GM, González-Martínez SC, Cavers S. Molecular signatures of divergence and selection in closely related pine taxa. TREE GENETICS & GENOMES 2018; 14:83. [PMID: 30930708 PMCID: PMC6404648 DOI: 10.1007/s11295-018-1296-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 10/01/2018] [Accepted: 10/10/2018] [Indexed: 06/09/2023]
Abstract
Efforts to detect loci under selection in plants have mostly focussed on single species. However, assuming that intraspecific divergence may lead to speciation, comparisons of genetic variation within and among recently diverged taxa can help to locate such genes. In this study, coalescent and outlier detection methods were used to assess nucleotide polymorphism and divergence at 79 nuclear gene fragments (1212 SNPs) in 16 populations (153 individuals) of the closely related, but phenotypically and ecologically distinct, pine taxa Pinus mugo, P. uliginosa and P. uncinata across their European distributions. Simultaneously, mitochondrial DNA markers, which are maternally inherited in pines and distributed by seeds at short geographic distance, were used to assess genetic relationships of the focal populations and taxa. The majority of nuclear loci showed homogenous patterns of variation between the taxa due to a high number of shared SNPs and haplotypes, similar levels of polymorphism, and low net divergence. However, against this common genetic background and an overall low population structure within taxa at mitochondrial markers, we identified several genes showing signatures of selection, accompanied by significant intra- and interspecific divergence. Our results indicate that loci involved in species divergence may be involved in intraspecific local adaptation.
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Affiliation(s)
- Witold Wachowiak
- Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB UK
- Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland
- Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Julia Zaborowska
- Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Bartosz Łabiszak
- Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Annika Perry
- Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB UK
| | - Giovanni M. Zucca
- Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB UK
| | | | - Stephen Cavers
- Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB UK
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Menon M, Bagley JC, Friedline CJ, Whipple AV, Schoettle AW, Leal‐Sàenz A, Wehenkel C, Molina‐Freaner F, Flores‐Rentería L, Gonzalez‐Elizondo MS, Sniezko RA, Cushman SA, Waring KM, Eckert AJ. The role of hybridization during ecological divergence of southwestern white pine (
Pinus strobiformis
) and limber pine (
P. flexilis
). Mol Ecol 2018; 27:1245-1260. [DOI: 10.1111/mec.14505] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Mitra Menon
- Integrative Life Sciences Virginia Commonwealth University Richmond VA USA
- Department of Biology Virginia Commonwealth University Richmond VA USA
| | - Justin C. Bagley
- Department of Biology Virginia Commonwealth University Richmond VA USA
- Departamento de Zoologia Universidade de Brasília Brasília DF Brazil
| | | | - Amy V. Whipple
- Department of Biological Sciences and Merriam Powel Center for Environmental Research Northern Arizona University Flagstaff AZ USA
| | - Anna W. Schoettle
- Rocky Mountain Research Station USDA Forest Service Ft. Collins CO USA
| | - Alejandro Leal‐Sàenz
- Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales Universidad Juárez del Estado de Durango Durango Mexico
| | - Christian Wehenkel
- Instituto de Silvicultura e Industria de la Madera Universidad Juarez del Estado de Durango Durango Mexico
| | - Francisco Molina‐Freaner
- Institutos de Geologia y Ecologia Universidad Nacional Autónoma de Mexico, Estación Regional del Noroeste Hermosillo Sonora Mexico
| | | | | | | | - Samuel A. Cushman
- Rocky Mountain Research Station USDA Forest Service Flagstaff AZ USA
| | | | - Andrew J. Eckert
- Department of Biology Virginia Commonwealth University Richmond VA USA
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32
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Nadeau NJ, Kawakami T. Population Genomics of Speciation and Admixture. POPULATION GENOMICS 2018. [DOI: 10.1007/13836_2018_24] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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33
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Eberlein C, Nielly-Thibault L, Maaroufi H, Dubé AK, Leducq JB, Charron G, Landry CR. The Rapid Evolution of an Ohnolog Contributes to the Ecological Specialization of Incipient Yeast Species. Mol Biol Evol 2017; 34:2173-2186. [PMID: 28482005 DOI: 10.1093/molbev/msx153] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Identifying the molecular changes that lead to ecological specialization during speciation is one of the major goals of molecular evolution. One question that remains to be thoroughly investigated is whether ecological specialization derives strictly from adaptive changes and their associated trade-offs, or from conditionally neutral mutations that accumulate under relaxed selection. We used whole-genome sequencing, genome annotation and computational analyses to identify genes that have rapidly diverged between two incipient species of Saccharomyces paradoxus that occupy different climatic regions along a south-west to north-east gradient. As candidate loci for ecological specialization, we identified genes that show signatures of adaptation and accelerated rates of amino acid substitutions, causing asymmetric evolution between lineages. This set of genes includes a glycyl-tRNA-synthetase, GRS2, which is known to be transcriptionally induced under heat stress in the model and sister species S. cerevisiae. Molecular modelling, expression analysis and fitness assays suggest that the accelerated evolution of this gene in the Northern lineage may be caused by relaxed selection. GRS2 arose during the whole-genome duplication (WGD) that occurred 100 million years ago in the yeast lineage. While its ohnolog GRS1 has been preserved in all post-WGD species, GRS2 has frequently been lost and is evolving rapidly, suggesting that the fate of this ohnolog is still to be resolved. Our results suggest that the asymmetric evolution of GRS2 between the two incipient S. paradoxus species contributes to their restricted climatic distributions and thus that ecological specialization derives at least partly from relaxed selection rather than a molecular trade-off resulting from adaptive evolution.
