1
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Quilodrán CS, Currat M, Montoya-Burgos JI. Benchmarking the Mantel test and derived methods for testing association between distance matrices. Mol Ecol Resour 2023. [PMID: 38041538 DOI: 10.1111/1755-0998.13898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 10/12/2023] [Accepted: 10/30/2023] [Indexed: 12/03/2023]
Abstract
Testing the association between objects is central in ecology, evolution, and quantitative sciences in general. Two types of variables can describe the relationships between objects: point variables (measured on individual objects), and distance variables (measured between pairs of objects). The Mantel test and derived methods have been extensively used for distance variables. Yet, these methods have been criticized due to low statistical power and inflated type I error when spatial autocorrelation is present. Here, we assessed the statistical power between different types of tested variables and the type I error rate over a wider range of autocorrelation intensities than previously assessed, both on univariate and multivariate data. We also illustrated the performance of distance matrix statistics through computational simulations of genetic diversity. We show that the Mantel test and derived methods are not affected by inflated type I error when spatial autocorrelation affects only one variable when investigating correlations, or when either the response or the explanatory variable(s) is affected by spatial autocorrelation while investigating causal relationships. As previously noted, with autocorrelation affecting more variables, inflated type I error could be reduced by modifying the significance threshold. Additionally, the Mantel test has no problem of statistical power when the hypothesis is formulated in terms of distance variables. We highlight that transformation of variable types should be avoided because of the potential information loss and modification of the tested hypothesis. We propose a set of guidelines to help choose the appropriate method according to the type of variables and defined hypothesis.
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Affiliation(s)
- Claudio S Quilodrán
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Mathias Currat
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (IGE3), University of Geneva, Geneva, Switzerland
| | - Juan I Montoya-Burgos
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (IGE3), University of Geneva, Geneva, Switzerland
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2
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Di Santo LN, Quilodrán CS, Currat M. Temporal Variation in Introgressed Segments' Length Statistics Computed from a Limited Number of Ancient Genomes Sheds Light on Past Admixture Pulses. Mol Biol Evol 2023; 40:msad252. [PMID: 37992125 PMCID: PMC10715198 DOI: 10.1093/molbev/msad252] [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: 04/18/2023] [Revised: 10/16/2023] [Accepted: 11/09/2023] [Indexed: 11/24/2023] Open
Abstract
Hybridization is recognized as an important evolutionary force, but identifying and timing admixture events between divergent lineages remain a major aim of evolutionary biology. While this has traditionally been done using inferential tools on contemporary genomes, the latest advances in paleogenomics have provided a growing wealth of temporally distributed genomic data. Here, we used individual-based simulations to generate chromosome-level genomic data for a 2-population system and described temporal neutral introgression patterns under a single- and 2-pulse admixture model. We computed 6 summary statistics aiming to inform the timing and number of admixture pulses between interbreeding entities: lengths of introgressed sequences and their variance within genomes, as well as genome-wide introgression proportions and related measures. The first 2 statistics could confidently be used to infer interlineage hybridization history, peaking at the beginning and shortly after an admixture pulse. Temporal variation in introgression proportions and related statistics provided more limited insights, particularly when considering their application to ancient genomes still scant in number. Lastly, we computed these statistics on Homo sapiens paleogenomes and successfully inferred the hybridization pulse from Neanderthal that occurred approximately 40 to 60 kya. The scarce number of genomes dating from this period prevented more precise inferences, but the accumulation of paleogenomic data opens promising perspectives as our approach only requires a limited number of ancient genomes.
