1
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Maier PA, Vandergast AG, Bohonak AJ. Yosemite toad (Anaxyrus canorus) transcriptome reveals interplay between speciation genes and adaptive introgression. Mol Ecol 2024; 33:e17317. [PMID: 38488670 DOI: 10.1111/mec.17317] [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: 05/11/2023] [Revised: 02/15/2024] [Accepted: 02/23/2024] [Indexed: 04/09/2024]
Abstract
Genomes are heterogeneous during the early stages of speciation, with small 'islands' of DNA appearing to reflect strong adaptive differences, surrounded by vast seas of relative homogeneity. As species diverge, secondary contact zones between them can act as an interface and selectively filter through advantageous alleles of hybrid origin. Such introgression is another important adaptive process, one that allows beneficial mosaics of recombinant DNA ('rivers') to flow from one species into another. Although genomic islands of divergence appear to be associated with reproductive isolation, and genomic rivers form by adaptive introgression, it is unknown whether islands and rivers tend to be the same or different loci. We examined three replicate secondary contact zones for the Yosemite toad (Anaxyrus canorus) using two genomic data sets and a morphometric data set to answer the questions: (1) How predictably different are islands and rivers, both in terms of genomic location and gene function? (2) Are the adaptive genetic trait loci underlying tadpole growth and development reliably islands, rivers or neither? We found that island and river loci have significant overlap within a contact zone, suggesting that some loci are first islands, and later are predictably converted into rivers. However, gene ontology enrichment analysis showed strong overlap in gene function unique to all island loci, suggesting predictability in overall gene pathways for islands. Genome-wide association study outliers for tadpole development included LPIN3, a lipid metabolism gene potentially involved in climate change adaptation, that is island-like for all three contact zones, but also appears to be introgressing (as a river) across one zone. Taken together, our results suggest that adaptive divergence and introgression may be more complementary forces than currently appreciated.
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Affiliation(s)
- Paul A Maier
- Department of Biology, San Diego State University, San Diego, California, USA
- Family TreeDNA, Gene by Gene, Houston, Texas, USA
| | - Amy G Vandergast
- Western Ecological Research Center, San Diego Field Station, U.S. Geological Survey, San Diego, California, USA
| | - Andrew J Bohonak
- Department of Biology, San Diego State University, San Diego, California, USA
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2
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Ålund M, Cenzer M, Bierne N, Boughman JW, Cerca J, Comerford MS, Culicchi A, Langerhans B, McFarlane SE, Möst MH, North H, Qvarnström A, Ravinet M, Svanbäck R, Taylor SA. Anthropogenic Change and the Process of Speciation. Cold Spring Harb Perspect Biol 2023; 15:a041455. [PMID: 37788888 PMCID: PMC10691492 DOI: 10.1101/cshperspect.a041455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Anthropogenic impacts on the environment alter speciation processes by affecting both geographical contexts and selection patterns on a worldwide scale. Here we review evidence of these effects. We find that human activities often generate spatial isolation between populations and thereby promote genetic divergence but also frequently cause sudden secondary contact and hybridization between diverging lineages. Human-caused environmental changes produce new ecological niches, altering selection in diverse ways that can drive diversification; but changes also often remove niches and cause extirpations. Human impacts that alter selection regimes are widespread and strong in magnitude, ranging from local changes in biotic and abiotic conditions to direct harvesting to global climate change. Altered selection, and evolutionary responses to it, impacts early-stage divergence of lineages, but does not necessarily lead toward speciation and persistence of separate species. Altogether, humans both promote and hinder speciation, although new species would form very slowly relative to anthropogenic hybridization, which can be nearly instantaneous. Speculating about the future of speciation, we highlight two key conclusions: (1) Humans will have a large influence on extinction and "despeciation" dynamics in the short term and on early-stage lineage divergence, and thus potentially speciation in the longer term, and (2) long-term monitoring combined with easily dated anthropogenic changes will improve our understanding of the processes of speciation. We can use this knowledge to preserve and restore ecosystems in ways that promote (re-)diversification, increasing future opportunities of speciation and enhancing biodiversity.
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Affiliation(s)
- Murielle Ålund
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Meredith Cenzer
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA
| | - Nicolas Bierne
- ISEM, Université de Montpellier, CNRS, IRD, Montpellier 34095, France
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - José Cerca
- CEES - Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo 0316, Norway
| | | | - Alessandro Culicchi
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Brian Langerhans
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - S Eryn McFarlane
- Department of Botany, University of Wyoming, Laramie, Wyoming 82071, USA
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
| | - Markus H Möst
- Research Department for Limnology, University of Innsbruck, Innsbruck 6020, Austria
| | - Henry North
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Anna Qvarnström
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Mark Ravinet
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Richard Svanbäck
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado 80309, USA
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3
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Grabenstein KC, Otter KA, Burg TM, Taylor SA. Hybridization between closely related songbirds is related to human habitat disturbance. GLOBAL CHANGE BIOLOGY 2023; 29:955-968. [PMID: 36305309 DOI: 10.1111/gcb.16476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 09/14/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Human habitat disturbances can promote hybridization between closely related, but typically reproductively isolated, species. We explored whether human habitat disturbances are related to hybridization between two closely related songbirds, black-capped and mountain chickadees, using both genomic and citizen science data sets. First, we genotyped 409 individuals from across both species' ranges using reduced-representation genome sequencing and compared measures of genetic admixture to a composite measure of human landscape disturbance. Then, using eBird observations, we compared human landscape disturbance values for sites where phenotypically diagnosed hybrids were observed to locations where either parental species was observed to determine whether hybrid chickadees are reported in more disturbed areas. We found that hybridization between black-capped and mountain chickadees positively correlates with human habitat disturbances. From genomic data, we found that (1) hybrid index (HI) significantly increased with habitat disturbance, (2) more hybrids were sampled in disturbed habitats, (3) mean HIs were higher in disturbed habitats versus wild habitats, and (4) hybrids were detected in habitats with significantly higher disturbance values than parentals. Using eBird data, we found that both hybrid and black-capped chickadees were significantly more disturbance-associated than mountain chickadees. Surprisingly, we found that nearly every black-capped chickadee we sampled contained some proportion of hybrid ancestry, while we detected very few mountain chickadee backcrosses. Our results highlight that hybridization between black-capped and mountain chickadees is widespread, but initial hybridization is rare (few F1s were detected). We conclude that human habitat disturbances can erode pre-zygotic reproductive barriers between chickadees and that post-zygotic isolation is incomplete. Understanding what becomes of recently hybridizing species following large-scale habitat disturbances is a new, but pressing, consideration for successfully preserving genetic biodiversity in a rapidly changing world.