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Affiliation(s)
- Chris Eberlein
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Lou Nielly-Thibault
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada.,Big Data Research Center (CRDM), Université Laval, Québec, QC, Canada
| | - Halim Maaroufi
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Alexandre K Dubé
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Jean-Baptiste Leducq
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Guillaume Charron
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Christian R Landry
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada.,Big Data Research Center (CRDM), Université Laval, Québec, QC, Canada
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34
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Kamdem C, Fouet C, White BJ. Chromosome arm-specific patterns of polymorphism associated with chromosomal inversions in the major African malaria vector, Anopheles funestus. Mol Ecol 2017; 26:5552-5566. [PMID: 28833796 PMCID: PMC5927613 DOI: 10.1111/mec.14335] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 08/08/2017] [Accepted: 08/14/2017] [Indexed: 02/02/2023]
Abstract
Chromosomal inversions facilitate local adaptation of beneficial mutations and modulate genetic polymorphism, but the extent of their effects within the genome is still insufficiently understood. The genome of Anopheles funestus, a malaria mosquito endemic to sub-Saharan Africa, contains an impressive number of paracentric polymorphic inversions, which are unevenly distributed among chromosomes and provide an excellent framework for investigating the genomic impacts of chromosomal rearrangements. Here, we present results of a fine-scale analysis of genetic variation within the genome of two weakly differentiated populations of Anopheles funestus inhabiting contrasting moisture conditions in Cameroon. Using population genomic analyses, we found that genetic divergence between the two populations is centred on regions of the genome corresponding to three inversions, which are characterized by high values of FST , absolute sequence divergence and fixed differences. Importantly, in contrast to the 2L chromosome arm, which is collinear, nucleotide diversity is significantly reduced along the entire length of three autosome arms bearing multiple overlapping chromosomal rearrangements. These findings support the idea that interactions between reduced recombination and natural selection within inversions contribute to sculpt nucleotide polymorphism across chromosomes in An. funestus.
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Affiliation(s)
- Colince Kamdem
- Department of Entomology, University of California, Riverside, CA 92521
| | - Caroline Fouet
- Department of Entomology, University of California, Riverside, CA 92521
| | - Bradley J. White
- Department of Entomology, University of California, Riverside, CA 92521
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35
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Southcott L, Kronforst MR. A neutral view of the evolving genomic architecture of speciation. Ecol Evol 2017; 7:6358-6366. [PMID: 28861239 PMCID: PMC5574762 DOI: 10.1002/ece3.3190] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/18/2017] [Accepted: 05/21/2017] [Indexed: 11/18/2022] Open
Abstract
Analyses of genomewide polymorphism data have begun to shed light on speciation and adaptation. Genome scans to identify regions of the genome that are unusually different between populations or species, possibly due to divergent natural or sexual selection, are widespread in speciation genomics. Theoretical and empirical work suggests that such outlier regions may grow faster than linearly during speciation with gene flow due to a rapid transition between low and high reproductive isolation. We investigate whether this pattern could be attributed to neutral processes by simulating genomes under neutral evolution with varying amounts and timing of gene flow. Under both neutral evolution and divergent selection, simulations with little or no gene flow, or with a long allopatric period after its cessation, resulted in faster than linear growth of the proportion of the genome lying in outlier regions. Without selection, higher recent gene flow erased differentiation; with divergent selection, these same scenarios produced nonlinear growth to a plateau. Our results suggest that, given a history of gene flow, the growth of the divergent genome is informative about selection during divergence, but that in many scenarios, this pattern does not easily distinguish neutral and non-neutral processes during speciation with gene flow.