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Affiliation(s)
- Lionel N Di Santo
- Department of Genetics and Evolution, University of Geneva, Geneva CH-1205
| | | | - Mathias Currat
- Department of Genetics and Evolution, University of Geneva, Geneva CH-1205
- Institute of Genetics and Genomics in Geneva (IGE3), University of Geneva, Geneva CH-1205
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3
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Anderson SAS, López-Fernández H, Weir JT. Ecology and the origin of non-ephemeral species. Am Nat 2022; 201:619-638. [PMID: 37130236 DOI: 10.1086/723763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractResearch over the past three decades has shown that ecology-based extrinsic reproductive barriers can rapidly arise to generate incipient species-but such barriers can also rapidly dissolve when environments change, resulting in incipient species collapse. Understanding the evolution of unconditional, "intrinsic" reproductive barriers is therefore important for understanding the longer-term buildup of biodiversity. In this article, we consider ecology's role in the evolution of intrinsic reproductive isolation. We suggest that this topic has fallen into a gap between disciplines: while evolutionary ecologists have traditionally focused on the rapid evolution of extrinsic isolation between co-occurring ecotypes, speciation geneticists studying intrinsic isolation in other taxa have devoted little attention to the ecological context in which it evolves. We argue that for evolutionary ecology to close this gap, the field will have to expand its focus beyond rapid adaptation and its traditional model systems. Synthesizing data from several subfields, we present circumstantial evidence for and against different forms of ecological adaptation as promoters of intrinsic isolation and discuss alternative forces that may be significant. We conclude by outlining complementary approaches that can better address the role of ecology in the evolution of nonephemeral reproductive barriers and, by extension, less ephemeral species.
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4
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Hollenbeck CM, Portnoy DS, Garcia de la Serrana D, Magnesen T, Matejusova I, Johnston IA. Temperature-associated selection linked to putative chromosomal inversions in king scallop ( Pecten maximus). Proc Biol Sci 2022; 289:20221573. [PMID: 36196545 PMCID: PMC9532988 DOI: 10.1098/rspb.2022.1573] [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: 11/27/2022] Open
Abstract
The genomic landscape of divergence—the distribution of differences among populations or species across the genome—is increasingly characterized to understand the role that microevolutionary forces such as natural selection and recombination play in causing and maintaining genetic divergence. This line of inquiry has also revealed chromosome structure variation to be an important factor shaping the landscape of adaptive genetic variation. Owing to a high prevalence of chromosome structure variation and the strong pressure for local adaptation necessitated by their sessile nature, bivalve molluscs are an ideal taxon for exploring the relationship between chromosome structure variation and local adaptation. Here, we report a population genomic survey of king scallop (Pecten maximus) across its natural range in the northeastern Atlantic Ocean, using a recent chromosome-level genome assembly. We report the presence of at least three large (12–22 Mb), putative chromosomal inversions associated with sea surface temperature and whose frequencies are in contrast to neutral population structure. These results highlight a potentially large role for recombination-suppressing chromosomal inversions in local adaptation and suggest a hypothesis to explain the maintenance of differences in reproductive timing found at relatively small spatial scales across king scallop populations.
