1
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Capblancq T, Sękiewicz K, Dering M. Forest genomics in the Caucasus through the lens of its dominant tree species - Fagus orientalis. Mol Ecol 2024; 33:e17475. [PMID: 39021282 DOI: 10.1111/mec.17475] [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: 01/11/2024] [Revised: 05/29/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024]
Abstract
The last glacial period is known to have greatly influenced the demographic history of temperate forest trees, with important range contractions and post-glacial expansions that led to the formation of multiple genetic lineages and secondary contact zones in the Northern Hemisphere. These dynamics have been extensively studied for European and North American species but are still poorly understood in other temperate regions of rich biodiversity such as the Caucasus. Our study helps filling that gap by deciphering the genomic landscapes of F. orientalis across the South Caucasus. The use of genome-wide data confirmed a past demographic history strongly influenced by the Last Glacial Maximum, revealing two disjunct glacial refugia in the Colchis and Hyrcanian regions. The resulting patterns of genetic diversity, load and differentiation are not always concordant across the region, with genetic load pinpointing the location of the glacial refugia more efficiently than genetic diversity alone. The Hyrcanian forests show depleted genetic diversity and substantial isolation, even if long-distance gene flow is still present with the main centre of diversity in the Greater Caucasus. Finally, we characterize a strong heterogeneity of genetic diversity and differentiation along the species chromosomes, with noticeably a first chromosome showing low diversity and weak differentiation.
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Affiliation(s)
- Thibaut Capblancq
- Université Grenoble-Alpes, Université Savoie Mont Blanc, CNRS, Laboratoire d'Écologie Alpine, Grenoble, France
| | | | - Monika Dering
- Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland
- Department of Silviculture, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Poznań, Poland
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2
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Lewis R, Pointer MD, Friend L, Gage MJG, Spurgin LG. Tests of evolutionary and genetic rescue using flour beetles, Tribolium castaneum, experimentally evolved to thermal conditions. Ecol Evol 2024; 14:e11313. [PMID: 38694756 PMCID: PMC11056960 DOI: 10.1002/ece3.11313] [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: 08/29/2023] [Revised: 03/26/2024] [Accepted: 04/03/2024] [Indexed: 05/04/2024] Open
Abstract
Small, isolated populations are often characterised by low levels of genetic diversity. This can result in inbreeding depression and reduced capacity to adapt to changes in the environment, and therefore higher risk of extinction. However, sometimes these populations can be rescued if allowed to increase in size or if migrants enter, bringing in new allelic variation and thus increasing genetic diversity. This study uses experimental manipulation of population size and migration to quantify their effects on fitness in a challenging environment to better understand genetic rescue. Using small, replicated populations of Tribolium castaneum experimentally evolved to different temperature regimes we tested genetic and demographic rescue, by performing large-scale manipulations of population size and migration and examining fitness consequences over multiple generations. We measured fitness in high temperature (38°C) thermal lines maintained at their usual 'small' population size of N = 100 individuals, and with 'large' scaled up duplicates containing N≈10,000 individuals. We compared these large lines with and without migration (m = 0.1) for 10 generations. Additionally, we assessed the effects of outcrossing at an individual level, by comparing fitness of hybrid (thermal line × stock) offspring with within-line crosses. We found that, at the population level, a rapid increase in the number of individuals in the population resulted in reduced fitness (represented by reproductive output and survival through heatwave conditions), regardless of migration. However, at an individual level, the hybrid offspring of migrants with native individuals generally demonstrated increased longevity in high temperature conditions compared with individuals from thermal selection lines. Overall, these populations showed no evidence that demographic manipulations led to genetic or evolutionary rescue. Following the effects of migration in individuals over several generations may be the next step in unravelling these conflicting results. We discuss these findings in the context of conservation intervention.
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Affiliation(s)
- Rebecca Lewis
- School of Biological SciencesUniversity of East AngliaNorwichUK
| | | | - Lucy Friend
- School of Biological SciencesUniversity of East AngliaNorwichUK
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3
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Booker WW, Schrider DR. The genetic consequences of range expansion and its influence on diploidization in polyploids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.18.562992. [PMID: 37905020 PMCID: PMC10614938 DOI: 10.1101/2023.10.18.562992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Despite newly formed polyploids being subjected to myriad fitness consequences, the relative prevalence of polyploidy both contemporarily and in ancestral branches of the tree of life suggests alternative advantages that outweigh these consequences. One proposed advantage is that polyploids may more easily colonize novel habitats such as deglaciated areas. However, previous research conducted in diploids suggests that range expansion comes with a fitness cost as deleterious mutations may fix rapidly on the expansion front. Here, we interrogate the potential consequences of expansion in polyploids by conducting spatially explicit forward-in-time simulations to investigate how ploidy and inheritance patterns impact the relative ability of polyploids to expand their range. We show that under realistic dominance models, autopolyploids suffer greater fitness reductions than diploids as a result of range expansion due to the fixation of increased mutational load that is masked in the range core. Alternatively, the disomic inheritance of allopolyploids provides a shield to this fixation resulting in minimal fitness consequences. In light of this advantage provided by disomy, we investigate how range expansion may influence cytogenetic diploidization through the reversion to disomy in autotetraploids. We show that under a wide range of parameters investigated for two models of diploidization, disomy frequently evolves more rapidly on the expansion front than in the range core, and that this dynamic inheritance model has additional effects on fitness. Together our results point to a complex interaction between dominance, ploidy, inheritance, and recombination on fitness as a population spreads across a geographic range.
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Affiliation(s)
- William W. Booker
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
| | - Daniel R. Schrider
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27514-2916, United States of America
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4
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Jiang J, Xu YC, Zhang ZQ, Chen JF, Niu XM, Hou XH, Li XT, Wang L, Zhang YE, Ge S, Guo YL. Forces driving transposable element load variation during Arabidopsis range expansion. THE PLANT CELL 2024; 36:840-862. [PMID: 38036296 PMCID: PMC10980350 DOI: 10.1093/plcell/koad296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/25/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Genetic load refers to the accumulated and potentially life-threatening deleterious mutations in populations. Understanding the mechanisms underlying genetic load variation of transposable element (TE) insertion, a major large-effect mutation, during range expansion is an intriguing question in biology. Here, we used 1,115 global natural accessions of Arabidopsis (Arabidopsis thaliana) to study the driving forces of TE load variation during its range expansion. TE load increased with range expansion, especially in the recently established Yangtze River basin population. Effective population size, which explains 62.0% of the variance in TE load, high transposition rate, and selective sweeps contributed to TE accumulation in the expanded populations. We genetically mapped and identified multiple candidate causal genes and TEs, and revealed the genetic architecture of TE load variation. Overall, this study reveals the variation in TE genetic load during Arabidopsis expansion and highlights the causes of TE load variation from the perspectives of both population genetics and quantitative genetics.
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Affiliation(s)
- Juan Jiang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong-Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Zhi-Qin Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Fu Chen
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Min Niu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Xing-Hui Hou
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Xin-Tong Li
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Wang
- Agricultural Synthetic Biology Center, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Yong E Zhang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- State Key Laboratory of Integrated Management of Pest Insects and Rodents & Key Laboratory of the Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Song Ge
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ya-Long Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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5
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Urquhart-Cronish M, Angert AL, Otto SP, MacPherson A. Density-Dependent Selection during Range Expansion Affects Expansion Load in Life History Traits. Am Nat 2024; 203:382-392. [PMID: 38358811 DOI: 10.1086/728599] [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] [Indexed: 02/17/2024]
Abstract
AbstractModels of range expansion have independently explored fitness consequences of life history trait evolution and increased rates of genetic drift-or "allele surfing"-during spatial spread, but no previous model has examined the interactions between these two processes. Here, using spatially explicit simulations, we explore an ecologically complex range expansion scenario that combines density-dependent selection with allele surfing to asses the genetic and fitness consequences of density-dependent selection on the evolution of life history traits. We demonstrate that density-dependent selection on the range edge acts differently depending on the life history trait and can either diminish or enhance allele surfing. Specifically, we show that selection at the range edge is always weaker at sites affecting competitive ability (K-selected traits) than at sites affecting birth rate (r-selected traits). We then link differences in the frequency of deleterious mutations to differences in the efficacy of selection and rate of mutation accumulation across distinct life history traits. Finally, we demonstrate that the observed fitness consequences of allele surfing depend on the population density in which expansion load is measured. Our work highlights the complex relationship between ecology and expressed genetic load, which will be important to consider when interpreting both experimental and field studies of range expansion.
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Hall R, Bandara A, Charlebois DA. Fitness effects of a demography-dispersal trade-off in expanding Saccharomyces cerevisiaemats. Phys Biol 2024; 21:026001. [PMID: 38194907 DOI: 10.1088/1478-3975/ad1ccd] [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: 04/12/2023] [Accepted: 01/09/2024] [Indexed: 01/11/2024]
Abstract
Fungi expand in space and time to form complex multicellular communities. The mechanisms by which they do so can vary dramatically and determine the life-history and dispersal traits of expanding populations. These traits influence deterministic and stochastic components of evolution, resulting in complex eco-evolutionary dynamics during colony expansion. We perform experiments on budding yeast strains genetically engineered to display rough-surface and smooth-surface phenotypes in colony-like structures called 'mats'. Previously, it was shown that the rough-surface strain has a competitive advantage over the smooth-surface strain when grown on semi-solid media. We experimentally observe the emergence and expansion of segments with a distinct smooth-surface phenotype during rough-surface mat development. We propose a trade-off between dispersal and local carrying capacity to explain the relative fitness of these two phenotypes. Using a modified stepping-stone model, we demonstrate that this trade-off gives the high-dispersing, rough-surface phenotype a competitive advantage from standing variation, but that it inhibits this phenotype's ability to invade a resident smooth-surface population via mutation. However, the trade-off improves the ability of the smooth-surface phenotype to invade in rough-surface mats, replicating the frequent emergence of smooth-surface segments in experiments. Together, these computational and experimental findings advance our understanding of the complex eco-evolutionary dynamics of fungal mat expansion.
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Affiliation(s)
- Rebekah Hall
- Department of Mathematical and Statistical Sciences, University of Alberta, 11455 Saskatchewan Drive NW, Edmonton, Alberta, Canada
| | - Akila Bandara
- Department of Physics, University of Alberta, 11455 Saskatchewan Drive NW, Edmonton, Alberta, Canada
| | - Daniel A Charlebois
- Department of Physics, University of Alberta, 11455 Saskatchewan Drive NW, Edmonton, Alberta, Canada
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive NW, Edmonton, Alberta, Canada
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7
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Cang FA, Welles SR, Wong J, Ziaee M, Dlugosch KM. Genome size variation and evolution during invasive range expansion in an introduced plant. Evol Appl 2024; 17:e13624. [PMID: 38283607 PMCID: PMC10810172 DOI: 10.1111/eva.13624] [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: 06/01/2023] [Revised: 11/03/2023] [Accepted: 11/13/2023] [Indexed: 01/30/2024] Open
Abstract
Plants demonstrate exceptional variation in genome size across species, and their genome sizes can also vary dramatically across individuals and populations within species. This aspect of genetic variation can have consequences for traits and fitness, but few studies attributed genome size differentiation to ecological and evolutionary processes. Biological invasions present particularly useful natural laboratories to infer selective agents that might drive genome size shifts across environments and population histories. Here, we test hypotheses for the evolutionary causes of genome size variation across 14 invading populations of yellow starthistle, Centaurea solstitialis, in California, United States. We use a survey of genome sizes and trait variation to ask: (1) Is variation in genome size associated with developmental trait variation? (2) Are genome sizes smaller toward the leading edge of the expansion, consistent with selection for "colonizer" traits? Or alternatively, does genome size increase toward the leading edge of the expansion, consistent with predicted consequences of founder effects and drift? (3) Finally, are genome sizes smaller at higher elevations, consistent with selection for shorter development times? We found that 2C DNA content varied 1.21-fold among all samples, and was associated with flowering time variation, such that plants with larger genomes reproduced later, with lower lifetime capitula production. Genome sizes increased toward the leading edge of the invasion, but tended to decrease at higher elevations, consistent with genetic drift during range expansion but potentially strong selection for smaller genomes and faster development time at higher elevations. These results demonstrate how genome size variation can contribute to traits directly tied to reproductive success, and how selection and drift can shape that variation. We highlight the influence of genome size on dynamics underlying a rapid range expansion in a highly problematic invasive plant.