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Affiliation(s)
- Laura Southcott
- Committee on Evolutionary BiologyUniversity of ChicagoChicagoILUSA
| | - Marcus R. Kronforst
- Committee on Evolutionary BiologyUniversity of ChicagoChicagoILUSA
- Department of Ecology and EvolutionUniversity of ChicagoChicagoILUSA
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36
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RADseq provides evidence for parallel ecotypic divergence in the autotetraploid Cochlearia officinalis in Northern Norway. Sci Rep 2017; 7:5573. [PMID: 28717144 PMCID: PMC5514025 DOI: 10.1038/s41598-017-05794-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 06/02/2017] [Indexed: 11/08/2022] Open
Abstract
Speciation encompasses a continuum over time from freely interbreeding populations to reproductively isolated species. Along this process, ecotypes - the result of local adaptation - may be on the road to new species. We investigated whether three autotetraploid Cochlearia officinalis ecotypes, adapted to different habitats (beach, estuary, spring), are genetically differentiated and result from parallel ecotypic divergence in two distinct geographical regions. We obtained genetic data from thousands of single nucleotide polymorphisms (SNPs) from restriction-site associated DNA sequencing (RADseq) and from six microsatellite markers for 12 populations to assess genetic divergence at ecotypic, geographic and population level. The genetic patterns support differentiation among ecotypes as suggested by morphology and ecology. The data fit a scenario where the ancestral beach ecotype has recurrently and polytopically given rise to the estuary and spring ecotypes. Several ecologically-relevant loci with consistent non-random segregating patterns are identified across the recurrent origins, in particular around genes related to salt stress. Despite being ecologically distinct, the Cochlearia ecotypes still represent an early stage in the process of speciation, as reproductive isolation has not (yet) developed. A sequenced annotated genome is needed to specifically target candidate genes underlying local adaptation.
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37
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Kamdem C, Fouet C, Gamez S, White BJ. Pollutants and Insecticides Drive Local Adaptation in African Malaria Mosquitoes. Mol Biol Evol 2017; 34:1261-1275. [PMID: 28204524 PMCID: PMC5400387 DOI: 10.1093/molbev/msx087] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Anopheles gambiae complex contains a number of highly anthropophilic mosquito species that have acquired exceptional ability to thrive in complex human habitats. Thus, examining the evolutionary history of this Afrotropical mosquito may yield vital information on the selective processes that occurred during the adaptation to human-dominated environments. We performed reduced representation sequencing on 941 mosquitoes of the Anopheles gambiae complex collected across four ecogeographic zones in Cameroon. We find evidence for genetic and geographic subdivision within An. coluzzii and An. gambiae sensu stricto-the two most significant malaria vectors in the region. Importantly, in both species, rural and urban populations are genetically differentiated. Genome scans reveal pervasive signatures of selection centered on genes involved in xenobiotic resistance. Notably, a selective sweep containing detoxification enzymes is prominent in urban mosquitoes that exploit polluted breeding sites. Overall, our study suggests that recent anthropogenic environmental modifications and widespread use of insecticides are driving population differentiation and local adaptation in vectors with potentially significant consequences for malaria epidemiology.
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Affiliation(s)
- Colince Kamdem
- Department of Entomology, University of California, Riverside, CA
| | - Caroline Fouet
- Department of Entomology, University of California, Riverside, CA
| | - Stephanie Gamez
- Department of Entomology, University of California, Riverside, CA
| | - Bradley J. White
- Department of Entomology, University of California, Riverside, CA
- Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA
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38
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Stacy EA, Paritosh B, Johnson MA, Price DK. Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers. Ecol Evol 2017; 7:2501-2512. [PMID: 28428842 PMCID: PMC5395442 DOI: 10.1002/ece3.2867] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/06/2017] [Accepted: 02/06/2017] [Indexed: 01/18/2023] Open
Abstract
Whereas disruptive selection imposed by heterogeneous environments can lead to the evolution of extrinsic isolating barriers between diverging populations, the evolution of intrinsic postzygotic barriers through divergent selection is less certain. Long-lived species such as trees may be especially slow to evolve intrinsic isolating barriers. We examined postpollination reproductive isolating barriers below the species boundary, in an ephemeral hybrid zone between two successional varieties of the landscape-dominant Hawaiian tree, Metrosideros polymorpha, on volcanically active Hawai'i Island. These archipelago-wide sympatric varieties show the weakest neutral genetic divergence of any taxon pair on Hawai'i Island but significant morphological and ecological differentiation consistent with adaptation to new and old lava flows. Cross-fertility between varieties was high and included heterosis of F1 hybrids at the seed germination stage, consistent with a substantial genetic load apparent within varieties through low self-fertility and a lack of self-pollen discrimination. However, a partial, but significant, barrier was observed in the form of reduced female and male fertility of hybrids, especially backcross hybrids, consistent with the accumulation of genetic incompatibilities between varieties. These results suggest that partial intrinsic postzygotic barriers can arise through disruptive selection acting on large, hybridizing populations of a long-lived species.