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Affiliation(s)
- Christopher M Hollenbeck
- Department of Life Sciences, Texas A&M University Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA.,Texas A&M AgriLife Research, College Station, TX, USA
| | - David S Portnoy
- Department of Life Sciences, Texas A&M University Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Daniel Garcia de la Serrana
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Thorolf Magnesen
- Department of Biological Sciences, University of Bergen, Thormøhlensgt 53B, Bergen, Norway
| | - Iveta Matejusova
- Marine Science Scotland, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - Ian A Johnston
- Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, UK.,Xelect Ltd, Horizon House, Abbey Walk, St Andrews KY16 9LB, UK
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5
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Fontúrbel FE, Rodríguez-Gómez GB, Orellana JI, Cortés-Miranda J, Rojas-Hernández N, Vega-Retter C. Geographical context outweighs habitat disturbance effects in explaining mistletoe population genetic differentiation at a regional scale. Mol Ecol 2022; 31:1389-1402. [PMID: 34995392 DOI: 10.1111/mec.16337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 11/03/2021] [Accepted: 12/17/2021] [Indexed: 11/29/2022]
Abstract
Genetic differentiation depends on ecological and evolutionary processes that operate at different spatial and temporal scales. While the geographical context is likely to determine large-scale genetic variation patterns, habitat disturbance events will probably influence small-scale genetic diversity and gene flow patterns. Therefore, the genetic diversity patterns that we observe today result from the combination of both processes, but they are rarely assessed simultaneously. We determined the population structure and genetic diversity of a hemiparasitic mistletoe (Tristerix corymbosus) from the temperate rainforests of southern Chile to determine the effects of geographical context and habitat disturbance at a regional scale and if it is affected by the abundance and occurrence of its seed disperser mutualist (the arboreal marsupial Dromiciops gliroides). We genotyped 359 individuals from 12 populations using single nucleotide polymorphisms, across three different geographical contexts and four disturbance conditions. We also used camera traps to estimate the abundance and occurrence of the seed disperser. Our results suggest that genetic differences among populations are related more to geographical context than to habitat disturbance. However, as disturbance increased, D. gliroides abundance and occurrence decreased, and mistletoe inbreeding index (FIS ) increased. We also found highly uneven gene flow among study sites. Despite the high levels of disturbance that these temperate rainforests are facing, our results suggest that mistletoe genetic differentiation at a regional scale was more influenced by historical events. However, habitat disturbance can indirectly affect mistletoe population genetic differentiation via the seed dispersal process, which may increase levels of inbreeding.
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Affiliation(s)
- Francisco E Fontúrbel
- Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.,Millennium Nucleus of Patagonian Limit of Life (LiLi)
| | - Gloria B Rodríguez-Gómez
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - José I Orellana
- Laboratorio de Vida Silvestre, Universidad de Los Lagos, Osorno, Chile
| | - Jorge Cortés-Miranda
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Noemí Rojas-Hernández
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Caren Vega-Retter
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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6
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Crotti M, Bean CW, Gowans ARD, Winfield IJ, Butowska M, Wanzenböck J, Bondarencko G, Praebel K, Adams CE, Elmer KR. Complex and divergent histories gave rise to genome-wide divergence patterns amongst European whitefish (Coregonus lavaretus). J Evol Biol 2021; 34:1954-1969. [PMID: 34653264 PMCID: PMC9251650 DOI: 10.1111/jeb.13948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 10/01/2021] [Accepted: 10/08/2021] [Indexed: 12/31/2022]
Abstract
Pleistocene glaciations dramatically affected species distribution in regions that were impacted by ice cover and subsequent postglacial range expansion impacted contemporary biodiversity in complex ways. The European whitefish, Coregonus lavaretus, is a widely distributed salmonid fish species on mainland Europe, but in Britain it has only seven native populations, all of which are found on the western extremes of the island. The origins and colonization routes of the species into Britain are unknown but likely contributed to contemporary genetic patterns and regional uniqueness. Here, we used up to 25,751 genome‐wide polymorphic loci to reconstruct the history and to discern the demographic and evolutionary forces underpinning divergence between British populations. Overall, we found lower genetic diversity in Scottish populations but high differentiation (FST = 0.433–0.712) from the English/Welsh and other European populations. Differentiation was elevated genome‐wide rather than in particular genomic regions. Demographic modelling supported a postglacial colonization into western Scotland from northern refugia and a separate colonization route for the English/Welsh populations from southern refugia, with these two groups having been separated for more than ca. 50 Ky. We found cyto‐nuclear discordance at a European scale, with the Scottish populations clustering closely with Baltic population in the mtDNA analysis but not in the nuclear data, and with the Norwegian and Alpine populations displaying the same mtDNA haplotype but being distantly related in the nuclear tree. These findings suggest that neutral processes, primarily drift and regionally distinct pre‐glacial evolutionary histories, are important drivers of genomic divergence in British populations of European whitefish. This sheds new light on the establishment of the native British freshwater fauna after the last glacial maximum.