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Affiliation(s)
- F. Alice Cang
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizonaUSA
| | - Shana R. Welles
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizonaUSA
- Utah Valley UniversityOremUtahUSA
| | - Jenny Wong
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizonaUSA
| | - Maia Ziaee
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizonaUSA
- Mills CollegeOaklandCaliforniaUSA
| | - Katrina M. Dlugosch
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonArizonaUSA
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8
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Jones FAM, Bogdanoff C, Wolkovich EM. The role of genotypic and climatic variation at the range edge: A case study in winegrapes. AMERICAN JOURNAL OF BOTANY 2024; 111:e16270. [PMID: 38156528 DOI: 10.1002/ajb2.16270] [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: 02/17/2023] [Revised: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 12/30/2023]
Abstract
PREMISE Changes in habitat suitability due to climate change are causing range shifts, with new habitat potentially available at cold range edges. We must predict these range shifts, but forecasters have limited knowledge of how genetic differences in plant physiological tolerances influence range shifts. Here, we focus on a major determinant of species ranges-physiological tolerance to extreme cold-to ask how warming over recent decades and genetic variation shape expansion across complex landscapes. METHODS We examined how genotypes vary in maximum cold tolerance from 9 years of cold hardiness data across 18 genotypes from 13 sites, using winegrapes (Vitis vinifera subsp. vinifera) as a case study. Combining a Bayesian hierarchical dose-response model with gridded climate data, we then project changes in climatic suitability near winegrapes' current cold range-edge between 1949 and 2016. RESULTS Plants increased maximum cold hardiness non-linearly with decreasing air temperature (maximum cold hardiness: -23.6°C), but with substantial (by 2°C) variation across genotypes. Our results suggest, since the 1980s, decreasing freeze injury risk has made conditions more favorable for all genotypes at the cold range-edge, but conditions remained more favorable for more cold hardy genotypes and in warmer areas. There was substantial spatial variation in habitat suitability, with the majority of suitably warm habitat located in a narrow north-south oriented strip. CONCLUSIONS We highlight the importance of genotypic differences in physiological tolerances when assessing range shift potential with climate change. Habitat improvements were unevenly distributed over the spatially complex landscape, though, emphasizing the importance of dispersal in range expansion.
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Affiliation(s)
- Faith A M Jones
- Department of Forest and Conservation, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Colombia, V6T 1Z4, Canada
- Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden
| | - Carl Bogdanoff
- Agriculture and Agri-Food, Summerland, British Columbia, V0H 1Z0, Canada
| | - E M Wolkovich
- Department of Forest and Conservation, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Colombia, V6T 1Z4, Canada
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9
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Kim AS, Kreiner JM, Hernández F, Bock DG, Hodgins KA, Rieseberg LH. Temporal collections to study invasion biology. Mol Ecol 2023; 32:6729-6742. [PMID: 37873879 DOI: 10.1111/mec.17176] [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: 08/22/2023] [Revised: 10/07/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023]
Abstract
Biological invasions represent an extraordinary opportunity to study evolution. This is because accidental or deliberate species introductions have taken place for centuries across large geographical scales, frequently prompting rapid evolutionary transitions in invasive populations. Until recently, however, the utility of invasions as evolutionary experiments has been hampered by limited information on the makeup of populations that were part of earlier invasion stages. Now, developments in ancient and historical DNA technologies, as well as the quickening pace of digitization for millions of specimens that are housed in herbaria and museums globally, promise to help overcome this obstacle. In this review, we first introduce the types of temporal data that can be used to study invasions, highlighting the timescale captured by each approach and their respective limitations. We then discuss how ancient and historical specimens as well as data available from prior invasion studies can be used to answer questions on mechanisms of (mal)adaptation, rates of evolution, or community-level changes during invasions. By bridging the gap between contemporary and historical invasive populations, temporal data can help us connect pattern to process in invasion science. These data will become increasingly important if invasions are to achieve their full potential as experiments of evolution in nature.
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Affiliation(s)
- Amy S Kim
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Julia M Kreiner
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Fernando Hernández
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dan G Bock
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kathryn A Hodgins
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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10
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Pinsky ML, Clark RD, Bos JT. Coral Reef Population Genomics in an Age of Global Change. Annu Rev Genet 2023; 57:87-115. [PMID: 37384733 DOI: 10.1146/annurev-genet-022123-102748] [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] [Indexed: 07/01/2023]
Abstract
Coral reefs are both exceptionally biodiverse and threatened by climate change and other human activities. Here, we review population genomic processes in coral reef taxa and their importance for understanding responses to global change. Many taxa on coral reefs are characterized by weak genetic drift, extensive gene flow, and strong selection from complex biotic and abiotic environments, which together present a fascinating test of microevolutionary theory. Selection, gene flow, and hybridization have played and will continue to play an important role in the adaptation or extinction of coral reef taxa in the face of rapid environmental change, but research remains exceptionally limited compared to the urgent needs. Critical areas for future investigation include understanding evolutionary potential and the mechanisms of local adaptation, developing historical baselines, and building greater research capacity in the countries where most reef diversity is concentrated.
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Affiliation(s)
- Malin L Pinsky
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA;
| | - René D Clark
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
| | - Jaelyn T Bos
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
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11
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James J, Kastally C, Budde KB, González-Martínez SC, Milesi P, Pyhäjärvi T, Lascoux M. Between but Not Within-Species Variation in the Distribution of Fitness Effects. Mol Biol Evol 2023; 40:msad228. [PMID: 37832225 PMCID: PMC10630145 DOI: 10.1093/molbev/msad228] [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: 05/17/2023] [Revised: 09/04/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
New mutations provide the raw material for evolution and adaptation. The distribution of fitness effects (DFE) describes the spectrum of effects of new mutations that can occur along a genome, and is, therefore, of vital interest in evolutionary biology. Recent work has uncovered striking similarities in the DFE between closely related species, prompting us to ask whether there is variation in the DFE among populations of the same species, or among species with different degrees of divergence, that is whether there is variation in the DFE at different levels of evolution. Using exome capture data from six tree species sampled across Europe we characterized the DFE for multiple species, and for each species, multiple populations, and investigated the factors potentially influencing the DFE, such as demography, population divergence, and genetic background. We find statistical support for the presence of variation in the DFE at the species level, even among relatively closely related species. However, we find very little difference at the population level, suggesting that differences in the DFE are primarily driven by deep features of species biology, and those evolutionarily recent events, such as demographic changes and local adaptation, have little impact.
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Affiliation(s)
- Jennifer James
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- Swedish Collegium of Advanced Study, Uppsala University, Uppsala, Sweden
| | - Chedly Kastally
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
- Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Katharina B Budde
- Department of Forest Genetics and Forest Tree Breeding, Georg-August-University Goettingen, Goettingen, Germany
- Center of Biodiversity and Sustainable Land Use (CBL), University of Goettingen, Goettingen, Germany
| | - Santiago C González-Martínez
- National Research Institute for Agriculture, Food and the Environment (INRAE), University of Bordeaux, BIOGECO, Cestas, France
| | - Pascal Milesi
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory (SciLifeLab), Uppsala University, Uppsala, Sweden
| | - Tanja Pyhäjärvi
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
- Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Martin Lascoux
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
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12
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Orive ME, Barfield M, Holt RD. Partial Clonality Expands the Opportunity for Spatial Adaptation. Am Nat 2023; 202:681-698. [PMID: 37963114 DOI: 10.1086/726335] [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] [Indexed: 11/16/2023]
Abstract
AbstractReproductive mode may strongly impact adaptation in spatially varying populations linked by dispersal, especially when sexual and clonal offspring differ in dispersal. We determined how spatial structure affects adaptation in populations with mixed clonal and sexual reproduction. In a source-sink quantitative genetic deterministic model (with stabilizing selection around different optima), greater clonal reproduction or parent-offspring association (a measure of the part of the parent's phenotype other than the additive genetic component inherited by clonal offspring) increased the selective difference (difference between phenotypic optima) allowing sink populations to adapt. Given dispersal differences between clonally and sexually produced juveniles, adaptation increased with an increasing fraction of clonal dispersers. When considering migrational meltdown, partially clonal reproduction reduced cases where dispersal caused habitat loss. Stochastic individual-based simulations support these results, although the effect of differential dispersal was reversed, with decreased clonal dispersal allowing greater adaptation. These results parallel earlier findings that for an instantaneous shift in phenotypic optimum, increasing clonality allowed population persistence for a greater shift; here, selective change is spatial rather than temporal. These results may help explain the success of many partially clonal organisms in invading new habitats, complementing traditional explanations based on avoiding Allee effects.
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13
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Pita-Aquino JN, Bock DG, Baeckens S, Losos JB, Kolbe JJ. Stronger evidence for genetic ancestry than environmental conditions in shaping the evolution of a complex signalling trait during biological invasion. Mol Ecol 2023; 32:5558-5574. [PMID: 37698063 DOI: 10.1111/mec.17123] [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: 07/25/2022] [Accepted: 08/17/2023] [Indexed: 09/13/2023]
Abstract
Introductions of invasive species to new environments often result in rapid rates of trait evolution. While in some cases these evolutionary transitions are adaptive and driven by natural selection, they can also result from patterns of genetic and phenotypic variation associated with the invasion history. Here, we examined the brown anole (Anolis sagrei), a widespread invasive lizard for which genetic data have helped trace the sources of non-native populations. We focused on the dewlap, a complex signalling trait known to be subject to multiple selective pressures. We measured dewlap reflectance, pattern and size in 30 non-native populations across the southeastern United States. As well, we quantified environmental variables known to influence dewlap signal effectiveness, such as canopy openness. Further, we used genome-wide data to estimate genetic ancestry, perform association mapping and test for signatures of selection. We found that among-population variation in dewlap characteristics was best explained by genetic ancestry. This result was supported by genome-wide association mapping, which identified several ancestry-specific loci associated with dewlap traits. Despite the strong imprint of this aspect of the invasion history on dewlap variation, we also detected significant relationships between dewlap traits and local environmental conditions. However, we found limited evidence that dewlap-associated genetic variants have been subject to selection. Our study emphasizes the importance of genetic ancestry and admixture in shaping phenotypes during biological invasion, while leaving the role of selection unresolved, likely due to the polygenic genetic architecture of dewlaps and selection acting on many genes of small effect.
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Affiliation(s)
- Jessica N Pita-Aquino
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Dan G Bock
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Simon Baeckens
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Jonathan B Losos
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jason J Kolbe
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, USA
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14
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Lake TA, Briscoe Runquist RD, Flagel LE, Moeller DA. Chronosequence of invasion reveals minimal losses of population genomic diversity, niche expansion, and trait divergence in the polyploid, leafy spurge. Evol Appl 2023; 16:1680-1696. [PMID: 38020872 PMCID: PMC10660801 DOI: 10.1111/eva.13593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 07/05/2023] [Accepted: 08/25/2023] [Indexed: 12/01/2023] Open
Abstract
Rapid evolution may play an important role in the range expansion of invasive species and modify forecasts of invasion, which are the backbone of land management strategies. However, losses of genetic variation associated with colonization bottlenecks may constrain trait and niche divergence at leading range edges, thereby impacting management decisions that anticipate future range expansion. The spatial and temporal scales over which adaptation contributes to invasion dynamics remain unresolved. We leveraged detailed records of the ~130-year invasion history of the invasive polyploid plant, leafy spurge (Euphorbia virgata), across ~500 km in Minnesota, U.S.A. We examined the consequences of range expansion for population genomic diversity, niche breadth, and the evolution of germination behavior. Using genotyping-by-sequencing, we found some population structure in the range core, where introduction occurred, but panmixia among all other populations. Range expansion was accompanied by only modest losses in sequence diversity, with small, isolated populations at the leading edge harboring similar levels of diversity to those in the range core. The climatic niche expanded during most of the range expansion, and the niche of the range core was largely non-overlapping with the invasion front. Ecological niche models indicated that mean temperature of the warmest quarter was the strongest determinant of habitat suitability and that populations at the leading edge had the lowest habitat suitability. Guided by these findings, we tested for rapid evolution in germination behavior over the time course of range expansion using a common garden experiment and temperature manipulations. Germination behavior diverged from the early to late phases of the invasion, with populations from later phases having higher dormancy at lower temperatures. Our results suggest that trait evolution may have contributed to niche expansion during invasion and that distribution models, which inform future management planning, may underestimate invasion potential without accounting for evolution.