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Affiliation(s)
- Elizabeth A. Stacy
- Department of BiologyUniversity of Hawai'i HiloHiloHIUSA
- Tropical Conservation Biology and Environmental Science Graduate ProgramUniversity of Hawai'i HiloHiloHIUSA
- Present address: School of Life SciencesUniversity of Nevada, Las Vegas4505 S Maryland PkwyLas VegasNV89154USA
| | - Bhama Paritosh
- Department of BiologyUniversity of Hawai'i HiloHiloHIUSA
| | - Melissa A. Johnson
- Tropical Conservation Biology and Environmental Science Graduate ProgramUniversity of Hawai'i HiloHiloHIUSA
- Present address: Department of BotanyClaremont Graduate University, Rancho Santa Ana Botanic Garden1500 N. College Ave.ClaremontCA91711USA
| | - Donald K. Price
- Department of BiologyUniversity of Hawai'i HiloHiloHIUSA
- Tropical Conservation Biology and Environmental Science Graduate ProgramUniversity of Hawai'i HiloHiloHIUSA
- Present address: School of Life SciencesUniversity of Nevada, Las Vegas4505 S Maryland PkwyLas VegasNV89154USA
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39
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Kozak GM, Wadsworth CB, Kahne SC, Bogdanowicz SM, Harrison RG, Coates BS, Dopman EB. A combination of sexual and ecological divergence contributes to rearrangement spread during initial stages of speciation. Mol Ecol 2017. [DOI: 10.111/mwc.1403610.1111/mec.14036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Genevieve M. Kozak
- Department of Biology Tufts University 200 Boston Ave. Ste. 4700 Medford MA 02155 USA
| | - Crista B. Wadsworth
- Department of Biology Tufts University 200 Boston Ave. Ste. 4700 Medford MA 02155 USA
- Harvard TH Chan School of Public Health 677 Huntington Ave. Boston MA 02115 USA
| | - Shoshanna C. Kahne
- Department of Biology Tufts University 200 Boston Ave. Ste. 4700 Medford MA 02155 USA
| | - Steven M. Bogdanowicz
- Department of Ecology and Evolutionary Biology Cornell University 215 Tower Road Ithaca NY 14853 USA
| | - Richard G. Harrison
- Department of Ecology and Evolutionary Biology Cornell University 215 Tower Road Ithaca NY 14853 USA
| | - Brad S. Coates
- Corn Insects and Crop Genetics Research Unit USDA‐ARS Iowa State University 103 Genetics Laboratory Ames IA 50011 USA
| | - Erik B. Dopman
- Department of Biology Tufts University 200 Boston Ave. Ste. 4700 Medford MA 02155 USA
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40
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Kozak GM, Wadsworth CB, Kahne SC, Bogdanowicz SM, Harrison RG, Coates BS, Dopman EB. A combination of sexual and ecological divergence contributes to rearrangement spread during initial stages of speciation. Mol Ecol 2017; 26:2331-2347. [PMID: 28141898 DOI: 10.1111/mec.14036] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 12/12/2016] [Accepted: 01/10/2017] [Indexed: 01/04/2023]
Abstract
Chromosomal rearrangements between sympatric species often contain multiple loci contributing to assortative mating, local adaptation and hybrid sterility. When and how these associations arise during the process of speciation remains a subject of debate. Here, we address the relative roles of local adaptation and assortative mating on the dynamics of rearrangement evolution by studying how a rearrangement covaries with sexual and ecological trait divergence within a species. Previously, a chromosomal rearrangement that suppresses recombination on the Z (sex) chromosome was identified in European corn borer moths (Ostrinia nubilalis). We further characterize this recombination suppressor and explore its association with variation in sex pheromone communication and seasonal ecological adaptation in pairs of populations that are divergent in one or both of these characteristics. Direct estimates of recombination suppression in pedigree mapping families indicated that more than 39% of the Z chromosome (encompassing up to ~10 megabases and ~300 genes) resides within a nonrecombining unit, including pheromone olfactory receptor genes and a major quantitative trait locus that contributes to ecotype differences (Pdd). Combining direct and indirect estimates of recombination suppression, we found that the rearrangement was occasionally present between sexually isolated strains (E vs. Z) and between divergent ecotypes (univoltine vs. bivoltine). However, it was only consistently present when populations differed in both sexual and ecological traits. Our results suggest that independent of the forces that drove the initial establishment of the rearrangement, a combination of sexual and ecological divergence is required for rearrangement spread during speciation.