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Affiliation(s)
- Kathryn C Grabenstein
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Ken A Otter
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, British Columbia, Canada
| | - Theresa M Burg
- Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, USA
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4
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Alexander A, Robbins MB, Holmes J, Moyle RG, Peterson AT. Limited movement of an avian hybrid zone in relation to regional variation in magnitude of climate change. Mol Ecol 2022; 31:6634-6648. [PMID: 36210655 PMCID: PMC9729445 DOI: 10.1111/mec.16727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 01/13/2023]
Abstract
Studies of natural hybrid zones can provide documentation of range shifts in response to climate change and identify loci important to reproductive isolation. Using a temporal (36-38 years) comparison of the black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee hybrid zone, we investigated movement of the western portion of the zone (western Missouri) and assessed whether loci and pathways underpinning reproductive isolation were similar to those in the eastern portion of the hybrid zone. Using 92 birds sampled along the hybrid zone transect in 2016 and 68 birds sampled between 1978 and 1980, we generated 11,669 SNPs via ddRADseq. These SNPs were used to assess movement of the hybrid zone through time and to evaluate variation in introgression among loci. We demonstrate that the interface has moved ~5 km to the northwest over the last 36-38 years, that is, at only one-fifth the rate at which the eastern portion (e.g., Pennsylvania, Ohio) of the hybrid zone has moved. Temperature trends over the last 38 years reveal that eastern areas have warmed 50% more than western areas in terms of annual mean temperature, possibly providing an explanation for the slower movement of the hybrid zone in Missouri. Our results suggest hybrid zone movement in broadly distributed species, such as chickadees, will vary between areas in response to local differences in the impacts of climate change.
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Affiliation(s)
- Alana Alexander
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.,Corresponding author.
| | - Mark B. Robbins
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA
| | - Jesse Holmes
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - Robert G. Moyle
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - A. Townsend Peterson
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
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5
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Grabenstein KC, Otter KA, Burg TM, Taylor SA. Sympatry leads to reduced body condition in chickadees that occasionally hybridize. Ecol Evol 2022; 12:e8756. [PMID: 35386870 PMCID: PMC8975787 DOI: 10.1002/ece3.8756] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/21/2022] [Accepted: 03/01/2022] [Indexed: 12/13/2022] Open
Abstract
Both abiotic and biotic drivers influence species distributions. Abiotic drivers such as climate have received considerable attention, even though biotic drivers such as hybridization often interact with abiotic drivers. We sought to explore the (1) costs of co‐occurrence for ecologically similar species that hybridize and (2) associations between ecological factors and condition to understand how abiotic and biotic factors influence species distributions. For two closely related and ecologically similar songbirds, black‐capped and mountain chickadees, we characterized body condition, as a proxy for fitness, using a 1358‐individual range‐wide dataset. We compared body condition in sympatry and allopatry with several abiotic and biotic factors using species‐specific generalized linear mixed models. We generated genomic data for a subset of 217 individuals to determine the extent of hybridization‐driven admixture in our dataset. Within this data subset, we found that ~11% of the chickadees had hybrid ancestry, and all hybrid individuals had typical black‐capped chickadee plumage. In the full dataset, we found that birds of both species, independent of demographic and abiotic factors, had significantly lower body condition when occurring in sympatry than birds in allopatry. This could be driven by either the inclusion of cryptic, likely poor condition, hybrids in our full dataset, competitive interactions in sympatry, or range edge effects. We are currently unable to discriminate between these mechanisms. Our findings have implications for mountain chickadees in particular, which will encounter more black‐capped chickadees as black‐capped chickadee ranges shift upslope and could lead to local declines in mountain chickadee populations.
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Affiliation(s)
- Kathryn C. Grabenstein
- Ecology and Evolutionary Biology University of Colorado at Boulder Boulder Colorado USA
| | - Ken A. Otter
- Natural Resources and Environmental Studies University of Northern British Columbia Prince George British Columbia Canada
| | | | - Scott A. Taylor
- Ecology and Evolutionary Biology University of Colorado at Boulder Boulder Colorado USA
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6
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Driver R, Ferretti V, Burton ES, McCoy MW, Duerr KC, Curry RL. Spatiotemporal variation in hatching success and nestling sex ratios track rapid movement of a songbird hybrid zone. Am Nat 2022; 200:264-274. [DOI: 10.1086/720207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Odor preferences in hybrid chickadees: implications for reproductive isolation and asymmetric introgression. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03069-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Fraïsse C, Sachdeva H. The rates of introgression and barriers to genetic exchange between hybridizing species: sex chromosomes vs autosomes. Genetics 2021; 217:6042694. [PMID: 33724409 DOI: 10.1093/genetics/iyaa025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/23/2020] [Indexed: 12/14/2022] Open
Abstract
Interspecific crossing experiments have shown that sex chromosomes play a major role in reproductive isolation between many pairs of species. However, their ability to act as reproductive barriers, which hamper interspecific genetic exchange, has rarely been evaluated quantitatively compared to Autosomes. This genome-wide limitation of gene flow is essential for understanding the complete separation of species, and thus speciation. Here, we develop a mainland-island model of secondary contact between hybridizing species of an XY (or ZW) sexual system. We obtain theoretical predictions for the frequency of introgressed alleles, and the strength of the barrier to neutral gene flow for the two types of chromosomes carrying multiple interspecific barrier loci. Theoretical predictions are obtained for scenarios where introgressed alleles are rare. We show that the same analytical expressions apply for sex chromosomes and autosomes, but with different sex-averaged effective parameters. The specific features of sex chromosomes (hemizygosity and absence of recombination in the heterogametic sex) lead to reduced levels of introgression on the X (or Z) compared to autosomes. This effect can be enhanced by certain types of sex-biased forces, but it remains overall small (except when alleles causing incompatibilities are recessive). We discuss these predictions in the light of empirical data comprising model-based tests of introgression and cline surveys in various biological systems.
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Affiliation(s)
- Christelle Fraïsse
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria.,CNRS, Univ. Lille, UMR 8198 - Evo-Eco-Paleo, F-59000 Lille, France
| | - Himani Sachdeva
- Institute of Science and Technology Austria, Klosterneuburg 3400, Austria.,Mathematics and BioSciences Group, Faculty of Mathematics, University of Vienna, A-1090 Vienna, Austria
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9
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Jahner JP, Parchman TL, Matocq MD. Multigenerational backcrossing and introgression between two woodrat species at an abrupt ecological transition. Mol Ecol 2021; 30:4245-4258. [PMID: 34219316 DOI: 10.1111/mec.16056] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/28/2021] [Indexed: 12/27/2022]
Abstract
When organisms experience secondary contact after allopatric divergence, genomic regions can introgress differentially depending on their relationships with adaptation, reproductive isolation, recombination, and drift. Analyses of genome-wide patterns of divergence and introgression could provide insight into the outcomes of hybridization and the potential relationship between allopatric divergence and reproductive isolation. Here, we generate population genetic data (26,262 SNPs; 353 individuals) using a reduced-representation sequencing approach to quantify patterns of ancestry, differentiation, and introgression between a pair of ecologically distinct mammals-the desert woodrat (N. lepida) and Bryant's woodrat (N. bryanti)-that hybridize at a sharp ecotone in southern California. Individual ancestry estimates confirmed that hybrids were rare in this bimodal hybrid zone, and entirely consisted of a few F1 individuals and a broad range of multigenerational backcrosses. Genomic cline analyses indicated more than half of loci had elevated introgression from one genomic background into the other. However, introgression was not associated with relative or absolute measures of divergence, and loci with extreme values for both were not typically found near detoxification enzymes previously implicated in dietary specialization for woodrats. The decoupling of differentiation and introgression suggests that processes other than adaptation, such as drift, may underlie the extreme clines at this contact zone.