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Affiliation(s)
- Thomas A. Lake
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesotaUSA
| | | | - Lex E. Flagel
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesotaUSA
- GencoveLong Island CityNew YorkUSA
| | - David A. Moeller
- Department of Plant and Microbial BiologyUniversity of MinnesotaSt. PaulMinnesotaUSA
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15
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Rougemont Q, Leroy T, Rondeau EB, Koop B, Bernatchez L. Allele surfing causes maladaptation in a Pacific salmon of conservation concern. PLoS Genet 2023; 19:e1010918. [PMID: 37683018 PMCID: PMC10545117 DOI: 10.1371/journal.pgen.1010918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 10/02/2023] [Accepted: 08/11/2023] [Indexed: 09/10/2023] Open
Abstract
How various factors, including demography, recombination or genome duplication, may impact the efficacy of natural selection and the burden of deleterious mutations, is a central question in evolutionary biology and genetics. In this study, we show that key evolutionary processes, including variations in i) effective population size (Ne) ii) recombination rates and iii) chromosome inheritance, have influenced the genetic load and efficacy of selection in Coho salmon (Oncorhynchus kisutch), a widely distributed salmonid species on the west coast of North America. Using whole genome resequencing data from 14 populations at different migratory distances from their southern glacial refugium, we found evidence supporting gene surfing, wherein reduced Ne at the postglacial recolonization front, leads to a decrease in the efficacy of selection and a surf of deleterious alleles in the northernmost populations. Furthermore, our results indicate that recombination rates play a prime role in shaping the load along the genome. Additionally, we identified variation in polyploidy as a contributing factor to within-genome variation of the load. Overall, our results align remarkably well with expectations under the nearly neutral theory of molecular evolution. We discuss the fundamental and applied implications of these findings for evolutionary and conservation genomics.
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Affiliation(s)
- Quentin Rougemont
- Centre d’Ecologie Fonctionnelle et Evolutive, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Thibault Leroy
- GenPhySE, INRAE, INP, ENVT, Université de Toulouse, Auzeville- Tolosane, France
| | - Eric B. Rondeau
- Department of Fisheries and Ocean, Pacific Biological Station, Nanaimo, Canada
| | - Ben Koop
- Department of Biology, University of Victoria, Victoria, Canada
| | - Louis Bernatchez
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada
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16
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Zeitler L, Parisod C, Gilbert KJ. Purging due to self-fertilization does not prevent accumulation of expansion load. PLoS Genet 2023; 19:e1010883. [PMID: 37656747 PMCID: PMC10501686 DOI: 10.1371/journal.pgen.1010883] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 09/14/2023] [Accepted: 07/25/2023] [Indexed: 09/03/2023] Open
Abstract
As species expand their geographic ranges, colonizing populations face novel ecological conditions, such as new environments and limited mates, and suffer from evolutionary consequences of demographic change through bottlenecks and mutation load accumulation. Self-fertilization is often observed at species range edges and, in addition to countering the lack of mates, is hypothesized as an evolutionary advantage against load accumulation through increased homozygosity and purging. We study how selfing impacts the accumulation of genetic load during range expansion via purging and/or speed of colonization. Using simulations, we disentangle inbreeding effects due to demography versus due to selfing and find that selfers expand faster, but still accumulate load, regardless of mating system. The severity of variants contributing to this load, however, differs across mating system: higher selfing rates purge large-effect recessive variants leaving a burden of smaller-effect alleles. We compare these predictions to the mixed-mating plant Arabis alpina, using whole-genome sequences from refugial outcrossing populations versus expanded selfing populations. Empirical results indicate accumulation of expansion load along with evidence of purging in selfing populations, concordant with our simulations, suggesting that while purging is a benefit of selfing evolving during range expansions, it is not sufficient to prevent load accumulation due to range expansion.
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Affiliation(s)
- Leo Zeitler
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Christian Parisod
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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17
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Kläy L, Girardin L, Calvez V, Débarre F. Pulled, pushed or failed: the demographic impact of a gene drive can change the nature of its spatial spread. J Math Biol 2023; 87:30. [PMID: 37454310 DOI: 10.1007/s00285-023-01926-4] [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: 10/26/2022] [Revised: 03/10/2023] [Accepted: 04/18/2023] [Indexed: 07/18/2023]
Abstract
Understanding the temporal spread of gene drive alleles-alleles that bias their own transmission-through modeling is essential before any field experiments. In this paper, we present a deterministic reaction-diffusion model describing the interplay between demographic and allelic dynamics, in a one-dimensional spatial context. We focused on the traveling wave solutions, and more specifically, on the speed of gene drive invasion (if successful). We considered various timings of gene conversion (in the zygote or in the germline) and different probabilities of gene conversion (instead of assuming 100[Formula: see text] conversion as done in a previous work). We compared the types of propagation when the intrinsic growth rate of the population takes extreme values, either very large or very low. When it is infinitely large, the wave can be either successful or not, and, if successful, it can be either pulled or pushed, in agreement with previous studies (extended here to the case of partial conversion). In contrast, it cannot be pushed when the intrinsic growth rate is vanishing. In this case, analytical results are obtained through an insightful connection with an epidemiological SI model. We conducted extensive numerical simulations to bridge the gap between the two regimes of large and low growth rate. We conjecture that, if it is pulled in the two extreme regimes, then the wave is always pulled, and the wave speed is independent of the growth rate. This occurs for instance when the fitness cost is small enough, or when there is stable coexistence of the drive and the wild-type in the population after successful drive invasion. Our model helps delineate the conditions under which demographic dynamics can affect the spread of a gene drive.
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Affiliation(s)
- Léna Kläy
- Institute of Ecology and Environmental Sciences Paris (IEES Paris), Sorbonne Université, CNRS, IRD, INRAE, Université Paris Est Creteil, Université de Paris, Paris Cedex 5, Paris, France.
| | - Léo Girardin
- Institut Camille Jordan, UMR 5208 CNRS and Universite Claude Bernard Lyon 1, Villeurbanne, France
| | - Vincent Calvez
- Institut Camille Jordan, UMR 5208 CNRS and Universite Claude Bernard Lyon 1, Villeurbanne, France
| | - Florence Débarre
- Institute of Ecology and Environmental Sciences Paris (IEES Paris), Sorbonne Université, CNRS, IRD, INRAE, Université Paris Est Creteil, Université de Paris, Paris Cedex 5, Paris, France
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18
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Blois L, de Miguel M, Bert P, Girollet N, Ollat N, Rubio B, Segura V, Voss‐Fels KP, Schmid J, Marguerit E. Genetic structure and first genome-wide insights into the adaptation of a wild relative of grapevine, Vitis berlandieri. Evol Appl 2023; 16:1184-1200. [PMID: 37360024 PMCID: PMC10286229 DOI: 10.1111/eva.13566] [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: 10/17/2022] [Revised: 05/16/2023] [Accepted: 05/22/2023] [Indexed: 06/28/2023] Open
Abstract
In grafted plants, such as grapevine, increasing the diversity of rootstocks available to growers is an ideal strategy for helping plants to adapt to climate change. The rootstocks used for grapevine are hybrids of various American Vitis, including V. berlandieri. The rootstocks currently use in vineyards are derived from breeding programs involving very small numbers of parental individuals. We investigated the structure of a natural population of V. berlandieri and the association of genetic diversity with environmental variables. In this study, we collected seeds from 78 wild V. berlandieri plants in Texas after open fertilization. We genotyped 286 individuals to describe the structure of the population, and environmental information collected at the sampling site made it possible to perform genome-environment association analysis (GEA). De novo long-read whole-genome sequencing was performed on V. berlandieri and a STRUCTURE analysis was performed. We identified and filtered 104,378 SNPs. We found that there were two subpopulations associated with differences in elevation, temperature, and rainfall between sampling sites. GEA identified three QTL for elevation and 15 QTL for PCA coordinates based on environmental parameter variability. This original study is the first GEA study to be performed on a population of grapevines sampled in natural conditions. Our results shed new light on rootstock genetics and could open up possibilities for introducing greater diversity into genetic improvement programs for grapevine rootstocks.
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Affiliation(s)
- Louis Blois
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
- Department of Grapevine BreedingGeisenheim UniversityGeisenheimGermany
| | - Marina de Miguel
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
| | - Pierre‐François Bert
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
| | - Nabil Girollet
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
| | - Nathalie Ollat
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
| | - Bernadette Rubio
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
| | - Vincent Segura
- AGAP Institut, Univ Montpellier, CIRAD, INRAE, Institut AgroMontpellierFrance
| | - Kai P. Voss‐Fels
- Department of Grapevine BreedingGeisenheim UniversityGeisenheimGermany
| | - Joachim Schmid
- Department of Grapevine BreedingGeisenheim UniversityGeisenheimGermany
| | - Elisa Marguerit
- EGFV, Univ. Bordeaux, Bordeaux Sciences Agro, INRAE, ISVVVillenave d'OrnonFrance
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19
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Robinson J, Kyriazis CC, Yuan SC, Lohmueller KE. Deleterious Variation in Natural Populations and Implications for Conservation Genetics. Annu Rev Anim Biosci 2023; 11:93-114. [PMID: 36332644 PMCID: PMC9933137 DOI: 10.1146/annurev-animal-080522-093311] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Deleterious mutations decrease reproductive fitness and are ubiquitous in genomes. Given that many organisms face ongoing threats of extinction, there is interest in elucidating the impact of deleterious variation on extinction risk and optimizing management strategies accounting for such mutations. Quantifying deleterious variation and understanding the effects of population history on deleterious variation are complex endeavors because we do not know the strength of selection acting on each mutation. Further, the effect of demographic history on deleterious mutations depends on the strength of selection against the mutation and the degree of dominance. Here we clarify how deleterious variation can be quantified and studied in natural populations. We then discuss how different demographic factors, such as small population size, nonequilibrium population size changes, inbreeding, and gene flow, affect deleterious variation. Lastly, we provide guidance on studying deleterious variation in nonmodel populations of conservation concern.
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Affiliation(s)
- Jacqueline Robinson
- Institute for Human Genetics, University of California, San Francisco, California, USA;
| | - Christopher C Kyriazis
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA; , ,
| | - Stella C Yuan
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA; , ,
| | - Kirk E Lohmueller
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA; , , .,Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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20
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Devloo‐Delva F, Burridge CP, Kyne PM, Brunnschweiler JM, Chapman DD, Charvet P, Chen X, Cliff G, Daly R, Drymon JM, Espinoza M, Fernando D, Barcia LG, Glaus K, González‐Garza BI, Grant MI, Gunasekera RM, Hernandez S, Hyodo S, Jabado RW, Jaquemet S, Johnson G, Ketchum JT, Magalon H, Marthick JR, Mollen FH, Mona S, Naylor GJP, Nevill JEG, Phillips NM, Pillans RD, Postaire BD, Smoothey AF, Tachihara K, Tillet BJ, Valerio‐Vargas JA, Feutry P. From rivers to ocean basins: The role of ocean barriers and philopatry in the genetic structuring of a cosmopolitan coastal predator. Ecol Evol 2023; 13:e9837. [PMID: 36844667 PMCID: PMC9944188 DOI: 10.1002/ece3.9837] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/31/2023] [Accepted: 01/31/2023] [Indexed: 02/24/2023] Open
Abstract
The Bull Shark (Carcharhinus leucas) faces varying levels of exploitation around the world due to its coastal distribution. Information regarding population connectivity is crucial to evaluate its conservation status and local fishing impacts. In this study, we sampled 922 putative Bull Sharks from 19 locations in the first global assessment of population structure of this cosmopolitan species. Using a recently developed DNA-capture approach (DArTcap), samples were genotyped for 3400 nuclear markers. Additionally, full mitochondrial genomes of 384 Indo-Pacific samples were sequenced. Reproductive isolation was found between and across ocean basins (eastern Pacific, western Atlantic, eastern Atlantic, Indo-West Pacific) with distinct island populations in Japan and Fiji. Bull Sharks appear to maintain gene flow using shallow coastal waters as dispersal corridors, whereas large oceanic distances and historical land-bridges act as barriers. Females tend to return to the same area for reproduction, making them more susceptible to local threats and an important focus for management actions. Given these behaviors, the exploitation of Bull Sharks from insular populations, such as Japan and Fiji, may instigate local decline that cannot readily be replenished by immigration, which can in turn affect ecosystem dynamics and functions. These data also supported the development of a genetic panel to ascertain the population of origin, which will be useful in monitoring the trade of fisheries products and assessing population-level impacts of this harvest.