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Affiliation(s)
- Genevieve M Kozak
- Department of Biology, Tufts University, 200 Boston Ave. Ste. 4700, Medford, MA, 02155, USA
| | - Crista B Wadsworth
- Department of Biology, Tufts University, 200 Boston Ave. Ste. 4700, Medford, MA, 02155, USA.,Harvard TH Chan School of Public Health, 677 Huntington Ave., Boston, MA, 02115, USA
| | - Shoshanna C Kahne
- Department of Biology, Tufts University, 200 Boston Ave. Ste. 4700, Medford, MA, 02155, USA
| | - Steven M Bogdanowicz
- Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Road, Ithaca, NY, 14853, USA
| | - Richard G Harrison
- Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Road, Ithaca, NY, 14853, USA
| | - Brad S Coates
- Corn Insects and Crop Genetics Research Unit, USDA-ARS, Iowa State University, 103 Genetics Laboratory, Ames, IA, 50011, USA
| | - Erik B Dopman
- Department of Biology, Tufts University, 200 Boston Ave. Ste. 4700, Medford, MA, 02155, USA
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41
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McKinney GJ, Larson WA, Seeb LW, Seeb JE. RADseq provides unprecedented insights into molecular ecology and evolutionary genetics: comment on Breaking RAD by Lowry et al
. (2016). Mol Ecol Resour 2017; 17:356-361. [DOI: 10.1111/1755-0998.12649] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/20/2016] [Accepted: 12/20/2016] [Indexed: 01/26/2023]
Affiliation(s)
- Garrett J. McKinney
- School of Aquatic and Fishery Sciences; University of Washington; 1122 NE Boat Street, Box 355020 Seattle WA 98195-5020 USA
| | - Wesley A. Larson
- U.S. Geological Survey; Wisconsin Cooperative Fishery Research Unit; College of Natural Resources; University of Wisconsin-Stevens Point; 800 Reserve St. Stevens Point WI 54481 USA
| | - Lisa W. Seeb
- School of Aquatic and Fishery Sciences; University of Washington; 1122 NE Boat Street, Box 355020 Seattle WA 98195-5020 USA
| | - James E. Seeb
- School of Aquatic and Fishery Sciences; University of Washington; 1122 NE Boat Street, Box 355020 Seattle WA 98195-5020 USA
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42
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Larson WA, Limborg MT, McKinney GJ, Schindler DE, Seeb JE, Seeb LW. Genomic islands of divergence linked to ecotypic variation in sockeye salmon. Mol Ecol 2016; 26:554-570. [PMID: 27864910 DOI: 10.1111/mec.13933] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 10/14/2016] [Accepted: 10/25/2016] [Indexed: 12/14/2022]
Abstract
Regions of the genome displaying elevated differentiation (genomic islands of divergence) are thought to play an important role in local adaptation, especially in populations experiencing high gene flow. However, the characteristics of these islands as well as the functional significance of genes located within them remain largely unknown. Here, we used data from thousands of SNPs aligned to a linkage map to investigate genomic islands of divergence in three ecotypes of sockeye salmon (Oncorhynchus nerka) from a single drainage in southwestern Alaska. We found ten islands displaying high differentiation among ecotypes. Conversely, neutral structure observed throughout the rest of the genome was low and not partitioned by ecotype. One island on linkage group So13 was particularly large and contained six SNPs with FST > 0.14 (average FST of neutral SNPs = 0.01). Functional annotation revealed that the peak of this island contained a nonsynonymous mutation in a gene involved in growth in other species (TULP4). The islands that we discovered were relatively small (80-402 Kb), loci found in islands did not show reduced levels of diversity, and loci in islands displayed slightly elevated linkage disequilibrium. These attributes suggest that the islands discovered here were likely generated by divergence hitchhiking; however, we cannot rule out the possibility that other mechanisms may have produced them. Our results suggest that islands of divergence serve an important role in local adaptation with gene flow and represent a significant advance towards understanding the genetic basis of ecotypic differentiation.