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Affiliation(s)
- Marco Crotti
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Colin W Bean
- Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Glasgow, UK.,NatureScot, Clydebank, UK
| | | | - Ian J Winfield
- Lake Ecosystems Group, UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, UK
| | - Magdalena Butowska
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Josef Wanzenböck
- Research Institute for Limnology, Mondsee, University of Innsbruck, Mondsee, Austria
| | | | - Kim Praebel
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Colin E Adams
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK.,Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Glasgow, UK
| | - Kathryn R Elmer
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
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7
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Behrens KA, Girasek QL, Sickler A, Hyde J, Buonaccorsi VP. Regions of genetic divergence in depth-separated Sebastes rockfish species pairs: Depth as a potential driver of speciation. Mol Ecol 2021; 30:4259-4275. [PMID: 34181798 DOI: 10.1111/mec.16046] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/17/2021] [Accepted: 06/24/2021] [Indexed: 12/20/2022]
Abstract
Depth separation is a proposed driver of speciation in marine fishes, with marine rockfish (genus Sebastes) providing a potentially informative study system. Sebastes rockfishes are commercially and ecologically important. This genus encompasses more than one hundred species and the ecological and morphological variance between these species provides opportunity for identifying speciation-driving adaptations, particularly along a depth gradient. A reduced-representation sequencing method (ddRADseq) was used to compare 95 individuals encompassing six Sebastes species. In this study, we sought to identify regions of divergence between species that were indicative of divergent adaptation and reproductive barriers leading to speciation. A pairwise comparison of S. chrysomelas (black-and-yellow rockfish) and S. carnatus (gopher rockfish) FST values revealed three major regions of elevated genomic divergence, two of which were also present in the S. miniatus (vermilion rockfish) and S. crocotulus (sunset rockfish) comparison. These corresponded with regions of both elevated DXY values and reduced nucleotide diversity in two cases, suggesting a speciation-with-gene-flow evolutionary model followed by post-speciation selective sweeps within each species. Limited whole-genome resequencing was also performed to identify mutations with predicted effects between S. chrysomelas and S. carnatus. Within these islands, we identified important SNPs in genes involved in immune function and vision. This supports their potential role in speciation, as these are adaptive vectors noted in other organisms. Additionally, changes to genes involved in pigment expression and mate recognition shed light on how S. chrysomelas and S. carnatus may have become reproductively isolated.
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Affiliation(s)
- Kristen A Behrens
- Department of Biology, Juniata College, Huntingdon, Pennsylvania, USA
| | - Quinn L Girasek
- Department of Biology, Juniata College, Huntingdon, Pennsylvania, USA
| | - Alex Sickler
- Center for Data Driven Discovery in Biomedicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - John Hyde
- Fisheries Resources Division, Southwest Fisheries Science Center, NOAA Fisheries, La Jolla, California, USA
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8
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Sendell-Price AT, Ruegg KC, Robertson BC, Clegg SM. An island-hopping bird reveals how founder events shape genome-wide divergence. Mol Ecol 2021; 30:2495-2510. [PMID: 33826187 DOI: 10.1111/mec.15898] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/09/2021] [Accepted: 03/18/2021] [Indexed: 12/16/2022]
Abstract
When populations colonize new areas, both strong selection and strong drift can be experienced due to novel environments and small founding populations, respectively. Empirical studies have predominantly focused on the phenotype when assessing the role of selection, and limited neutral-loci when assessing founder-induced loss of diversity. Consequently, the extent to which processes interact to influence evolutionary trajectories is difficult to assess. Genomic-level approaches provide the opportunity to simultaneously consider these processes. Here, we examine the roles of selection and drift in shaping genomic diversity and divergence in historically documented sequential island colonizations by the silvereye (Zosterops lateralis). We provide the first empirical demonstration of the rapid appearance of highly diverged genomic regions following population founding, the position of which are highly idiosyncratic. As these regions rarely contained loci putatively under selection, it is most likely that these differences arise via the stochastic nature of the founding process. However, selection is required to explain rapid evolution of larger body size in insular silvereyes. Reconciling our genomic data with these phenotypic patterns suggests there may be many genomic routes to the island phenotype, which vary across populations. Finally, we show that accelerated divergence associated with multiple founding steps is the product of genome-wide rather than localized differences, and that diversity erodes due to loss of rare alleles. However, even multiple founder events do not result in divergence and diversity levels seen in evolutionary older subspecies, and therefore do not provide a shortcut to speciation as proposed by founder-effect speciation models.