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Affiliation(s)
- Floriaan Devloo‐Delva
- Oceans and Atmosphere, CSIROHobartTasmaniaAustralia
- Quantitative Marine Science, Institute for Marine and Antarctic Studies, University of TasmaniaHobartTasmaniaAustralia
- Discipline of Biological Sciences, School of Natural SciencesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Christopher P. Burridge
- Discipline of Biological Sciences, School of Natural SciencesUniversity of TasmaniaHobartTasmaniaAustralia
| | - Peter M. Kyne
- Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinNorthern TerritoryAustralia
| | | | - Demian D. Chapman
- Department of Biological SciencesFlorida International UniversityNorth MiamiFloridaUSA
| | - Patricia Charvet
- Programa de Pós‐graduação em Sistemática, Uso e Conservação da BiodiversidadeUniversidade Federal do Ceará (PPGSis ‐ UFC)FortalezaBrazil
| | - Xiao Chen
- College of Veterinary MedicineSouth China Agricultural UniversityGuangzhouChina
| | - Geremy Cliff
- KwaZulu‐Natal Sharks Board, Umhlanga 4320, South Africa and School of Life SciencesUniversity of KwaZulu‐NatalDurbanSouth Africa
| | - Ryan Daly
- Oceanographic Research Institute, South African Association for Marine Biological Research, PointDurbanSouth Africa
- South African Institute for Aquatic BiodiversityMkhandaSouth Africa
| | - J. Marcus Drymon
- Coastal Research and Extension CenterMississippi State UniversityBiloxiMississippiUSA
- Mississippi‐Alabama Sea Grant ConsortiumOcean SpringsMississippiUSA
| | - Mario Espinoza
- Centro de Investigación en Ciencias del Mar y Limnología & Escuela de BiologíaUniversidad de Costa Rica, San Pedro de Montes de OcaSan JoséCosta Rica
| | | | - Laura Garcia Barcia
- Department of Biological SciencesFlorida International UniversityNorth MiamiFloridaUSA
| | - Kerstin Glaus
- Faculty of Science, Technology and Environment, School of Marine StudiesThe University of the South PacificSuvaFiji
| | | | - Michael I. Grant
- College of Science and Engineering, Centre for Sustainable Tropical Fisheries and AquacultureJames Cook UniversityTownsvilleQueenslandAustralia
| | | | - Sebastian Hernandez
- Biomolecular Laboratory, Center for International ProgramsUniversidad VERITASSan JoséCosta Rica
- Sala de Colecciones, Facultad de Ciencias del MarUniversidad Católica del NorteCoquimboChile
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research InstituteUniversity of TokyoKashiwa, ChibaJapan
| | - Rima W. Jabado
- College of Science and Engineering, Centre for Sustainable Tropical Fisheries and AquacultureJames Cook UniversityTownsvilleQueenslandAustralia
- Elasmo ProjectDubaiUnited Arab Emirates
| | - Sébastien Jaquemet
- UMR ENTROPIE (Université de La Réunion, Université de Nouvelle‐Calédonie, IRD, CNRS, IFREMER), Faculté des Sciences et TechnologiesUniversité de La RéunionCedex 09, La RéunionFrance
| | - Grant Johnson
- Department of Industry, Tourism and Trade, Aquatic Resource Research UnitDarwinNorthern TerritoryAustralia
| | | | - Hélène Magalon
- UMR ENTROPIE (Université de La Réunion, Université de Nouvelle‐Calédonie, IRD, CNRS, IFREMER), Faculté des Sciences et TechnologiesUniversité de La RéunionCedex 09, La RéunionFrance
| | - James R. Marthick
- Menzies Institute for Medical ResearchUniversity of TasmaniaHobartTasmaniaAustralia
| | | | - Stefano Mona
- Institut de Systématique, Evolution, Biodiversité, ISYEB (UMR 7205), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHEUniversité des AntillesParisFrance
- EPHEPSL Research UniversityParisFrance
| | - Gavin J. P. Naylor
- Florida Museum of Natural HistoryUniversity of FloridaGainesvilleFloridaUSA
| | | | - Nicole M. Phillips
- School of Biological, Environmental and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | | | - Bautisse D. Postaire
- UMR ENTROPIE (Université de La Réunion, Université de Nouvelle‐Calédonie, IRD, CNRS, IFREMER), Faculté des Sciences et TechnologiesUniversité de La RéunionCedex 09, La RéunionFrance
| | - Amy F. Smoothey
- NSW Department of Primary Industries, Fisheries ResearchSydney Institute of Marine ScienceMosmanNew South WalesAustralia
| | - Katsunori Tachihara
- Laboratory of Fisheries Biology and Coral Reef Studies, Faculty of ScienceUniversity of Ryukyus, NishiharaOkinawaJapan
| | - Bree J. Tillet
- Translational Research Institute, University of Queensland Diamantina InstituteBrisbaneQueenslandAustralia
| | - Jorge A. Valerio‐Vargas
- Centro de Investigación en Ciencias del Mar y Limnología & Escuela de BiologíaUniversidad de Costa Rica, San Pedro de Montes de OcaSan JoséCosta Rica
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21
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Bernos TA, Avlijaš S, Hill J, Morissette O, Ricciardi A, Mandrak NE, Jeffries KM. Genetic diversity and structure of a recent fish invasion: Tench ( Tinca tinca) in eastern North America. Evol Appl 2023; 16:173-188. [PMID: 36699124 PMCID: PMC9850014 DOI: 10.1111/eva.13520] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/22/2022] [Accepted: 12/02/2022] [Indexed: 01/20/2023] Open
Abstract
Introduced and geographically expanding populations experience similar eco-evolutionary challenges, including founder events, genetic bottlenecks, and novel environments. Theory predicts that reduced genetic diversity resulting from such phenomena limits the success of introduced populations. Using 1900 SNPs obtained from restriction-site-associated DNA sequencing, we evaluated hypotheses related to the invasion history and connectivity of an invasive population of Tench (Tinca tinca), a Eurasian freshwater fish that has been expanding geographically in eastern North America for three decades. Consistent with the reported history of a single introduction event, our findings suggest that multiple introductions from distinct genetic sources are unlikely as Tench had a small effective population size (~114 [95% CI = 106-123] individuals), no strong population subdivision across time and space, and evidence of a recent genetic bottleneck. The large genetic neighbourhood size (220 km) and weak within-population genetic substructure suggested high connectivity across the invaded range, despite the relatively large area occupied. There was some evidence for a small decay in genetic diversity as the species expanded northward, but not southward, into new habitats. As eradicating the species within a ~112 km radius would be necessary to prevent recolonization, eradicating Tench is likely not feasible at watershed-and possibly local-scales. Management should instead focus on reducing abundance in priority conservation areas to mitigate adverse impacts. Our study indicates that introduced populations can thrive and exhibit relatively high levels of genetic diversity despite severe bottlenecks (<1.5% of the ancestral effective population size) and suggests that landscape heterogeneity and population demographics can generate variability in spatial patterns of genetic diversity within a single range expansion.
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Affiliation(s)
- Thaïs A. Bernos
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
- Department of Biological SciencesUniversity of Toronto ScarboroughScarboroughOntarioCanada
| | - Sunčica Avlijaš
- Redpath MuseumMcGill UniversityMontrealQuébecCanada
- Department of BiologyMcGill UniversityMontrealQuébecCanada
| | - Jaclyn Hill
- Maurice Lamontagne InstituteFisheries and Oceans CanadaMont‐JoliQuébecCanada
| | - Olivier Morissette
- Département des Sciences FondamentalesUniversité du Québec à ChicoutimiChicoutimiQuébecCanada
| | | | - Nicholas E. Mandrak
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
| | - Kenneth M. Jeffries
- Department of Biological SciencesUniversity of ManitobaWinnipegManitobaCanada
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22
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Schlichta F, Moinet A, Peischl S, Excoffier L. The Impact of Genetic Surfing on Neutral Genomic Diversity. Mol Biol Evol 2022; 39:msac249. [PMID: 36403964 PMCID: PMC9703594 DOI: 10.1093/molbev/msac249] [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] [Indexed: 11/22/2022] Open
Abstract
Range expansions have been common in the history of most species. Serial founder effects and subsequent population growth at expansion fronts typically lead to a loss of genomic diversity along the expansion axis. A frequent consequence is the phenomenon of "gene surfing," where variants located near the expanding front can reach high frequencies or even fix in newly colonized territories. Although gene surfing events have been characterized thoroughly for a specific locus, their effects on linked genomic regions and the overall patterns of genomic diversity have been little investigated. In this study, we simulated the evolution of whole genomes during several types of 1D and 2D range expansions differing by the extent of migration, founder events, and recombination rates. We focused on the characterization of local dips of diversity, or "troughs," taken as a proxy for surfing events. We find that, for a given recombination rate, once we consider the amount of diversity lost since the beginning of the expansion, it is possible to predict the initial evolution of trough density and their average width irrespective of the expansion condition. Furthermore, when recombination rates vary across the genome, we find that troughs are over-represented in regions of low recombination. Therefore, range expansions can leave local and global genomic signatures often interpreted as evidence of past selective events. Given the generality of our results, they could be used as a null model for species having gone through recent expansions, and thus be helpful to correctly interpret many evolutionary biology studies.
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Affiliation(s)
- Flávia Schlichta
- Computational and Molecular Population Genetics lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Antoine Moinet
- Computational and Molecular Population Genetics lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
- Interfaculty Bioinformatics Unit, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Stephan Peischl
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
- Interfaculty Bioinformatics Unit, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Laurent Excoffier
- Computational and Molecular Population Genetics lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
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23
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Muir CD, Van Den Elzen CL, Angert AL. Selection on early survival does not explain germination rate clines in Mimulus cardinalis. AMERICAN JOURNAL OF BOTANY 2022; 109:1811-1821. [PMID: 36317645 DOI: 10.1002/ajb2.16076] [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: 01/14/2021] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 06/16/2023]
Abstract
PREMISE Many traits covary with environmental gradients to form phenotypic clines. While local adaptation to the environment can generate phenotypic clines, other nonadaptive processes may also. If local adaptation causes phenotypic clines, then the direction of genotypic selection on traits should shift from one end of the cline to the other. Traditionally, genotypic selection on non-Gaussian traits like germination rate have been hampered because it is challenging to measure their genetic variance. METHODS Here we used quantitative genetics and reciprocal transplants to test whether a previously discovered cline in germination rate showed additional signatures of adaptation in the scarlet monkeyflower (Mimulus cardinalis). We measured genotypic and population level covariation between germination rate and early survival, a component of fitness. We developed a novel discrete log-normal model to estimate genetic variance in germination rate. RESULTS Contrary to our adaptive hypothesis, we found no evidence that genetic variation in germination rate contributed to variation in early survival. Across populations, southern populations in both gardens germinated earlier and survived more. CONCLUSIONS Southern populations have higher early survival but it is not caused by faster germination. This pattern is consistent with nonadaptive forces driving the phenotypic cline in germination rate, but future work will need to assess whether there is selection at other life stages. This statistical framework should help expand quantitative genetic analyses for other waiting-time traits.