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Affiliation(s)
- Joshua P Jahner
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Department of Botany, University of Wyoming, Laramie, Wyoming, USA
| | - Thomas L Parchman
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
| | - Marjorie D Matocq
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.,Department of Natural Resources and Environmental Science, University of Nevada, Reno, Nevada, USA
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10
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Leighton GM, Lu LJ, Holop E, Dobler J, Ligon RA. Sociality and migration predict hybridization across birds. Proc Biol Sci 2021; 288:20201946. [PMID: 33726589 DOI: 10.1098/rspb.2020.1946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hybridization represents a natural experiment that can provide insight into processes of speciation and diversification. Though considerable research has focused on hybrid zone dynamics, macroevolutionary investigations of the factors that influence hybridization are few. Here, we compile a database of avian hybrids and perform comparative analyses to determine whether several social and life-history variables influence broad patterns of hybridization. We perform three main analyses: phylogenetic logistic regression to examine variables that are associated with the presence of hybridization, phylogenetic Poisson regression of only those species exhibiting hybridization to determine which variables are associated with the extent of hybridization, and a phylogenetic logistic regression on a subset of data to assess potential pseudoreplication. After testing several social and life-history variables, we found that social bond duration is associated with the presence and extent of hybridization. Specifically, lengthy social bonds are negatively associated with the presence and extent of hybridization. In addition to social bond length, migration is positively linked with a greater likelihood of hybridization. The broad-scale correlations between species-specific traits and hybridization across diverse avian lineages suggest commonalities in the fine-scale processes involved in mating with heterospecifics, which in turn has implications for how we think about, study and understand hybridization processes and their influence on evolutionary trajectories.
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Affiliation(s)
- Gavin M Leighton
- Department of Biology, SUNY Buffalo State College, Buffalo, NY 14213, USA.,Department of Neurobiology & Behavior, Cornell Lab of Ornithology, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
| | - Lucy Jingyi Lu
- Department of Neurobiology & Behavior, Cornell Lab of Ornithology, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
| | - Eliot Holop
- Department of Neurobiology & Behavior, Cornell Lab of Ornithology, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
| | - Jessica Dobler
- Department of Neurobiology & Behavior, Cornell Lab of Ornithology, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
| | - Russell A Ligon
- Department of Neurobiology & Behavior, Cornell Lab of Ornithology, Cornell University, 215 Tower Road, Ithaca, NY 14850, USA
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11
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McFarlane SE, Senn HV, Smith SL, Pemberton JM. Locus-specific introgression in young hybrid swarms: Drift may dominate selection. Mol Ecol 2021; 30:2104-2115. [PMID: 33638185 DOI: 10.1111/mec.15862] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 02/01/2021] [Accepted: 02/17/2021] [Indexed: 12/17/2022]
Abstract
Closely related species that have previously inhabited geographically separated ranges are hybridizing at an increasing rate due to human disruptions. These human-mediated hybrid zones can be used to study reproductive isolation between species at secondary contact, including examining locus-specific rates of introgression. Introgression is expected to be heterogenous across the genome, reflecting variation in selection. Those loci that introgress especially slowly are good candidates for being involved in reproductive isolation, while those loci that introgress quickly may be involved in adaptive introgression. In the context of conservation, policy makers are especially concerned about introduced alleles moving quickly into the background of a native or endemic species, as these alleles could replace the native alleles in the population, leading to extinction via hybridization. We applied genomic cline analyses to 44,997 SNPs to identify loci introgressing more or less when compared to the genome wide expectation in a human-mediated hybridizing population of red deer and sika in Kintyre Scotland. We found 11.4% of SNPs had cline centres that were significantly different from the genome wide expectation, and 17.6% of all SNPs had excess rates of introgression. Based on simulations, we believe that many of these markers have diverged from the genome-wide average due to drift, rather than because of selection, and we suggest that these simulations can be useful as a null distribution for future studies of genomic clines. Future work on red deer and sika could determine the policy implications of allelic-replacement due to drift rather than selection, and could use replicate, geographically distinct hybrid zones to narrow down those loci that are responding to selection.
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Affiliation(s)
- S Eryn McFarlane
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.,Department of Biology, Lund University, Lund, Sweden
| | - Helen V Senn
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.,WildGenes Laboratory, Royal Zoological Society of Scotland, Edinburgh, UK
| | - Stephanie L Smith
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.,The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Campus, Edinburgh, UK
| | - Josephine M Pemberton
- School of Biological Sciences, Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
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12
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Tobias JA, Ottenburghs J, Pigot AL. Avian Diversity: Speciation, Macroevolution, and Ecological Function. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-110218-025023] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The origin, distribution, and function of biological diversity are fundamental themes of ecology and evolutionary biology. Research on birds has played a major role in the history and development of these ideas, yet progress was for many decades limited by a focus on patterns of current diversity, often restricted to particular clades or regions. Deeper insight is now emerging from a recent wave of integrative studies combining comprehensive phylogenetic, environmental, and functional trait data at unprecedented scales. We review these empirical advances and describe how they are reshaping our understanding of global patterns of bird diversity and the processes by which it arises, with implications for avian biogeography and functional ecology. Further expansion and integration of data sets may help to resolve longstanding debates about the evolutionary origins of biodiversity and offer a framework for understanding and predicting the response of ecosystems to environmental change.
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Affiliation(s)
- Joseph A. Tobias
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot SL5 7PY, United Kingdom
| | - Jente Ottenburghs
- Department of Evolutionary Biology, Uppsala University, 752 36 Uppsala, Sweden
| | - Alex L. Pigot
- Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
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13
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Schnitzler CK, Turchetto C, Teixeira MC, Freitas LB. What could be the fate of secondary contact zones between closely related plant species? Genet Mol Biol 2020; 43:e20190271. [PMID: 32556035 PMCID: PMC7299303 DOI: 10.1590/1678-4685-gmb-2019-0271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 03/24/2020] [Indexed: 11/26/2022] Open
Abstract
Interspecific hybridization has been fundamental in plant evolution.