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Affiliation(s)
- Wesley A Larson
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
| | - Morten T Limborg
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
| | - Garrett J McKinney
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
| | - Daniel E Schindler
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
| | - James E Seeb
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
| | - Lisa W Seeb
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA, 98195-5020, USA
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43
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High density, genome-wide markers and intra-specific replication yield an unprecedented phylogenetic reconstruction of a globally significant, speciose lineage of Eucalyptus. Mol Phylogenet Evol 2016; 105:63-85. [DOI: 10.1016/j.ympev.2016.08.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/29/2016] [Accepted: 08/12/2016] [Indexed: 01/07/2023]
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44
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45
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Love RR, Steele AM, Coulibaly MB, Traore SF, Emrich SJ, Fontaine MC, Besansky NJ. Chromosomal inversions and ecotypic differentiation in Anopheles gambiae: the perspective from whole-genome sequencing. Mol Ecol 2016; 25:5889-5906. [PMID: 27759895 DOI: 10.1111/mec.13888] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 09/13/2016] [Accepted: 10/03/2016] [Indexed: 12/30/2022]
Abstract
The molecular mechanisms and genetic architecture that facilitate adaptive radiation of lineages remain elusive. Polymorphic chromosomal inversions, due to their recombination-reducing effect, are proposed instruments of ecotypic differentiation. Here, we study an ecologically diversifying lineage of Anopheles gambiae, known as the Bamako chromosomal form based on its unique complement of three chromosomal inversions, to explore the impact of these inversions on ecotypic differentiation. We used pooled and individual genome sequencing of Bamako, typical (non-Bamako) An. gambiae and the sister species Anopheles coluzzii to investigate evolutionary relationships and genomewide patterns of nucleotide diversity and differentiation among lineages. Despite extensive shared polymorphism and limited differentiation from the other taxa, Bamako clusters apart from the other taxa, and forms a maximally supported clade in neighbour-joining trees based on whole-genome data (including inversions) or solely on collinear regions. Nevertheless, FST outlier analysis reveals that the majority of differentiated regions between Bamako and typical An. gambiae are located inside chromosomal inversions, consistent with their role in the ecological isolation of Bamako. Exceptionally differentiated genomic regions were enriched for genes implicated in nervous system development and signalling. Candidate genes associated with a selective sweep unique to Bamako contain substitutions not observed in sympatric samples of the other taxa, and several insecticide resistance gene alleles shared between Bamako and other taxa segregate at sharply different frequencies in these samples. Bamako represents a useful window into the initial stages of ecological and genomic differentiation from sympatric populations in this important group of malaria vectors.
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Affiliation(s)
- R Rebecca Love
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.,Department of Biological Sciences, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA
| | - Aaron M Steele
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.,Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Mamadou B Coulibaly
- Malaria Research and Training Centre, Faculty of Medicine Pharmacy and Dentistry, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sékou F Traore
- Malaria Research and Training Centre, Faculty of Medicine Pharmacy and Dentistry, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Scott J Emrich
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.,Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Michael C Fontaine
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.,Department of Biological Sciences, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA.,Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
| | - Nora J Besansky
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.,Department of Biological Sciences, University of Notre Dame, Galvin Life Sciences Center, Notre Dame, IN, 46556, USA
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46
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Vijay N, Bossu CM, Poelstra JW, Weissensteiner MH, Suh A, Kryukov AP, Wolf JBW. Evolution of heterogeneous genome differentiation across multiple contact zones in a crow species complex. Nat Commun 2016; 7:13195. [PMID: 27796282 PMCID: PMC5095515 DOI: 10.1038/ncomms13195] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 09/09/2016] [Indexed: 12/31/2022] Open
Abstract
Uncovering the genetic basis of species diversification is a central goal in evolutionary biology. Yet, the link between the accumulation of genomic changes during population divergence and the evolutionary forces promoting reproductive isolation is poorly understood. Here, we analysed 124 genomes of crow populations with various degrees of genome-wide differentiation, with parallelism of a sexually selected plumage phenotype, and ongoing hybridization. Overall, heterogeneity in genetic differentiation along the genome was best explained by linked selection exposed on a shared genome architecture. Superimposed on this common background, we identified genomic regions with signatures of selection specific to independent phenotypic contact zones. Candidate pigmentation genes with evidence for divergent selection were only partly shared, suggesting context-dependent selection on a multigenic trait architecture and parallelism by pathway rather than by repeated single-gene effects. This study provides insight into how various forms of selection shape genome-wide patterns of genomic differentiation as populations diverge.