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Affiliation(s)
- Christopher D Muir
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- School of Life Sciences, University of Hawai'i, Honolulu, HI, 96822, USA
| | - Courtney L Van Den Elzen
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Amy L Angert
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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Clark EI, Bitume EV, Bean DW, Stahlke AR, Hohenlohe PA, Hufbauer RA. Evolution of reproductive life‐history and dispersal traits during the range expansion of a biological control agent. Evol Appl 2022; 15:2089-2099. [DOI: 10.1111/eva.13502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022] Open
Affiliation(s)
- Eliza I. Clark
- Graduate Degree Program in Ecology, Department of Agricultural Biology Colorado State University Fort Collins Colorado USA
| | - Ellyn V. Bitume
- Pacific Southwest Research Station Institute of Pacific Islands Forestry, USDA Forest Service Hilo Hawaii USA
| | - Dan W. Bean
- Colorado Department of Agriculture Palisade Insectary Palisade Colorado USA
| | - Amanda R. Stahlke
- Initiative for Bioinformatics and Evolutionary Studies, Department of Biological Sciences University of Idaho Moscow Idaho USA
- Bee Research Laboratory USDA, Agricultural Research Service, Beltsville Agricultural Research Center Beltsville Maryland USA
| | - Paul A. Hohenlohe
- Initiative for Bioinformatics and Evolutionary Studies, Department of Biological Sciences University of Idaho Moscow Idaho USA
| | - Ruth A. Hufbauer
- Graduate Degree Program in Ecology, Department of Agricultural Biology Colorado State University Fort Collins Colorado USA
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25
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Pang H, Lin J, Luo S, Huang G, Li X, Xie Z, Zhou Z. The missing heritability in type 1 diabetes. Diabetes Obes Metab 2022; 24:1901-1911. [PMID: 35603907 PMCID: PMC9545639 DOI: 10.1111/dom.14777] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/04/2022] [Accepted: 05/17/2022] [Indexed: 12/15/2022]
Abstract
Type 1 diabetes (T1D) is a complex autoimmune disease characterized by an absolute deficiency of insulin. It affects more than 20 million people worldwide and imposes an enormous financial burden on patients. The underlying pathogenic mechanisms of T1D are still obscure, but it is widely accepted that both genetics and the environment play an important role in its onset and development. Previous studies have identified more than 60 susceptible loci associated with T1D, explaining approximately 80%-85% of the heritability. However, most identified variants confer only small increases in risk, which restricts their potential clinical application. In addition, there is still a so-called 'missing heritability' phenomenon. While the gap between known heritability and true heritability in T1D is small compared with that in other complex traits and disorders, further elucidation of T1D genetics has the potential to bring novel insights into its aetiology and provide new therapeutic targets. Many hypotheses have been proposed to explain the missing heritability, including variants remaining to be found (variants with small effect sizes, rare variants and structural variants) and interactions (gene-gene and gene-environment interactions; e.g. epigenetic effects). In the following review, we introduce the possible sources of missing heritability and discuss the existing related knowledge in the context of T1D.
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Affiliation(s)
- Haipeng Pang
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Jian Lin
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Shuoming Luo
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Gan Huang
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Xia Li
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Zhiguo Xie
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
| | - Zhiguang Zhou
- National Clinical Research Center for Metabolic Diseases, Key Laboratory of Diabetes Immunology (Central South University), Ministry of Education, and Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangshaChina
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26
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Lye Z, Choi JY, Purugganan MD. Deleterious mutations and the rare allele burden on rice gene expression. Mol Biol Evol 2022; 39:6693943. [PMID: 36073358 PMCID: PMC9512150 DOI: 10.1093/molbev/msac193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Deleterious genetic variation is maintained in populations at low frequencies. Under a model of stabilizing selection, rare (and presumably deleterious) genetic variants are associated with increase or decrease in gene expression from some intermediate optimum. We investigate this phenomenon in a population of largely Oryza sativa ssp. indica rice landraces under normal unstressed wet and stressful drought field conditions. We include single nucleotide polymorphisms, insertion/deletion mutations, and structural variants in our analysis and find a stronger association between rare variants and gene expression outliers under the stress condition. We also show an association of the strength of this rare variant effect with linkage, gene expression levels, network connectivity, local recombination rate, and fitness consequence scores, consistent with the stabilizing selection model of gene expression.
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Affiliation(s)
- Zoe Lye
- Center for Genomics and Systems Biology, New York University, New York, NY 10003
| | - Jae Young Choi
- Center for Genomics and Systems Biology, New York University, New York, NY 10003
| | - Michael D Purugganan
- Center for Genomics and Systems Biology, New York University, New York, NY 10003.,Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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27
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Rare and population-specific functional variation across pig lines. Genet Sel Evol 2022; 54:39. [PMID: 35659233 PMCID: PMC9164375 DOI: 10.1186/s12711-022-00732-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/17/2022] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND It is expected that functional, mainly missense and loss-of-function (LOF), and regulatory variants are responsible for most phenotypic differences between breeds and genetic lines of livestock species that have undergone diverse selection histories. However, there is still limited knowledge about the existing missense and LOF variation in commercial livestock populations, in particular regarding population-specific variation and how it can affect applications such as across-breed genomic prediction. METHODS We re-sequenced the whole genome of 7848 individuals from nine commercial pig lines (average sequencing coverage: 4.1×) and imputed whole-genome genotypes for 440,610 pedigree-related individuals. The called variants were categorized according to predicted functional annotation (from LOF to intergenic) and prevalence level (number of lines in which the variant segregated; from private to widespread). Variants in each category were examined in terms of their distribution along the genome, alternative allele frequency, per-site Wright's fixation index (FST), individual load, and association to production traits. RESULTS Of the 46 million called variants, 28% were private (called in only one line) and 21% were widespread (called in all nine lines). Genomic regions with a low recombination rate were enriched with private variants. Low-prevalence variants (called in one or a few lines only) were enriched for lower allele frequencies, lower FST, and putatively functional and regulatory roles (including LOF and deleterious missense variants). On average, individuals carried fewer private deleterious missense alleles than expected compared to alleles with other predicted consequences. Only a small subset of the low-prevalence variants had intermediate allele frequencies and explained small fractions of phenotypic variance (up to 3.2%) of production traits. The significant low-prevalence variants had higher per-site FST than the non-significant ones. These associated low-prevalence variants were tagged by other more widespread variants in high linkage disequilibrium, including intergenic variants. CONCLUSIONS Most low-prevalence variants have low minor allele frequencies and only a small subset of low-prevalence variants contributed detectable fractions of phenotypic variance of production traits. Accounting for low-prevalence variants is therefore unlikely to noticeably benefit across-breed analyses, such as the prediction of genomic breeding values in a population using reference populations of a different genetic background.
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Eghdami A, Paulose J, Fusco D. Branching structure of genealogies in spatially growing populations and its implications for population genetics inference. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:294008. [PMID: 35510713 DOI: 10.1088/1361-648x/ac6cd9] [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: 12/27/2021] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Spatial models where growth is limited to the population edge have been instrumental to understanding the population dynamics and the clone size distribution in growing cellular populations, such as microbial colonies and avascular tumours. A complete characterization of the coalescence process generated by spatial growth is still lacking, limiting our ability to apply classic population genetics inference to spatially growing populations. Here, we start filling this gap by investigating the statistical properties of the cell lineages generated by the two dimensional Eden model, leveraging their physical analogy with directed polymers. Our analysis provides quantitative estimates for population measurements that can easily be assessed via sequencing, such as the average number of segregating sites and the clone size distribution of a subsample of the population. Our results not only reveal remarkable features of the genealogies generated during growth, but also highlight new properties that can be misinterpreted as signs of selection if non-spatial models are inappropriately applied.
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Affiliation(s)
- Armin Eghdami
- Department of Physics, University of Cambridge, Cambridge, CB3 0HE, United Kingdom
| | - Jayson Paulose
- Department of Physics and Institute for Fundamental Science, University of Oregon, Eugene, OR 97401, United States of America
| | - Diana Fusco
- Department of Physics, University of Cambridge, Cambridge, CB3 0HE, United Kingdom
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29
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Orsucci M, Yang X, Vanikiotis T, Guerrina M, Duan T, Lascoux M, Glémin S. Competitive ability depends on mating system and ploidy level across Capsella species. ANNALS OF BOTANY 2022; 129:697-708. [PMID: 35325927 PMCID: PMC9113120 DOI: 10.1093/aob/mcac044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 10/14/2021] [Accepted: 03/23/2022] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIMS Self-fertilization is often associated with ecological traits corresponding to the ruderal strategy, and selfers are expected to be less competitive than outcrossers, either because of a colonization/competition trade-off or because of the deleterious genetic effects of selfing. Range expansion could reduce further competitive ability while polyploidy could mitigate the effects of selfing. If pollinators are not limited, individual fitness is thus expected to be higher in outcrossers than in selfers and, within selfers, in polyploids than in diploids. Although often proposed in the botanical literature and also suggested by meta-analyses, these predictions have not been directly tested yet. METHODS In order to compare fitness and the competitive ability of four Capsella species with a different mating system and ploidy level, we combined two complementary experiments. First, we carried out an experiment outdoors in north-west Greece, i.e. within the range of the obligate outcrossing species, C. grandiflora, where several life history traits were measured under two different disturbance treatments, weeded plots vs. unweeded plots. To better control competition and to remove potential effects of local adaptation of the outcrosser, we also performed a similar competition experiment but under growth chamber conditions. KEY RESULTS In the outdoor experiment, disturbance of the environment did not affect the phenotype in any of the four species. For most traits, the obligate outcrossing species performed better than all selfing species. In contrast, polyploids did not survive or reproduce better than diploids. Under controlled conditions, as in the field experiment, the outcrosser had a higher fitness than selfing species and was less affected by competition. Finally, contrary to the outdoor experiment where the two behaved identically, polyploid selfers were less affected by competition than diploid selfes. CONCLUSIONS In the Capsella genus, selfing induces lower fitness than outcrossing and can also reduce competitive ability. The effect of polyploidy is, however, unclear. These results highlight the possible roles of ecological context in the evolution of selfing species.
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Affiliation(s)
- Marion Orsucci
- Department of Ecology and Genetics, Evolutionary Biology Centre and Science for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
- Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Xuyue Yang
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Theofilos Vanikiotis
- Department of Biological Applications & Technology, University of Ioannina, Leof. S. Niarchou GR-451 10, Ioannina, Greece
| | - Maria Guerrina
- Department of Ecology and Genetics, Evolutionary Biology Centre and Science for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
| | - Tianlin Duan
- Department of Ecology and Genetics, Evolutionary Biology Centre and Science for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
| | - Martin Lascoux
- Department of Ecology and Genetics, Evolutionary Biology Centre and Science for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
| | - Sylvain Glémin
- Department of Ecology and Genetics, Evolutionary Biology Centre and Science for Life Laboratory, Uppsala University, 75236 Uppsala, Sweden
- UMR CNRS 6553 ECOBIO, Campus Beaulieu, bât 14a, CS 74205, 35042 Rennes, France
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30
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Evidence for continent-wide convergent evolution and stasis throughout 150 y of a biological invasion. Proc Natl Acad Sci U S A 2022; 119:e2107584119. [PMID: 35476511 PMCID: PMC9170017 DOI: 10.1073/pnas.2107584119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Adaptive evolution can help species to persist and spread in new environments, but it is unclear how the rate and duration of adaptive evolution vary throughout species ranges and on the decadal timescales most relevant to managing biodiversity for the 21st century. Using herbarium records, we reconstruct 150 y of evolution in an invasive plant as it spread across North America. Flowering phenology evolves to adapt to local growing seasons throughout the range but stalls after about a century. This punctuated, convergent evolution recapitulates long-term dynamics in the fossil record, implicating limits to evolutionary rates that are not evident for the first century of spread. The extent to which evolution can rescue a species from extinction, or facilitate range expansion, depends critically on the rate, duration, and geographical extent of the evolutionary response to natural selection. Adaptive evolution can occur quickly, but the duration and geographical extent of contemporary evolution in natural systems remain poorly studied. This is particularly true for species with large geographical ranges and for timescales that lie between “long-term” field experiments and the fossil record. Here, we introduce the Virtual Common Garden (VCG) to investigate phenotypic evolution in natural history collections while controlling for phenotypic plasticity in response to local growing conditions. Reconstructing 150 y of evolution in Lythrum salicaria (purple loosestrife) as it invaded North America, we analyze phenology measurements of 3,429 herbarium records, reconstruct growing conditions from more than 12 million local temperature records, and validate predictions across three common gardens spanning 10° of latitude. We find that phenological clines have evolved repeatedly throughout the range, during the first century of evolution. Thereafter, the rate of microevolution stalls, recapitulating macroevolutionary stasis observed in the fossil record. Our study demonstrates that preserved specimens are a critical resource for investigating limits to evolution in natural populations. Our results show how natural selection and trade-offs measured in field studies predict adaptive divergence observable in herbarium specimens over 15 decades at a continental scale.