Nevertheless, the fate of hybrid zones throughout the generations remains poorly
addressed. We analyzed a pair of recently diverged, interfertile, and sympatric
Petunia species to ask what fate the interspecific hybrid
population has met over time. We analyzed the genetic diversity in two
generations from two contact sites and evaluated the effect of introgression. To
do this, we collected all adult plants from the contact zones, including
canonicals and intermediary colored individuals, and compared them with purebred
representatives of both species based on seven highly informative microsatellite
loci. We compared the genetic diversity observed in the contact zones with what
is seen in isolated populations of each species, considering two generations of
these annual species. Our results have confirmed the genetic differentiation
between the species and the hybrid origin of the majority of the intermediary
colored individuals. We also observed a differentiation related to genetic
variability and inbreeding levels among the populations. Over time, there were
no significant differences per site related to genetic diversity or phenotype
composition. We found two stable populations kept by high inbreeding and
backcross rates that influence the genetic diversity of their parental species
through introgression.
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Affiliation(s)
- Carolina K Schnitzler
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Caroline Turchetto
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Marcelo C Teixeira
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
| | - Loreta B Freitas
- Universidade Federal do Rio Grande do Sul, Departamento de Genética, Laboratório de Evolução Molecular, Porto Alegre, RS, Brazil
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14
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McGoey BV, Hodgins KA, Stinchcombe JR. Parallel flowering time clines in native and introduced ragweed populations are likely due to adaptation. Ecol Evol 2020; 10:4595-4608. [PMID: 32551046 PMCID: PMC7297792 DOI: 10.1002/ece3.6163] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 01/06/2023] Open
Abstract
As introduced species expand their ranges, they often encounter differences in climate which are often correlated with geography. For introduced species, encountering a geographically variable climate sometimes leads to the re-establishment of clines seen in the native range. However, clines can also be caused by neutral processes, and so it is important to gather additional evidence that population differentiation is the result of selection as opposed to nonadaptive processes. Here, we examine phenotypic and genetic differences in ragweed from the native (North America) and introduced (European) ranges. We used a common garden to assess phenotypic differentiation in size and flowering time in ragweed populations. We found significant parallel clines in flowering time in both North America and Europe. Height and branch number had significant clines in North America, and, while not statistically significant, the patterns in Europe were the same. We used SNP data to assess population structure in both ranges and to compare phenotypic differentiation to neutral genetic variation. We failed to detect significant patterns of isolation by distance, geographic patterns in population structure, or correlations between the major axes of SNP variation and phenotypes or latitude of origin. We conclude that the North American clines in size and the parallel clines seen for flowering time are most likely the result of adaptation.
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Affiliation(s)
- Brechann V. McGoey
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | | | - John R. Stinchcombe
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
- Koffler Scientific ReserveUniversity of TorontoTorontoONCanada
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15
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Wagner DN, Curry RL, Chen N, Lovette IJ, Taylor SA. Genomic regions underlying metabolic and neuronal signaling pathways are temporally consistent in a moving avian hybrid zone. Evolution 2020; 74:1498-1513. [PMID: 32243568 DOI: 10.1111/evo.13970] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 12/15/2022]
Abstract
The study of hybrid zones can provide insight into the genetic basis of species differences that are relevant for the maintenance of reproductive isolation. Hybrid zones can also provide insight into climate change, species distributions, and evolution. The hybrid zone between black-capped chickadees (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis) is shifting northward in response to increasing winter temperatures but is not increasing in width. This pattern indicates strong selection against chickadees with admixed genomes. Using high-resolution genomic data, we identified regions of the genomes that are outliers in both time points and do not introgress between the species; these regions may be involved in the maintenance of reproductive isolation. Genes involved in metabolic regulation processes were overrepresented in this dataset. Several gene ontology categories were also temporally consistent-including glutamate signaling, synaptic transmission, and catabolic processes-but the nucleotide variants leading to this pattern were not. Our results support recent findings that hybrids between black-capped and Carolina chickadees have higher basal metabolic rates than either parental species and suffer spatial memory and problem-solving deficits. Metabolic breakdown, as well as spatial memory and problem-solving, in hybrid chickadees may act as strong postzygotic isolation mechanisms in this moving hybrid zone.
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Affiliation(s)
- Dominique N Wagner
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
| | - Robert L Curry
- Department of Biology, Villanova University, Villanova, Pennsylvania, 19085
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, New York, 14627
| | - Irby J Lovette
- Cornell Lab of Ornithology, Cornell University, Ithaca, New York, 14850
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
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16
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Ebersbach J, Posso-Terranova A, Bogdanowicz S, Gómez-Díaz M, García-González MX, Bolívar-García W, Andrés J. Complex patterns of differentiation and gene flow underly the divergence of aposematic phenotypes in Oophaga poison frogs. Mol Ecol 2020; 29:1944-1956. [PMID: 31971303 DOI: 10.1111/mec.15360] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/11/2019] [Accepted: 01/04/2020] [Indexed: 12/16/2022]
Abstract
Hybridization and introgression can have complex consequences for both species evolution and conservation. Here, we investigated the origin and characteristics of a putative hybrid zone between two South American poison dart frog species, Oophaga anchicayensis and the critically endangered Oophaga lehmanni, which are heavily sought after on the illegal pet market. Using a combination of phenotypic (49 traits) and genomic (ddRADseq) data, we found that the putative hybrids are morphologically distinct from their parental species and confirmed genomic signatures of admixture in these populations. Several lines of evidence (hybrid indices, interspecific hybrid heterozygosity, genomic clines, comparisons with simulated hybrids and demographic modelling) support the conclusion that these populations are not comprised of early-generation hybrids and thus, they probably did not arise as a result of illegal translocations associated with wildlife trafficking. Instead, they probably represent an independent lineage which has persisted through isolation and has only relatively recently re-established gene flow with both parental species. Furthermore, we detected signals of differential introgression from parental species into these hybrid populations which suggest relaxed stabilizing selection on these aposematic colour morphs, potentially via context-dependent female choice. These populations thus provide a fascinating window into the role of hybridization, isolation and female choice in the diversification of South American poison dart frogs. In addition, our results underline the importance of landscape conservation measures to protect, not only known localities of nominal species, but also the phenotypic and genomic variation harbored by admixed lineages which represent crucial repositories for the impressive diversity in this system.