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Affiliation(s)
- Nagarjun Vijay
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden
| | - Christen M Bossu
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden.,Department of Zoology, Population Genetics, Stockholm University, Stockholm SE-106 91, Sweden
| | - Jelmer W Poelstra
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden
| | - Matthias H Weissensteiner
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden
| | - Alexander Suh
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden
| | - Alexey P Kryukov
- Laboratory of Evolutionary Zoology and Genetics, Institute of Biology and Soil Science, Far East Branch Russian Academy of Sciences, Vladivostok 690022, Russia
| | - Jochen B W Wolf
- Department of Evolutionary Biology and Science for Life Laboratories, Uppsala University, Norbyvägen 18D, Uppsala 75236, Sweden.,Division of Evolutionary Biology, Ludwig Maximilian University of Munich, Grosshaderner Street 2, Planegg-Martinsried 82152, Germany
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47
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Ostevik KL, Andrew RL, Otto SP, Rieseberg LH. Multiple reproductive barriers separate recently diverged sunflower ecotypes. Evolution 2016; 70:2322-2335. [PMID: 27479368 DOI: 10.1111/evo.13027] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 06/12/2016] [Accepted: 06/27/2016] [Indexed: 01/17/2023]
Abstract
Measuring reproductive barriers between groups of organisms is an effective way to determine the traits and mechanisms that impede gene flow. However, to understand the ecological and evolutionary factors that drive speciation, it is important to distinguish between the barriers that arise early in the speciation process and those that arise after speciation is largely complete. In this article, we comprehensively test for reproductive isolation between recently diverged (<10,000 years bp) dune and nondune ecotypes of the prairie sunflower, Helianthus petiolaris. We find reproductive barriers acting at multiple stages of hybridization, including premating, postmating-prezygotic, and postzygotic barriers, despite the recent divergence. Barriers include extrinsic selection against immigrants and hybrids, a shift in pollinator assemblage, and postpollination assortative mating. Together, these data suggest that multiple barriers can be important for reducing gene flow in the earliest stages of speciation.
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Affiliation(s)
- Katherine L Ostevik
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Rose L Andrew
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Sarah P Otto
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Biology, Indiana University, Bloomington, Indiana
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48
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Hendrick MF, Finseth FR, Mathiasson ME, Palmer KA, Broder EM, Breigenzer P, Fishman L. The genetics of extreme microgeographic adaptation: an integrated approach identifies a major gene underlying leaf trichome divergence in Yellowstone Mimulus guttatus. Mol Ecol 2016; 25:5647-5662. [PMID: 27393073 DOI: 10.1111/mec.13753] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 06/15/2016] [Accepted: 06/22/2016] [Indexed: 12/30/2022]
Abstract
Microgeographic adaptation provides a particularly interesting context for understanding the genetic basis of phenotypic divergence and may also present unique empirical challenges. In particular, plant adaptation to extreme soil mosaics may generate barriers to gene flow or shifts in mating system that confound simple genomic scans for adaptive loci. Here, we combine three approaches - quantitative trait locus (QTL) mapping of candidate intervals in controlled crosses, population resequencing (PoolSeq) and analyses of wild recombinant individuals - to investigate one trait associated with Mimulus guttatus (yellow monkeyflower) adaptation to geothermal soils in Yellowstone National Park. We mapped a major QTL causing dense leaf trichomes in thermally adapted plants to a <50-kb region of linkage Group 14 (Tr14) previously implicated in trichome divergence between independent M. guttatus populations. A PoolSeq scan of Tr14 region revealed a cluster of six genes, coincident with the inferred QTL peak, with high allele frequency differences sufficient to explain observed phenotypic differentiation. One of these, the R2R3 MYB transcription factor Migut.N02661, is a plausible functional candidate and was also strongly associated (r2 = 0.27) with trichome phenotype in analyses of wild-collected admixed individuals. Although functional analyses will be necessary to definitively link molecular variants in Tr14 with trichome divergence, our analyses are a major step in that direction. They point to a simple, and parallel, genetic basis for one axis of Mimulus guttatus adaptation to an extreme habitat, suggest a broadly conserved genetic basis for trichome variation across flowering plants and pave the way for further investigations of this challenging case of microgeographic incipient speciation.