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Johri P, Aquadro CF, Beaumont M, Charlesworth B, Excoffier L, Eyre-Walker A, Keightley PD, Lynch M, McVean G, Payseur BA, Pfeifer SP, Stephan W, Jensen JD. Recommendations for improving statistical inference in population genomics. PLoS Biol 2022; 20:e3001669. [PMID: 35639797 PMCID: PMC9154105 DOI: 10.1371/journal.pbio.3001669] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The field of population genomics has grown rapidly in response to the recent advent of affordable, large-scale sequencing technologies. As opposed to the situation during the majority of the 20th century, in which the development of theoretical and statistical population genetic insights outpaced the generation of data to which they could be applied, genomic data are now being produced at a far greater rate than they can be meaningfully analyzed and interpreted. With this wealth of data has come a tendency to focus on fitting specific (and often rather idiosyncratic) models to data, at the expense of a careful exploration of the range of possible underlying evolutionary processes. For example, the approach of directly investigating models of adaptive evolution in each newly sequenced population or species often neglects the fact that a thorough characterization of ubiquitous nonadaptive processes is a prerequisite for accurate inference. We here describe the perils of these tendencies, present our consensus views on current best practices in population genomic data analysis, and highlight areas of statistical inference and theory that are in need of further attention. Thereby, we argue for the importance of defining a biologically relevant baseline model tuned to the details of each new analysis, of skepticism and scrutiny in interpreting model fitting results, and of carefully defining addressable hypotheses and underlying uncertainties.
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Affiliation(s)
- Parul Johri
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Charles F. Aquadro
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Mark Beaumont
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Brian Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Laurent Excoffier
- Institute of Ecology and Evolution, University of Berne, Berne, Switzerland
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Peter D. Keightley
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael Lynch
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Gil McVean
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Bret A. Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Susanne P. Pfeifer
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | | | - Jeffrey D. Jensen
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
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Perrier A, Sánchez‐Castro D, Willi Y. Environment dependence of the expression of mutational load and species' range limits. J Evol Biol 2022; 35:731-741. [PMID: 35290676 PMCID: PMC9314787 DOI: 10.1111/jeb.13997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/10/2022] [Accepted: 02/21/2022] [Indexed: 12/21/2022]
Abstract
Theoretical and empirical research on the causes of species' range limits suggest the contribution of several intrinsic and extrinsic factors, with potentially complex interactions among them. An intrinsic factor proposed by recent theory is mutational load increasing towards range edges because of genetic drift. Furthermore, environmental quality may decline towards range edges and enhance the expression of load. Here, we tested whether the expression of mutational load associated with range limits in the North American plant Arabidopsis lyrata was enhanced under stressful environmental conditions by comparing the performance of within- versus between-population crosses at common garden sites across the species' distribution and beyond. Heterosis, reflecting the expression of load, increased with heightened estimates of genomic load and with environmental stress caused by warming, but the interaction was not significant. We conclude that range-edge populations suffer from a twofold genetic Allee effect caused by increased mutational load and stress-dependent load linked to general heterozygote deficiency, but there is no synergistic effect between them.
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Affiliation(s)
- Antoine Perrier
- Department of BiologyUniversity of VirginiaCharlottesvilleVirginiaUSA
- Department of Environmental SciencesUniversity of BaselBaselSwitzerland
| | | | - Yvonne Willi
- Department of Environmental SciencesUniversity of BaselBaselSwitzerland
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de Pedro M, Mayol M, González-Martínez SC, Regalado I, Riba M. Environmental patterns of adaptation after range expansion in Leontodon longirostris: The effect of phenological events on fitness-related traits. AMERICAN JOURNAL OF BOTANY 2022; 109:602-615. [PMID: 35067917 DOI: 10.1002/ajb2.1815] [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: 05/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
PREMISE Because of expected range shifts associated with climate change, there is a renewed interest in the evolutionary factors constraining adaptation, among which are genetic bottlenecks, drift, and increased mutational load after range expansion. Here we study adaptation in the short-lived species Leontodon longirostris showing reduced genetic diversity and increased genetic load along an expansion route. METHODS We assessed the phenological patterns of variation, and their effect on fitness-related traits, on 42 L. longirostris populations and six populations of the sister taxa L. saxatilis in a common garden located within the current range of both species. The comparison among L. longirostris populations allowed us to test for genetic clines consistent with local adaptation, whereas the comparison between taxa provided evidence for common adaptive features at the species level. RESULTS We found significant within-species variability for most traits, as well as differences with its close relative L. saxatilis. In general, seeds from drier, warmer, and unpredictable habitats showed overall lower and more restricted conditions for germination, seedlings emerged later and plants flowered earlier. Consequently, genotypes from arid and unpredictable environments attained smaller reproductive sizes and allocated more biomass to reproduction. Flowering time had the strongest direct effect on total plant size, but seedling emergence also showed an important indirect effect. CONCLUSIONS Our results show the crucial role of phenological patterns in shaping adaptive clines for major life-history stage transitions. Furthermore, the genetic load observed in L. longirostris does not seem to preclude adaptation to the climatic variability encountered along the expansion route.
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Affiliation(s)
| | - Maria Mayol
- CREAF, Cerdanyola del Vallès 08193, Spain
- Univ. Autònoma Barcelona, Cerdanyola del Vallès 08193, Spain
| | | | | | - Miquel Riba
- CREAF, Cerdanyola del Vallès 08193, Spain
- Univ. Autònoma Barcelona, Cerdanyola del Vallès 08193, Spain
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Fifer JE, Yasuda N, Yamakita T, Bove CB, Davies SW. Genetic divergence and range expansion in a western North Pacific coral. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 813:152423. [PMID: 34942242 DOI: 10.1016/j.scitotenv.2021.152423] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 06/14/2023]
Abstract
Coral poleward range expansions have recently been observed in response to warming oceans. Range expansion can lead to reduced genetic diversity and increased frequency of deleterious mutations that were rare in core populations, potentially limiting the ability for adaptation and persistence in novel environments. Successful expansions that overcome these founder effects and colonize new habitat have been attributed to multiple introductions from different sources, hybridization with native populations, or rapid adaptive evolution. Here, we investigate population genomic patterns of the reef-building coral Acropora hyacinthus along a latitudinal cline that includes a well-established range expansion front in Japan using 2b-RAD sequencing. A total of 184 coral samples were collected across seven sites spanning from ~24°N to near its northern range front at ~33°N. We uncover the presence of three cryptic lineages of A. hyacinthus, which occupy discrete reefs within this region. Only one lineage is present along the expansion front and we find evidence for its historical occupation of marginal habitats. Within this lineage we also find evidence of bottleneck pressures associated with expansion events including higher clonality, increased linkage disequilibrium, and lower genetic diversity in range edge populations compared to core populations. Asymmetric migration between populations was also detected with lower migration from edge sites. Lastly, we describe genomic signatures of local adaptation potentially attributed to lower winter temperatures experienced at the more recently expanded northern populations. Together these data illuminate the genomic consequences of range expansion in a coral and highlight how adaptation to discrete environments along expansion fronts may facilitate further range expansion in this temperate coral lineage.
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Affiliation(s)
- James E Fifer
- Department of Biology, Boston University, Boston, MA 02215, USA.
| | - Nina Yasuda
- Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadainishi, Miyazaki 889-2192, Japan.
| | - Takehisa Yamakita
- Marine Biodiversity and Environmental Assessment Research Center, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushimacho, Yokosuka, Kanagawa 237-0061, Japan
| | - Colleen B Bove
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Sarah W Davies
- Department of Biology, Boston University, Boston, MA 02215, USA
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35
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Gilbert KJ, Moinet A, Peischl S. Gene surfing of underdominant alleles promotes formation of hybrid zones. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210006. [PMID: 35067089 PMCID: PMC8784928 DOI: 10.1098/rstb.2021.0006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 07/28/2021] [Indexed: 11/12/2022] Open
Abstract
The distribution of genetic diversity over geographical space has long been investigated in population genetics and serves as a useful tool to understand evolution and history of populations. Within some species or across regions of contact between two species, there are instances where there is no apparent ecological determinant of sharp changes in allele frequencies or divergence. To further understand these patterns of spatial genetic structure and potential species divergence, we model the establishment of clines that occur due to the surfing of underdominant alleles during range expansions. We provide analytical approximations for the fixation probability of underdominant alleles at expansion fronts and demonstrate that gene surfing can lead to clines in one-dimensional range expansions. We extend these results to multiple loci via a mixture of analytical theory and individual-based simulations. We study the interaction between the strength of selection against heterozygotes, migration rates, and local recombination rates on the formation of stable hybrid zones. Clines created by surfing at different loci can attract each other and align after expansion, if they are sufficiently close in space and in terms of recombination distance. Our findings suggest that range expansions can set the stage for parapatric speciation due to the alignment of multiple selective clines, even in the absence of ecologically divergent selection. This article is part of the theme issue 'Species' ranges in the face of changing environments (part I)'.
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Affiliation(s)
- Kimberly J. Gilbert
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, Bern 3013, Switzerland
| | - Antoine Moinet
- Interfaculty Bioinformatics Unit, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
- Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
- Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland
| | - Stephan Peischl
- Interfaculty Bioinformatics Unit, University of Bern, Baltzerstrasse 6, Bern 3012, Switzerland
- Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland
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36
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MacPherson A, Wang S, Yamaguchi R, Rieseberg L, Otto S. Parental Population Range Expansion Before Secondary Contact Promotes Heterosis. Am Nat 2022; 200:E1-E15. [DOI: 10.1086/719656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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37
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Moinet A, Schlichta F, Peischl S, Excoffier L. Strong neutral sweeps occurring during a population contraction. Genetics 2022; 220:6529544. [PMID: 35171980 PMCID: PMC8982045 DOI: 10.1093/genetics/iyac021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 01/22/2022] [Indexed: 11/14/2022] Open
Abstract
A strong reduction in diversity around a specific locus is often interpreted as a recent rapid fixation of a positively selected allele, a phenomenon called a selective sweep. Rapid fixation of neutral variants can however lead to a similar reduction in local diversity, especially when the population experiences changes in population size, e.g. bottlenecks or range expansions. The fact that demographic processes can lead to signals of nucleotide diversity very similar to signals of selective sweeps is at the core of an ongoing discussion about the roles of demography and natural selection in shaping patterns of neutral variation. Here, we quantitatively investigate the shape of such neutral valleys of diversity under a simple model of a single population size change, and we compare it to signals of a selective sweep. We analytically describe the expected shape of such "neutral sweeps" and show that selective sweep valleys of diversity are, for the same fixation time, wider than neutral valleys. On the other hand, it is always possible to parametrize our model to find a neutral valley that has the same width as a given selected valley. Our findings provide further insight into how simple demographic models can create valleys of genetic diversity similar to those attributed to positive selection.