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Affiliation(s)
- Jana Ebersbach
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Andrés Posso-Terranova
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Facultad de Ciencias Agropecuarias, Universidad Nacional de Colombia sede Palmira, Palmira, Colombia
| | - Steven Bogdanowicz
- Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
| | - Mónica Gómez-Díaz
- Research Group in Animal Ecology, Department of Biology, Universidad del Valle, Cali, Colombia
| | | | - Wilmar Bolívar-García
- Research Group in Animal Ecology, Department of Biology, Universidad del Valle, Cali, Colombia
| | - José Andrés
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,Department of Ecology and Evolution, Cornell University, Ithaca, NY, USA
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17
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Menon M, Landguth E, Leal‐Saenz A, Bagley JC, Schoettle AW, Wehenkel C, Flores‐Renteria L, Cushman SA, Waring KM, Eckert AJ. Tracing the footprints of a moving hybrid zone under a demographic history of speciation with gene flow. Evol Appl 2020; 13:195-209. [PMID: 31892952 PMCID: PMC6935588 DOI: 10.1111/eva.12795] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/20/2019] [Accepted: 03/19/2019] [Indexed: 02/07/2023] Open
Abstract
A lack of optimal gene combinations, as well as low levels of genetic diversity, is often associated with the formation of species range margins. Conservation efforts rely on predictive modelling using abiotic variables and assessments of genetic diversity to determine target species and populations for controlled breeding, germplasm conservation and assisted migration. Biotic factors such as interspecific competition and hybridization, however, are largely ignored, despite their prevalence across diverse taxa and their role as key evolutionary forces. Hybridization between species with well-developed barriers to reproductive isolation often results in the production of offspring with lower fitness. Generation of novel allelic combinations through hybridization, however, can also generate positive fitness consequences. Despite this possibility, hybridization-mediated introgression is often considered a threat to biodiversity as it can blur species boundaries. The contribution of hybridization towards increasing genetic diversity of populations at range margins has only recently gathered attention in conservation studies. We assessed the extent to which hybridization contributes towards range dynamics by tracking spatio-temporal changes in the central location of a hybrid zone between two recently diverged species of pines: Pinus strobiformis and P. flexilis. By comparing geographic cline centre estimates for global admixture coefficient with morphological traits associated with reproductive output, we demonstrate a northward shift in the hybrid zone. Using a combination of spatially explicit, individual-based simulations and linkage disequilibrium variance partitioning, we note a significant contribution of adaptive introgression towards this northward movement, despite the potential for differences in regional population size to aid hybrid zone movement. Overall, our study demonstrates that hybridization between recently diverged species can increase genetic diversity and generate novel allelic combinations. These novel combinations may allow range margin populations to track favourable climatic conditions or facilitate adaptive evolution to ongoing and future climate change.
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Affiliation(s)
- Mitra Menon
- Integrative Life SciencesVirginia Commonwealth UniversityRichmondVirginia
| | - Erin Landguth
- School of Public and Community Health SciencesUniversity of MontanaMissoulaMontana
| | - Alejandro Leal‐Saenz
- Programa Institucional de Doctorado en Ciencias Agropecuarias y ForestalesUniversidad Juárez del Estado de DurangoDurangoMexico
| | - Justin C. Bagley
- Department of BiologyVirginia Commonwealth UniversityRichmondVirginia
| | - Anna W. Schoettle
- Rocky Mountain Research StationUSDA Forest ServiceFort CollinsColorado
| | - Christian Wehenkel
- Instituto de Silvicultura e Industria de la MaderaUniversidad Juarez del Estado de DurangoDurangoMexico
| | | | | | | | - Andrew J. Eckert
- Department of BiologyVirginia Commonwealth UniversityRichmondVirginia
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18
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Joseph L, Drew A, Mason IJ, Peters JL. Introgression between non-sister species of honeyeaters (Aves: Meliphagidae) several million years after speciation. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AbstractWe reassessed whether two parapatric non-sister Australian honeyeater species (Aves: Meliphagidae), varied and mangrove honeyeaters (Gavicalis versicolor and G. fasciogularis, respectively), that diverged from a common ancestor c. 2.5 Mya intergrade in the Townsville area of north-eastern Queensland. Consistent with a previous specimen-based study, by using genomics methods we show one-way gene flow for autosomal but not Z-linked markers from varied into mangrove honeyeaters. Introgression barely extends south of the area of parapatry in and around the city of Townsville. While demonstrating the long-term porosity of species boundaries over several million years, our data also suggest a clear role of sex chromosomes in maintaining reproductive isolation.
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Affiliation(s)
- Leo Joseph
- Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, ACT, Australia
| | - Alex Drew
- Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, ACT, Australia
| | - Ian J Mason
- Australian National Wildlife Collection, National Research Collections Australia, CSIRO, Canberra, ACT, Australia
| | - Jeffrey L Peters
- Department of Biological Sciences, Wright State University, Dayton, OH, USA
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19
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Van Huynh A, Rice AM. Conspecific olfactory preferences and interspecific divergence in odor cues in a chickadee hybrid zone. Ecol Evol 2019; 9:9671-9683. [PMID: 31534684 PMCID: PMC6745874 DOI: 10.1002/ece3.5497] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/11/2019] [Accepted: 07/06/2019] [Indexed: 12/25/2022] Open
Abstract
Understanding how mating cues promote reproductive isolation upon secondary contact is important in describing the speciation process in animals. Divergent chemical cues have been shown to act in reproductive isolation across many animal taxa. However, such cues have been overlooked in avian speciation, particularly in passerines, in favor of more traditional signals such as song and plumage. Here, we aim to test the potential for odor to act as a mate choice cue, and therefore contribute to premating reproductive isolation between the black-capped (Poecile atricapillus) and Carolina chickadee (P. carolinensis) in eastern Pennsylvania hybrid zone populations. Using gas chromatography-mass spectrometry, we document significant species differences in uropygial gland oil chemistry, especially in the ratio of ester to nonester compounds. We also show significant preferences for conspecific over heterospecific odor cues in wild chickadees using a Y-maze design. Our results suggest that odor may be an overlooked but important mating cue in these chickadees, potentially promoting premating reproductive isolation. We further discuss several promising avenues for future research in songbird olfactory communication and speciation.
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Affiliation(s)
- Alex Van Huynh
- Department of Biological SciencesLehigh UniversityBethlehemPAUSA
| | - Amber M. Rice
- Department of Biological SciencesLehigh UniversityBethlehemPAUSA
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20
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Rifkin JL, Castillo AS, Liao IT, Rausher MD. Gene flow, divergent selection and resistance to introgression in two species of morning glories (Ipomoea). Mol Ecol 2019; 28:1709-1729. [PMID: 30451335 DOI: 10.1111/mec.14945] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 09/03/2018] [Accepted: 11/01/2018] [Indexed: 02/03/2023]
Abstract
Gene flow is thought to impede genetic divergence and speciation by homogenizing genomes. Recent theory and research suggest that sufficiently strong divergent selection can overpower gene flow, leading to loci that are highly differentiated compared to others. However, there are also alternative explanations for this pattern. Independent evidence that loci in highly differentiated regions are under divergent selection would allow these explanations to be distinguished, but such evidence is scarce. Here, we present multiple lines of evidence that many of the highly divergent SNPs in a pair of sister morning glory species, Ipomoea cordatotriloba and I. lacunosa, are the result of divergent selection in the face of gene flow. We analysed a SNP data set across the genome to assess the amount of gene flow, resistance to introgression and patterns of selection on loci resistant to introgression. We show that differentiation between the two species is much lower in sympatry than in allopatry, consistent with interspecific gene flow in sympatry. Gene flow appears to be substantially greater from I. lacunosa to I. cordatotriloba than in the reverse direction, resulting in sympatric and allopatric I. cordatotriloba being substantially more different than sympatric and allopatric I. lacunosa. Many SNPs highly differentiated in allopatry have experienced divergent selection, and, despite gene flow in sympatry, resist homogenization in sympatry. Finally, five out of eight floral and inflorescence characteristics measured exhibit asymmetric convergence in sympatry. Consistent with the pattern of gene flow, I. cordatotriloba traits become much more like those of I. lacunosa than the reverse. Our investigation reveals the complex interplay between selection and gene flow that can occur during the early stages of speciation.