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Affiliation(s)
- Margaret F Hendrick
- Division of Biological Sciences, University of Montana, 32 Campus Dr., Missoula, MT, 59812, USA.,Department of Earth and Environment, Boston University, 685 Commonwealth Ave., Boston, MA, 02215, USA
| | - Findley R Finseth
- Division of Biological Sciences, University of Montana, 32 Campus Dr., Missoula, MT, 59812, USA
| | - Minna E Mathiasson
- School of Biology and Ecology, University of Maine, 5751 Murray Hall, Orono, ME, 04469, USA
| | - Kristen A Palmer
- Department of Biology, Wheaton College, 26 E. Main St., Norton, MA, 02766, USA
| | - Emma M Broder
- Biology Department, Wesleyan University, 45 Wyllys Ave., Middletown, CT, 06259, USA
| | - Peter Breigenzer
- Division of Biological Sciences, University of Montana, 32 Campus Dr., Missoula, MT, 59812, USA
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, 32 Campus Dr., Missoula, MT, 59812, USA
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49
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Payseur BA, Rieseberg LH. A genomic perspective on hybridization and speciation. Mol Ecol 2016; 25:2337-60. [PMID: 26836441 PMCID: PMC4915564 DOI: 10.1111/mec.13557] [Citation(s) in RCA: 292] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/18/2016] [Accepted: 01/25/2016] [Indexed: 12/13/2022]
Abstract
Hybridization among diverging lineages is common in nature. Genomic data provide a special opportunity to characterize the history of hybridization and the genetic basis of speciation. We review existing methods and empirical studies to identify recent advances in the genomics of hybridization, as well as issues that need to be addressed. Notable progress has been made in the development of methods for detecting hybridization and inferring individual ancestries. However, few approaches reconstruct the magnitude and timing of gene flow, estimate the fitness of hybrids or incorporate knowledge of recombination rate. Empirical studies indicate that the genomic consequences of hybridization are complex, including a highly heterogeneous landscape of differentiation. Inferred characteristics of hybridization differ substantially among species groups. Loci showing unusual patterns - which may contribute to reproductive barriers - are usually scattered throughout the genome, with potential enrichment in sex chromosomes and regions of reduced recombination. We caution against the growing trend of interpreting genomic variation in summary statistics across genomes as evidence of differential gene flow. We argue that converting genomic patterns into useful inferences about hybridization will ultimately require models and methods that directly incorporate key ingredients of speciation, including the dynamic nature of gene flow, selection acting in hybrid populations and recombination rate variation.
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Affiliation(s)
- Bret A. Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Loren H. Rieseberg
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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50
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Filatov DA, Osborne OG, Papadopulos AST. Demographic history of speciation in a Senecio altitudinal hybrid zone on Mt. Etna. Mol Ecol 2016; 25:2467-81. [PMID: 26994342 DOI: 10.1111/mec.13618] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 02/29/2016] [Accepted: 02/29/2016] [Indexed: 01/16/2023]
Abstract
Hybrid zones typically form as a result of species coming into secondary contact, but can also be established in situ as an ecotonal hybrid zone, a situation which has been reported far less frequently. An altitudinal hybrid zone on Mount Etna between two ragwort species (the low elevation Senecio chrysanthemifolius and high elevation S. aethnensis) could potentially represent either of these possibilities. However, a scenario of secondary contact vs. speciation with gene flow has not been explicitly tested. Here, we test these alternatives and demonstrate that the data do not support secondary contact. Furthermore, we report that the previous analyses of speciation history of these species were based on admixed populations, which has led to inflated estimates of ongoing, interspecific gene flow. Our new analyses, based on 'pure' S. aethnensis and S. chrysanthemifolius populations, reveal gene exchange of less than one effective migrant per generation, a level low enough to allow the species to accumulate neutral, genomewide differences. Overall, our results are consistent with a scenario of speciation with gene flow and a divergence time which coincides with the rise of Mt. Etna to altitudes above 2000 m (~150 KY). Further work to quantify the role of adaptation to contrasting environments of high and low altitudes will be needed to support the scenario of recent ecological speciation in this system.
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Affiliation(s)
- Dmitry A Filatov
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Owen G Osborne
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Alexander S T Papadopulos
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.,Royal Botanic Gardens, Kew, Richmond, TW9 3AB, UK
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