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Affiliation(s)
- Antoine Moinet
- Interfaculty Bioinformatics Unit, University of Bern, Bern 3012, Switzerland,Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland,Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Flávia Schlichta
- Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland,Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Stephan Peischl
- Interfaculty Bioinformatics Unit, University of Bern, Bern 3012, Switzerland,Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland,Corresponding author.
| | - Laurent Excoffier
- Swiss Institute of Bioinformatics, Lausanne 1015, Switzerland,Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
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38
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Lindstedt C, Bagley R, Calhim S, Jones M, Linnen C. The impact of life stage and pigment source on the evolution of novel warning signal traits. Evolution 2022; 76:554-572. [PMID: 35103303 PMCID: PMC9304160 DOI: 10.1111/evo.14443] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 12/06/2021] [Indexed: 11/28/2022]
Abstract
Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency‐dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet‐based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine‐feeding hymenopteran. Although our experiments confirm that N. lecontei larvae are indeed aposematic—and therefore likely to experience frequency‐dependent predation—our genomic data do not support a historical demographic scenario that would have facilitated the spread of an initially deleterious allele via drift. Additionally, significantly elevated differentiation at a known color locus suggests that geographic variation in larval color is currently maintained by selection. Together, these data suggest that the novel white morph likely spread via selection. However, white body color does not enhance aposematic displays, nor is it correlated with enhanced chemical defense or immune function. Instead, the derived white‐bodied morph is disproportionately abundant on a pine species with a reduced carotenoid content relative to other pine hosts, suggesting that bottom‐up selection via host plants may have driven divergence among populations. Overall, our results suggest that life stage and pigment source can have a substantial impact on the evolution of novel warning signals, highlighting the need to investigate diverse aposematic taxa to develop a comprehensive understanding of color variation in nature.
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Affiliation(s)
- Carita Lindstedt
- Department of Biological and Environmental Sciences, University of Jyväskylä, Finland
| | - Robin Bagley
- Department of Biology, University of Kentucky, Lexington, Kentucky, 40506, USA.,Department of Evolution, Ecology, and Organismal Biology, The Ohio State University at Lima, Lima, OH, 45804, USA
| | - Sara Calhim
- Department of Biological and Environmental Sciences, University of Jyväskylä, Finland
| | - Mackenzie Jones
- Department of Biology, University of Kentucky, Lexington, Kentucky, 40506, USA
| | - Catherine Linnen
- Department of Biology, University of Kentucky, Lexington, Kentucky, 40506, USA
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39
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Forni D, Cagliani R, Pontremoli C, Clerici M, Sironi M. The substitution spectra of coronavirus genomes. Brief Bioinform 2022; 23:bbab382. [PMID: 34518866 PMCID: PMC8499949 DOI: 10.1093/bib/bbab382] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 12/23/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has triggered an unprecedented international effort to sequence complete viral genomes. We leveraged this wealth of information to characterize the substitution spectrum of SARS-CoV-2 and to compare it with those of other human and animal coronaviruses. We show that, once nucleotide composition is taken into account, human and most animal coronaviruses display a mutation spectrum dominated by C to U and G to U substitutions, a feature that is not shared by other positive-sense RNA viruses. However, the proportions of C to U and G to U substitutions tend to decrease as divergence increases, suggesting that, whatever their origin, a proportion of these changes is subsequently eliminated by purifying selection. Analysis of the sequence context of C to U substitutions showed little evidence of apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC)-mediated editing and such contexts were similar for SARS-CoV-2 and Middle East respiratory syndrome coronavirus sampled from different hosts, despite different repertoires of APOBEC3 proteins in distinct species. Conversely, we found evidence that C to U and G to U changes affect CpG dinucleotides at a frequency higher than expected. Whereas this suggests ongoing selective reduction of CpGs, this effect alone cannot account for the substitution spectra. Finally, we show that, during the first months of SARS-CoV-2 pandemic spread, the frequency of both G to U and C to U substitutions increased. Our data suggest that the substitution spectrum of SARS-CoV-2 is determined by an interplay of factors, including intrinsic biases of the replication process, avoidance of CpG dinucleotides and other constraints exerted by the new host.
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Affiliation(s)
- Diego Forni
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Rachele Cagliani
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Chiara Pontremoli
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, Milan, Italy
- Don C. Gnocchi Foundation ONLUS, IRCCS, Milan, Italy
| | - Manuela Sironi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
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40
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Vecchyo DOD, Lohmueller KE, Novembre J. Haplotype-based inference of the distribution of fitness effects. Genetics 2022; 220:6501446. [PMID: 35100400 PMCID: PMC8982047 DOI: 10.1093/genetics/iyac002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/18/2021] [Indexed: 11/13/2022] Open
Abstract
Abstract
Recent genome sequencing studies with large sample sizes in humans have discovered a vast quantity of low-frequency variants, providing an important source of information to analyze how selection is acting on human genetic variation. In order to estimate the strength of natural selection acting on low-frequency variants, we have developed a likelihood-based method that uses the lengths of pairwise identity-by-state between haplotypes carrying low-frequency variants. We show that in some non-equilibrium populations (such as those that have had recent population expansions) it is possible to distinguish between positive or negative selection acting on a set of variants. With our new framework, one can infer a fixed selection intensity acting on a set of variants at a particular frequency, or a distribution of selection coefficients for standing variants and new mutations. We show an application of our method to the UK10K phased haplotype dataset of individuals.
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Affiliation(s)
- Diego Ortega-Del Vecchyo
- Laboratorio Internacional de Investigación sobre el Genoma Humano, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, 76230, México
- Interdepartmental Program in Bioinformatics, University of California, Los Angeles, Los Angeles, California, 90095, United States of America
| | - Kirk E Lohmueller
- Interdepartmental Program in Bioinformatics, University of California, Los Angeles, Los Angeles, California, 90095, United States of America
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, 90095, United States of America
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, 90095, United States of America
| | - John Novembre
- Department of Human Genetics, University of Chicago, Chicago, Illinois, 60637, United States of America
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, 60637, United States of America
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41
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Shirsekar G, Devos J, Latorre SM, Blaha A, Queiroz Dias M, González Hernando A, Lundberg DS, Burbano HA, Fenster CB, Weigel D. Multiple Sources of Introduction of North American Arabidopsis thaliana from across Eurasia. Mol Biol Evol 2021; 38:5328-5344. [PMID: 34499163 PMCID: PMC8662644 DOI: 10.1093/molbev/msab268] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Large-scale movement of organisms across their habitable range, or migration, is an important evolutionary process that can shape genetic diversity and influence the adaptive spread of alleles. Although human migrations have been studied in great detail with modern and ancient genomes, recent anthropogenic influence on reducing the biogeographical constraints on the migration of nonnative species has presented opportunities in several study systems to ask the questions about how repeated introductions shape genetic diversity in the introduced range. We present an extensive overview of population structure of North American Arabidopsis thaliana by studying a set of 500 whole-genome sequenced and over 2,800 RAD-seq genotyped individuals in the context of global diversity represented by Afro-Eurasian genomes. We use methods based on haplotype and rare-allele sharing as well as phylogenetic modeling to identify likely sources of introductions of extant N. American A. thaliana from the native range in Africa and Eurasia. We find evidence of admixture among the introduced lineages having increased haplotype diversity and reduced mutational load. We also detect signals of selection in immune-system-related genes that may impart qualitative disease resistance to pathogens of bacterial and oomycete origin. We conclude that multiple introductions to a nonnative range can rapidly enhance the adaptive potential of a colonizing species by increasing haplotypic diversity through admixture. Our results lay the foundation for further investigations into the functional significance of admixture.
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Affiliation(s)
- Gautam Shirsekar
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Jane Devos
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Sergio M Latorre
- Max Planck Institute for Developmental Biology, Tübingen, Germany
- Centre for Life’s Origin and Evolution, University College London, London, United Kingdom
| | - Andreas Blaha
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | | | | | - Derek S Lundberg
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Hernán A Burbano
- Max Planck Institute for Developmental Biology, Tübingen, Germany
- Centre for Life’s Origin and Evolution, University College London, London, United Kingdom
| | - Charles B Fenster
- Oak Lake Field Station, Department of Natural Resource Management, South Dakota State University, Brookings, SD, USA
| | - Detlef Weigel
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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42
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Ackiss AS, Magee MR, Sass GG, Turnquist K, McIntyre PB, Larson WA. Genomic and environmental influences on resilience in a cold-water fish near the edge of its range. Evol Appl 2021; 14:2794-2814. [PMID: 34950230 PMCID: PMC8674893 DOI: 10.1111/eva.13313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 10/05/2021] [Accepted: 10/07/2021] [Indexed: 02/06/2023] Open
Abstract
Small, isolated populations present a challenge for conservation. The dueling effects of selection and drift in a limited pool of genetic diversity make the responses of small populations to environmental perturbations erratic and difficult to predict. This is particularly true at the edge of a species range, where populations often persist at the limits of their environmental tolerances. Populations of cisco, Coregonus artedi, in inland lakes have experienced numerous extirpations along the southern edge of their range in recent decades, which are thought to result from environmental degradation and loss of cold, well-oxygenated habitat as lakes warm. Yet, cisco extirpations do not show a clear latitudinal pattern, suggesting that local environmental factors and potentially local adaptation may influence resilience. Here, we used genomic tools to investigate the nature of this pattern of resilience. We used restriction site-associated DNA capture (Rapture) sequencing to survey genomic diversity and differentiation in southern inland lake cisco populations and compared the frequency of deleterious mutations that potentially influence fitness across lakes. We also examined haplotype diversity in a region of the major histocompatibility complex involved in stress and immune system response. We correlated these metrics to spatial and environmental factors including latitude, lake size, and measures of oxythermal habitat and found significant relationships between genetic metrics and broad and local factors. High levels of genetic differentiation among populations were punctuated by a phylogeographic break and residual patterns of isolation-by-distance. Although the prevalence of deleterious mutations and inbreeding coefficients was significantly correlated with latitude, neutral and non-neutral genetic diversity were most strongly correlated with lake surface area. Notably, differences among lakes in the availability of estimated oxythermal habitat left no clear population genomic signature. Our results shed light on the complex dynamics influencing these isolated populations and provide valuable information for their conservation.
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Affiliation(s)
- Amanda S. Ackiss
- Wisconsin Cooperative Fishery Research UnitCollege of Natural ResourcesUniversity of Wisconsin‐Stevens PointStevens PointWisconsinUSA
- U.S. Geological SurveyGreat Lakes Science CenterAnn ArborMichiganUSA
| | | | - Greg G. Sass
- Escanaba Lake Research StationWisconsin Department of Natural ResourcesBoulder JunctionWisconsinUSA
| | - Keith Turnquist
- Wisconsin Cooperative Fishery Research UnitCollege of Natural ResourcesUniversity of Wisconsin‐Stevens PointStevens PointWisconsinUSA
| | - Peter B. McIntyre
- Department of Natural Resources and the EnvironmentCornell UniversityIthacaNew YorkUSA
| | - Wesley A. Larson
- U.S. Geological SurveyWisconsin Cooperative Fishery Research UnitCollege of Natural ResourcesUniversity of Wisconsin‐Stevens PointStevens PointWisconsinUSA
- National Oceanographic and Atmospheric AdministrationNational Marine Fisheries ServiceAlaska Fisheries Science CenterAuke Bay LaboratoriesJuneauAlaskaUSA
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43
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Sohail M, Izarraras-Gomez A, Ortega-Del Vecchyo D. Populations, Traits, and Their Spatial Structure in Humans. Genome Biol Evol 2021; 13:evab272. [PMID: 34894236 PMCID: PMC8715524 DOI: 10.1093/gbe/evab272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2021] [Indexed: 11/16/2022] Open
Abstract
The spatial distribution of genetic variants is jointly determined by geography, past demographic processes, natural selection, and its interplay with environmental variation. A fraction of these genetic variants are "causal alleles" that affect the manifestation of a complex trait. The effect exerted by these causal alleles on complex traits can be independent or dependent on the environment. Understanding the evolutionary processes that shape the spatial structure of causal alleles is key to comprehend the spatial distribution of complex traits. Natural selection, past population size changes, range expansions, consanguinity, assortative mating, archaic introgression, admixture, and the environment can alter the frequencies, effect sizes, and heterozygosities of causal alleles. This provides a genetic axis along which complex traits can vary. However, complex traits also vary along biogeographical and sociocultural axes which are often correlated with genetic axes in complex ways. The purpose of this review is to consider these genetic and environmental axes in concert and examine the ways they can help us decipher the variation in complex traits that is visible in humans today. This initiative necessarily implies a discussion of populations, traits, the ability to infer and interpret "genetic" components of complex traits, and how these have been impacted by adaptive events. In this review, we provide a history-aware discussion on these topics using both the recent and more distant past of our academic discipline and its relevant contexts.