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Affiliation(s)
- Joanna L Rifkin
- Department of Biology, Duke University, Durham, North Carolina
| | | | - Irene T Liao
- Department of Biology, Duke University, Durham, North Carolina
| | - Mark D Rausher
- Department of Biology, Duke University, Durham, North Carolina
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21
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Pulido-Santacruz P, Aleixo A, Weir JT. Morphologically cryptic Amazonian bird species pairs exhibit strong postzygotic reproductive isolation. Proc Biol Sci 2019. [PMID: 29514967 DOI: 10.1098/rspb.2017.2081] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We possess limited understanding of how speciation unfolds in the most species-rich region of the planet-the Amazon basin. Hybrid zones provide valuable information on the evolution of reproductive isolation, but few studies of Amazonian vertebrate hybrid zones have rigorously examined the genome-wide underpinnings of reproductive isolation. We used genome-wide genetic datasets to show that two deeply diverged, but morphologically cryptic sister species of forest understorey birds show little evidence for prezygotic reproductive isolation, but substantial postzygotic isolation. Patterns of heterozygosity and hybrid index revealed that hybrid classes with heavily recombined genomes are rare and closely match simulations with high levels of selection against hybrids. Genomic and geographical clines exhibit a remarkable similarity across loci in cline centres, and have exceptionally narrow cline widths, suggesting that postzygotic isolation is driven by genetic incompatibilities at many loci, rather than a few loci of strong effect. We propose Amazonian understorey forest birds speciate slowly via gradual accumulation of postzygotic genetic incompatibilities, with prezygotic barriers playing a less important role. Our results suggest old, cryptic Amazonian taxa classified as subspecies could have substantial postzygotic isolation deserving species recognition and that species richness is likely to be substantially underestimated in Amazonia.
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Affiliation(s)
| | - Alexandre Aleixo
- Department of Zoology, Museu Paraense Emílio Goeldi, Belém, Brazil
| | - Jason T Weir
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada .,Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada
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22
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Dissection by genomic and plumage variation of a geographically complex hybrid zone between two Australian non-sister parrot species, Platycercus adscitus and Platycercus eximius. Heredity (Edinb) 2018; 122:402-416. [PMID: 30082918 PMCID: PMC6460760 DOI: 10.1038/s41437-018-0127-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 06/23/2018] [Accepted: 06/27/2018] [Indexed: 01/27/2023] Open
Abstract
The study of hybrid zones advances understanding of the speciation process, and approaches incorporating genomic data are increasingly used to draw significant conclusions about the impact of hybridisation. Despite the progress made, the complex interplay of factors that can lead to substantially variable hybridisation outcomes are still not well understood, and many systems and/or groups remain comparatively poorly studied. Our study aims to broaden the literature on avian hybrid zones, investigating a potentially geographically and temporally complex putative hybrid zone between two native Australian non-sister parrot species, the pale-headed and eastern rosellas (Platycercus adscitus and Platycercus eximius, respectively). We analysed six plumage traits and >1400 RADseq loci and detected hybrid individuals and an unexpectedly complex geographic structure. The hybrid zone is larger than previously described due to either observer bias or its movement over recent decades. It comprises different subregions where genetic and plumage signals of admixture vary markedly in their concordance. Evidence of contemporary hybridisation (later generation and backcrossed individuals) both within and beyond the previously defined zone, when coupled with a lack of F1 hybrids and differential patterns of introgression among potentially diagnostic loci, indicates a lack of post-zygotic barriers to gene flow between species. Despite ongoing gene flow, species boundaries are likely maintained largely by strong pre-mating barriers. These findings are discussed in detail and future avenues for research into this system are proposed, which would be of benefit to the speciation and hybrid zone literature.
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23
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Arntzen JW, Üzüm N, Ajduković MD, Ivanović A, Wielstra B. Absence of heterosis in hybrid crested newts. PeerJ 2018; 6:e5317. [PMID: 30065885 PMCID: PMC6063215 DOI: 10.7717/peerj.5317] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/04/2018] [Indexed: 11/27/2022] Open
Abstract
Relationships between phylogenetic relatedness, hybrid zone spatial structure, the amount of interspecific gene flow and population demography were investigated, with the newt genus Triturus as a model system. In earlier work, a bimodal hybrid zone of two distantly related species combined low interspecific gene flow with hybrid sterility and heterosis was documented. Apart from that, a suite of unimodal hybrid zones in closely related Triturus showed more or less extensive introgressive hybridization with no evidence for heterosis. We here report on population demography and interspecific gene flow in two Triturus species (T. macedonicus and T. ivanbureschi in Serbia). These are two that are moderately related, engage in a heterogeneous uni-/bimodal hybrid zone and hence represent an intermediate situation. This study used 13 diagnostic nuclear genetic markers in a population at the species contact zone. This showed that all individuals were hybrids, with no parentals detected. Age, size and longevity and the estimated growth curves are not exceeding that of the parental species, so that we conclude the absence of heterosis in T. macedonicus-T. ivanbureschi. Observations across the genus support the hypothesis that fertile hybrids allocate resources to reproduction and infertile hybrids allocate resources to growth. Several Triturus species hybrid zones not yet studied allow the testing of this hypothesis.