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Affiliation(s)
- Ashley T Sendell-Price
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK
| | - Kristen C Ruegg
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK.,Department of Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Sonya M Clegg
- Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, Oxford, UK.,Environmental Futures Research Institute, Griffith University, Nathan, Qld, Australia
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9
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The Genomic Landscape of Divergence Across the Speciation Continuum in Island-Colonising Silvereyes ( Zosterops lateralis). G3-GENES GENOMES GENETICS 2020; 10:3147-3163. [PMID: 32660974 PMCID: PMC7466963 DOI: 10.1534/g3.120.401352] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inferring the evolutionary dynamics at play during the process of speciation by analyzing the genomic landscape of divergence is a major pursuit in population genomics. However, empirical assessments of genomic landscapes under varying evolutionary scenarios that are known a priori are few, thereby limiting our ability to achieve this goal. Here we combine RAD-sequencing and individual-based simulations to evaluate the genomic landscape of divergence in the silvereye (Zosterops lateralis). Using pairwise comparisons that differ in divergence timeframe and the presence or absence of gene flow, we document how genomic patterns accumulate along the speciation continuum. In contrast to previous predictions, our results provide limited support for the idea that divergence accumulates around loci under divergent selection or that genomic islands widen with time. While a small number of genomic islands were found in populations diverging with and without gene flow, in few cases were SNPs putatively under selection tightly associated with genomic islands. The transition from localized to genome-wide levels of divergence was captured using individual-based simulations that considered only neutral processes. Our results challenge the ubiquity of existing verbal models that explain the accumulation of genomic differences across the speciation continuum and instead support the idea that divergence both within and outside of genomic islands is important during the speciation process.
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10
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Whiting JR, Fraser BA. Contingent Convergence: The Ability To Detect Convergent Genomic Evolution Is Dependent on Population Size and Migration. G3 (BETHESDA, MD.) 2020; 10:677-693. [PMID: 31871215 PMCID: PMC7003088 DOI: 10.1534/g3.119.400970] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/19/2019] [Indexed: 12/02/2022]
Abstract
Outlier scans, in which the genome is scanned for signatures of selection, have become a prominent tool in studies of local adaptation, and more recently studies of genetic convergence in natural populations. However, such methods have the potential to be confounded by features of demographic history, such as population size and migration, which are considerably varied across natural populations. In this study, we use forward-simulations to investigate and illustrate how several measures of genetic differentiation commonly used in outlier scans (FST, DXY and Δπ) are influenced by demographic variation across multiple sampling generations. In a factorial design with 16 treatments, we manipulate the presence/absence of founding bottlenecks (N of founding individuals), prolonged bottlenecks (proportional size of diverging population) and migration rate between two populations with ancestral and diverged phenotypic optima. Our results illustrate known constraints of individual measures associated with reduced population size and a lack of migration; but notably we demonstrate how relationships between measures are similarly dependent on these features of demography. We find that false-positive signals of convergent evolution (the same simulated outliers detected in independent treatments) are attainable as a product of similar population size and migration treatments (particularly for DXY), and that outliers across different measures (for e.g., FST and DXY) can occur with little influence of selection. Taken together, we show how underappreciated, yet quantifiable measures of demographic history can influence commonly employed methods for detecting selection.
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Affiliation(s)
- James R Whiting
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter, EX4 4QD
| | - Bonnie A Fraser
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter, EX4 4QD
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