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Affiliation(s)
- Mashaal Sohail
- Department of Human Genetics, University of Chicago, USA
- Centro de Ciencias Genómicas (CCG), Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, México
| | - Alan Izarraras-Gomez
- Laboratorio Internacional de Investigación sobre el Genoma Humano (LIIGH), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, México
| | - Diego Ortega-Del Vecchyo
- Laboratorio Internacional de Investigación sobre el Genoma Humano (LIIGH), Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro, México
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44
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North HL, McGaughran A, Jiggins CD. Insights into invasive species from whole-genome resequencing. Mol Ecol 2021; 30:6289-6308. [PMID: 34041794 DOI: 10.1111/mec.15999] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/12/2021] [Accepted: 04/30/2021] [Indexed: 12/12/2022]
Abstract
Studies of invasive species can simultaneously inform management strategies and quantify rapid evolution in the wild. The role of genomics in invasion science is increasingly recognised, and the growing availability of reference genomes for invasive species is paving the way for whole-genome resequencing studies in a wide range of systems. Here, we survey the literature to assess the application of whole-genome resequencing data in invasion biology. For some applications, such as the reconstruction of invasion routes in time and space, sequencing the whole genome of many individuals can increase the accuracy of existing methods. In other cases, population genomic approaches such as haplotype analysis can permit entirely new questions to be addressed and new technologies applied. To date whole-genome resequencing has only been used in a handful of invasive systems, but these studies have confirmed the importance of processes such as balancing selection and hybridization in allowing invasive species to reuse existing adaptations and rapidly overcome the challenges of a foreign ecosystem. The use of genomic data does not constitute a paradigm shift per se, but by leveraging new theory, tools, and technologies, population genomics can provide unprecedented insight into basic and applied aspects of invasion science.
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Affiliation(s)
- Henry L North
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Angela McGaughran
- Te Aka Mātuatua/School of Science, University of Waikato, Hamilton, New Zealand
| | - Chris D Jiggins
- Department of Zoology, University of Cambridge, Cambridge, UK
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45
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Capblancq T, Munson H, Butnor JR, Keller SR. Genomic drivers of early-life fitness in Picea rubens. CONSERV GENET 2021. [DOI: 10.1007/s10592-021-01378-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Bontrager M, Usui T, Lee-Yaw JA, Anstett DN, Branch HA, Hargreaves AL, Muir CD, Angert AL. Adaptation across geographic ranges is consistent with strong selection in marginal climates and legacies of range expansion. Evolution 2021; 75:1316-1333. [PMID: 33885152 DOI: 10.1111/evo.14231] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/14/2021] [Indexed: 12/27/2022]
Abstract
Every species experiences limits to its geographic distribution. Some evolutionary models predict that populations at range edges are less well adapted to their local environments due to drift, expansion load, or swamping gene flow from the range interior. Alternatively, populations near range edges might be uniquely adapted to marginal environments. In this study, we use a database of transplant studies that quantify performance at broad geographic scales to test how local adaptation, site quality, and population quality change from spatial and climatic range centers toward edges. We find that populations from poleward edges perform relatively poorly, both on average across all sites (15% lower population quality) and when compared to other populations at home (31% relative fitness disadvantage), consistent with these populations harboring high genetic load. Populations from equatorial edges also perform poorly on average (18% lower population quality) but, in contrast, outperform foreign populations (16% relative fitness advantage), suggesting that populations from equatorial edges have strongly adapted to unique environments. Finally, we find that populations from sites that are thermally extreme relative to the species' niche demonstrate strong local adaptation, regardless of their geographic position. Our findings indicate that both nonadaptive processes and adaptive evolution contribute to variation in adaptation across species' ranges.
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Affiliation(s)
- Megan Bontrager
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada.,Current Address: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Takuji Usui
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada
| | - Julie A Lee-Yaw
- Department of Biological Sciences, University of Lethbridge, Lethbridge, T1K 3M4, Canada
| | - Daniel N Anstett
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada
| | - Haley A Branch
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada
| | | | - Christopher D Muir
- School of Life Sciences, University of Hawaii, Honolulu, Hawaii, 96822, United States
| | - Amy L Angert
- Departments of Botany and Zoology and the Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada
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47
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Takou M, Hämälä T, Koch EM, Steige KA, Dittberner H, Yant L, Genete M, Sunyaev S, Castric V, Vekemans X, Savolainen O, de Meaux J. Maintenance of Adaptive Dynamics and No Detectable Load in a Range-Edge Outcrossing Plant Population. Mol Biol Evol 2021; 38:1820-1836. [PMID: 33480994 PMCID: PMC8097302 DOI: 10.1093/molbev/msaa322] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During range expansion, edge populations are expected to face increased genetic drift, which in turn can alter and potentially compromise adaptive dynamics, preventing the removal of deleterious mutations and slowing down adaptation. Here, we contrast populations of the European subspecies Arabidopsis lyrata ssp. petraea, which expanded its Northern range after the last glaciation. We document a sharp decline in effective population size in the range-edge population and observe that nonsynonymous variants segregate at higher frequencies. We detect a 4.9% excess of derived nonsynonymous variants per individual in the range-edge population, suggesting an increase of the genomic burden of deleterious mutations. Inference of the fitness effects of mutations and modeling of allele frequencies under the explicit demographic history of each population predicts a depletion of rare deleterious variants in the range-edge population, but an enrichment for fixed ones, consistent with the bottleneck effect. However, the demographic history of the range-edge population predicts a small net decrease in per-individual fitness. Consistent with this prediction, the range-edge population is not impaired in its growth and survival measured in a common garden experiment. We further observe that the allelic diversity at the self-incompatibility locus, which ensures strict outcrossing and evolves under negative frequency-dependent selection, has remained unchanged. Genomic footprints indicative of selective sweeps are broader in the Northern population but not less frequent. We conclude that the outcrossing species A. lyrata ssp. petraea shows a strong resilience to the effect of range expansion.
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Affiliation(s)
- Margarita Takou
- Institute of Botany, University of Cologne, Cologne, Germany
| | - Tuomas Hämälä
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, USA
| | - Evan M Koch
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Kim A Steige
- Institute of Botany, University of Cologne, Cologne, Germany
| | | | - Levi Yant
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Mathieu Genete
- CNRS, UMR 8198 – Evo-Eco-Paleo, University of Lille, Lille, France
| | - Shamil Sunyaev
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Vincent Castric
- CNRS, UMR 8198 – Evo-Eco-Paleo, University of Lille, Lille, France
| | - Xavier Vekemans
- CNRS, UMR 8198 – Evo-Eco-Paleo, University of Lille, Lille, France
| | - Outi Savolainen
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
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48
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VanWallendael A, Alvarez M, Franks SJ. Patterns of population genomic diversity in the invasive Japanese knotweed species complex. AMERICAN JOURNAL OF BOTANY 2021; 108:857-868. [PMID: 33942283 DOI: 10.1002/ajb2.1653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
PREMISE Invasive species are expected to undergo a reduction in genetic diversity due to founder effects, which should limit their ability to adapt to new habitats. Still, many invasive species achieve widespread distributions and dense populations. This paradox of invasions could potentially be overcome through multiple introductions or hybridization, both of which increase genetic diversity. We conducted a population genomics study of Japanese knotweed (Reynoutria japonica), which is a polyploid, clonally reproducing invasive species that has been notoriously successful worldwide despite supposedly low genetic diversity. METHODS We used genotyping by sequencing to collect 12,912 SNP markers from 88 samples collected at 38 locations across North America for the species complex. We used alignment-free k-mer hashing analysis in addition to traditional population genetic analyses to account for the challenges of genotyping polyploids. RESULTS Genotypes conformed to three genetic clusters, likely representing Japanese knotweed, giant knotweed, and hybrid bohemian knotweed. We found that, contrary to previous findings, the Japanese knotweed cluster had substantial genetic diversity, though it had no apparent genetic structure across the landscape. In contrast, giant knotweed and hybrids showed distinct population groups. We did not find evidence of isolation by distance in the species complex, likely reflecting the stochastic introduction history of this species complex. CONCLUSIONS The results indicate that clonal invasive species can show substantial genetic diversity and can be successful at colonizing a variety of habitats without showing evidence of local adaptation or genetic structure.
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Affiliation(s)
- Acer VanWallendael
- Biology Department, Fordham University, 441 E. Fordham Road, Bronx, NY, 10458, USA
- Biology Department, Duke University, 130 Science Drive, Durham, NC, 27708, USA
| | - Mariano Alvarez
- Biology Department, Duke University, 130 Science Drive, Durham, NC, 27708, USA
| | - Steven J Franks
- Biology Department, Fordham University, 441 E. Fordham Road, Bronx, NY, 10458, USA
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Eriksson M, Rafajlović M. The Effect of the Recombination Rate between Adaptive Loci on the Capacity of a Population to Expand Its Range. Am Nat 2021; 197:526-542. [PMID: 33908832 DOI: 10.1086/713669] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractPrevious theoretical work on range expansions over heterogeneous environments showed that there is a critical environmental gradient where range expansion stops. For populations with freely recombining loci underlying the trait under selection (hereafter, "adaptive loci"), the critical gradient in one-dimensional habitats depends on the fitness cost of dispersal and the strength of selection relative to genetic drift. Here, we extend the previous work in two directions and ask, What is the role of the recombination rate between the adaptive loci during range expansions? And what effect does the ability of selfing as opposed to obligate outcrossing have on range expansions? To answer these questions, we use computer simulations. We demonstrate that while reduced recombination rates between adaptive loci slow down range expansions as a result of poor purging of locally deleterious alleles at the expansion front, they may also allow a species to occupy a greater range. In addition, we find that the allowance of selfing may improve the ability of populations to expand their ranges, for example, because selfing among potentially rare high-fitness individuals facilitates the establishment and maintenance of locally well-adapted genotypes. We conclude that during range expansions there is a trade-off between positive and negative effects of recombination within and between individuals.
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Pflugbeil G, Affenzeller M, Tribsch A, Comes HP. Primary hybrid zone formation in Tephroseris helenitis (Asteraceae), following postglacial range expansion along the central Northern Alps. Mol Ecol 2021; 30:1704-1720. [PMID: 33548078 PMCID: PMC8048512 DOI: 10.1111/mec.15832] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 11/26/2022]
Abstract
Distinguishing between secondary versus primary hybrid zone formation remains a challenging task as, for instance, the time window in which these historical (vicariant) versus contemporary (environmental-selective) processes are distinguishable may be relatively narrow. Here, we examine the origin and structure of a transition zone between two subspecies of Tephroseris helenitis along the central Northern Alps, using molecular (AFLP) and morphological (achene type) data in combination with ecological niche models (ENMs) to hindcast ranges at the Last Glacial Maximum (LGM) and mid-Holocene. Samples were collected over a c. 350 km long transect, largely covered by ice during the LGM. Genetically nonadmixed individuals of subspp. helenitis versus salisburgensis dominated the westernmost versus eastern transect areas, with admixed individuals occurring in between. Clines for achene morphology and outlier loci potentially under climate-driven selection were steep, largely noncoincidental, and displaced to the east of the cline centre for neutral AFLPs. During the LGM, ssp. helenitis should have been able to persist in a refugium southwest of the transect, while suitable habitat for ssp. salisburgensis was apparently absent at this time. Together with patterns of genetic and clinal variation, our ENM data are suggestive of a primary hybrid zone that originated after the species' postglacial, eastward expansion. The observed clinal changes may thus reflect random/nonadaptive processes during expansion and selection on particular loci, and possibly achene type, in response to a long-term, west-to-east climate gradient in the direction of more stressful (e.g., wetter/cooler) conditions. Overall, this study adds to the vast hybrid zone literature a rare example of a hybrid zone caused by primary differentiation within a plant species, underlaid by historical range expansion.
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Affiliation(s)
- Georg Pflugbeil
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | | | - Andreas Tribsch
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Hans Peter Comes
- Department of Biosciences, University of Salzburg, Salzburg, Austria
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