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Affiliation(s)
| | - Nazan Üzüm
- Department of Biology, Faculty of Arts and Sciences, Adnan Menderes University, Aydin, Turkey
| | - Maja D. Ajduković
- Institute for Biological Research “Siniša Stanković”, University of Belgrade, Belgrade, Serbia
| | - Ana Ivanović
- Naturalis Biodiversity Center, Leiden, The Netherlands
- Institute of Zoology, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Ben Wielstra
- Naturalis Biodiversity Center, Leiden, The Netherlands
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
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24
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Jackson JM, Pimsler ML, Oyen KJ, Koch‐Uhuad JB, Herndon JD, Strange JP, Dillon ME, Lozier JD. Distance, elevation and environment as drivers of diversity and divergence in bumble bees across latitude and altitude. Mol Ecol 2018; 27:2926-2942. [DOI: 10.1111/mec.14735] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Jason M. Jackson
- Department of Biological Sciences The University of Alabama Tuscaloosa Alabama
| | - Meaghan L. Pimsler
- Department of Biological Sciences The University of Alabama Tuscaloosa Alabama
| | - Kennan Jeannet Oyen
- Department of Zoology & Physiology and Program in Ecology University of Wyoming Laramie Wyoming
| | - Jonathan B. Koch‐Uhuad
- Tropical Conservation Biology & Environmental Science Graduate Program Department of Biology University of Hawaii at Hilo Hilo Hawaii
| | - James D. Herndon
- USDA‐ARS Pollinating Insect Research Unit Utah State University Logan Utah
| | - James P. Strange
- USDA‐ARS Pollinating Insect Research Unit Utah State University Logan Utah
| | - Michael E. Dillon
- Department of Zoology & Physiology and Program in Ecology University of Wyoming Laramie Wyoming
| | - Jeffrey D. Lozier
- Department of Biological Sciences The University of Alabama Tuscaloosa Alabama
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25
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Rice AM, McQuillan MA. Maladaptive learning and memory in hybrids as a reproductive isolating barrier. Proc Biol Sci 2018; 285:20180542. [PMID: 29848649 PMCID: PMC5998094 DOI: 10.1098/rspb.2018.0542] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/10/2018] [Indexed: 01/02/2023] Open
Abstract
Selection against hybrid offspring, or postzygotic reproductive isolation, maintains species boundaries in the face of gene flow from hybridization. In this review, we propose that maladaptive learning and memory in hybrids is an important, but overlooked form of postzygotic reproductive isolation. Although a role for learning in premating isolation has been supported, whether learning deficiencies can contribute to postzygotic isolation has rarely been tested. We argue that the novel genetic combinations created by hybridization have the potential to impact learning and memory abilities through multiple possible mechanisms, and that any displacement from optima in these traits is likely to have fitness consequences. We review evidence supporting the potential for hybridization to affect learning and memory, and evidence of links between learning abilities and fitness. Finally, we suggest several avenues for future research. Given the importance of learning for fitness, especially in novel and unpredictable environments, maladaptive learning and memory in hybrids may be an increasingly important source of postzygotic reproductive isolation.
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Affiliation(s)
- Amber M Rice
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Michael A McQuillan
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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26
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Sciuchetti L, Dufresnes C, Cavoto E, Brelsford A, Perrin N. Dobzhansky-Muller incompatibilities, dominance drive, and sex-chromosome introgression at secondary contact zones: A simulation study. Evolution 2018; 72:1350-1361. [PMID: 29806172 DOI: 10.1111/evo.13510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 05/08/2018] [Indexed: 11/28/2022]
Abstract
Dobzhansky-Muller (DM) incompatibilities involving sex chromosomes have been proposed to account for Haldane's rule (lowered fitness among hybrid offspring of the heterogametic sex) as well as Darwin's corollary (asymmetric fitness costs with respect to the direction of the cross). We performed simulation studies of a hybrid zone to investigate the effects of different types of DM incompatibilities on cline widths and positions of sex-linked markers. From our simulations, X-Y incompatibilities generate steep clines for both X-linked and Y-linked markers; random effects may produce strong noise in cline center positions when migration is high relative to fitness costs, but X- and Y-centers always coincide strictly. X-autosome and Y-autosome incompatibilities also generate steep clines, but systematic shifts in cline centers occur when migration is high relative to selection, as a result of a dominance drive linked to Darwin's corollary. Interestingly, sex-linked genes always show farther introgression than the associated autosomal genes. We discuss ways of disentangling the potentially confounding effects of sex biases in migration, we compare our results to those of a few documented contact zones, and we stress the need to study independent replicates of the same contact zone.
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Affiliation(s)
- Luca Sciuchetti
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, Lausanne, 1015, Switzerland
| | - Christophe Dufresnes
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, Lausanne, 1015, Switzerland
- Department of Animal & Plant Sciences, University of Sheffield, Alfred Denny building, Western Bank, Sheffield, S10 2TN, United Kingdom
| | - Elisa Cavoto
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, Lausanne, 1015, Switzerland
| | - Alan Brelsford
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, Lausanne, 1015, Switzerland
- Biology Department, University of California, Riverside, CA, 92521
| | - Nicolas Perrin
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, Lausanne, 1015, Switzerland
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27
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Dufresnes C, Lymberakis P, Kornilios P, Savary R, Perrin N, Stöck M. Phylogeography of Aegean green toads (Bufo viridis subgroup): continental hybrid swarm vs. insular diversification with discovery of a new island endemic. BMC Evol Biol 2018; 18:67. [PMID: 29720079 PMCID: PMC5930823 DOI: 10.1186/s12862-018-1179-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 04/16/2018] [Indexed: 11/18/2022] Open
Abstract
Background Debated aspects in speciation research concern the amount of gene flow between incipient species under secondary contact and the modes by which post-zygotic isolation accumulates. Secondary contact zones of allopatric lineages, involving varying levels of divergence, provide natural settings for comparative studies, for which the Aegean (Eastern Mediterranean) geography offers unique scenarios. In Palearctic green toads (Bufo viridis subgroup or Bufotes), Plio-Pleistocene (~ 2.6 Mya) diverged species show a sharp transition without contemporary gene flow, while younger lineages, diverged in the Lower-Pleistocene (~ 1.9 Mya), admix over tens of kilometers. Here, we conducted a fine-scale multilocus phylogeographic analysis of continental and insular green toads from the Aegean, where a third pair of taxa, involving Mid-Pleistocene diverged (~ 1.5 Mya) mitochondrial lineages, earlier tentatively named viridis and variabilis, (co-)occurs. Results We discovered a new lineage, endemic to Naxos (Central Cyclades), while coastal islands and Crete feature weak genetic differentiation from the continent. In continental Greece, both lineages, viridis and variabilis, form a hybrid swarm, involving massive mitochondrial and nuclear admixture over hundreds of kilometers, without obvious selection against hybrids. Conclusions The genetic signatures of insular Aegean toads appear governed by bathymetry and Quaternary sea level changes, resulting in long-term isolation (Central Cyclades: Naxos) and recent land-bridges (coastal islands). Conversely, Crete has been isolated since the end of the Messinian salinity crisis (5.3 My) and Cretan populations thus likely result from human-mediated colonization, at least since Antiquity, from Peloponnese and Anatolia. Comparisons of green toad hybrid zones support the idea that post-zygotic hybrid incompatibilities accumulate gradually over the genome. In this radiation, only one million years of divergence separate a scenario of complete reproductive isolation, from a secondary contact resulting in near panmixia. Electronic supplementary material The online version of this article (10.1186/s12862-018-1179-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christophe Dufresnes
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.,Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK
| | - Petros Lymberakis
- Natural History Museum of Crete, University of Crete, Knosos Av, P.O. Box 2208, 71409, Irakleio, Crete, Greece
| | - Panagiotis Kornilios
- Section of Animal Biology, Department of Biology, School of Natural Sciences, University of Patras, GR-26500, Patras, Greece.,Department of Biology, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA
| | - Romain Savary
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Nicolas Perrin
- Department of Ecology & Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Matthias Stöck
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, D-12587, Berlin, Germany.
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Souissi A, Bonhomme F, Manchado M, Bahri-Sfar L, Gagnaire PA. Genomic and geographic footprints of differential introgression between two divergent fish species (Solea spp.). Heredity (Edinb) 2018; 121:579-593. [PMID: 29713088 DOI: 10.1038/s41437-018-0079-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/12/2018] [Accepted: 03/10/2018] [Indexed: 11/09/2022] Open
Abstract
Investigating gene flow between closely related species and its variation across the genome is important to understand how reproductive barriers shape genome divergence before speciation is complete. An efficient way to characterize differential gene flow is to study how the genetic interactions that take place in hybrid zones selectively filter gene exchange between species, leading to heterogeneous genome divergence. In the present study, genome-wide divergence and introgression patterns were investigated between two sole species, Solea senegalensis and Solea aegyptiaca, using restriction-associated DNA sequencing (RAD-Seq) to analyze samples taken from a transect spanning the hybrid zone. An integrative approach combining geographic and genomic clines methods with an analysis of individual locus introgression accounting for the demographic history of divergence was conducted. Our results showed that the two sole species have come into secondary contact postglacially, after experiencing a prolonged period (ca. 1.1 to 1.8 Myrs) of allopatric separation. Secondary contact resulted in the formation of a tension zone characterized by strong reproductive isolation, which only allowed introgression in a limited fraction of the genome. We found multiple evidence for a preferential direction of introgression in the S. aegyptiaca genetic background, indicating a possible recent or ongoing movement of the hybrid zone. Deviant introgression signals found in the opposite direction suggested that S. senegalensis could have possibly undergone adaptive introgression that has not yet spread throughout the entire species range. Our study thus illustrates the varied outcomes of genetic interactions between divergent gene pools that recently met after a long history of divergence.
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Affiliation(s)
- Ahmed Souissi
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France. .,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France. .,Faculté des Sciences de Tunis UR11ES08 Biologie intégrative et écologie évolutive et fonctionnelle des milieux aquatiques, Université de Tunis El Manar, 2092, Tunis, Tunisia.
| | - François Bonhomme
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France.,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France
| | - Manuel Manchado
- IFAPA Centro El Toruño, Junta de Andalucía, Camino Tiro Pichón s/n, 11500, El Puerto de Santa María, Cádiz, Spain
| | - Lilia Bahri-Sfar
- Faculté des Sciences de Tunis UR11ES08 Biologie intégrative et écologie évolutive et fonctionnelle des milieux aquatiques, Université de Tunis El Manar, 2092, Tunis, Tunisia
| | - Pierre-Alexandre Gagnaire
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France.,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France
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McQuillan MA, Roth TC, Huynh AV, Rice AM. Hybrid chickadees are deficient in learning and memory. Evolution 2018; 72:1155-1164. [PMID: 29578575 DOI: 10.1111/evo.13470] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 02/17/2018] [Indexed: 01/08/2023]
Abstract
Identifying the phenotypes underlying postzygotic reproductive isolation is crucial for fully understanding the evolution and maintenance of species. One potential postzygotic isolating barrier that has rarely been examined is learning and memory ability in hybrids. Learning and memory are important fitness-related traits, especially in scatter-hoarding species, where accurate retrieval of hoarded food is vital for winter survival. Here, we test the hypothesis that learning and memory ability can act as a postzygotic isolating barrier by comparing these traits among two scatter-hoarding songbird species, black-capped (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis), and their naturally occurring hybrids. In an outdoor aviary setting, we find that hybrid chickadees perform significantly worse on an associative learning spatial task and are worse at solving a novel problem compared to both parental species. Deficiencies in learning and memory abilities could therefore contribute to postzygotic reproductive isolation between chickadee species. Given the importance of learning and memory for fitness, our results suggest that these traits may play an important, but as yet overlooked, role in postzygotic reproductive isolation.
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Affiliation(s)
- Michael A McQuillan
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Timothy C Roth
- Department of Psychology, Franklin and Marshall College, Lancaster, Pennsylvania 17603
| | - Alex V Huynh
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Amber M Rice
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
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30
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Irwin DE. Sex chromosomes and speciation in birds and other ZW systems. Mol Ecol 2018; 27:3831-3851. [PMID: 29443419 DOI: 10.1111/mec.14537] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 02/03/2018] [Accepted: 02/06/2018] [Indexed: 01/01/2023]
Abstract
Theory and empirical patterns suggest a disproportionate role for sex chromosomes in evolution and speciation. Focusing on ZW sex determination (females ZW, males ZZ; the system in birds, many snakes, and lepidopterans), I review how evolutionary dynamics are expected to differ between the Z, W and the autosomes, discuss how these differences may lead to a greater role of the sex chromosomes in speciation and use data from birds to compare relative evolutionary rates of sex chromosomes and autosomes. Neutral mutations, partially or completely recessive beneficial mutations, and deleterious mutations under many conditions are expected to accumulate faster on the Z than on autosomes. Sexually antagonistic polymorphisms are expected to arise on the Z, raising the possibility of the spread of preference alleles. The faster accumulation of many types of mutations and the potential for complex evolutionary dynamics of sexually antagonistic traits and preferences contribute to a role for the Z chromosome in speciation. A quantitative comparison among a wide variety of bird species shows that the Z tends to have less within-population diversity and greater between-species differentiation than the autosomes, likely due to both adaptive evolution and a greater rate of fixation of deleterious alleles. The W chromosome also shows strong potential to be involved in speciation, in part because of its co-inheritance with the mitochondrial genome. While theory and empirical evidence suggest a disproportionate role for sex chromosomes in speciation, the importance of sex chromosomes is moderated by their small size compared to the whole genome.
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Affiliation(s)
- Darren E Irwin
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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31
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Betto-Colliard C, Hofmann S, Sermier R, Perrin N, Stöck M. Profound genetic divergence and asymmetric parental genome contributions as hallmarks of hybrid speciation in polyploid toads. Proc Biol Sci 2018; 285:rspb.2017.2667. [PMID: 29436499 PMCID: PMC5829204 DOI: 10.1098/rspb.2017.2667] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 01/17/2018] [Indexed: 01/19/2023] Open
Abstract
The evolutionary causes and consequences of allopolyploidization, an exceptional pathway to instant hybrid speciation, are poorly investigated in animals. In particular, when and why hybrid polyploids versus diploids are produced, and constraints on sources of paternal and maternal ancestors, remain underexplored. Using the Palearctic green toad radiation (including bisexually reproducing species of three ploidy levels) as model, we generate a range-wide multi-locus phylogeny of 15 taxa and present four new insights: (i) at least five (up to seven) distinct allotriploid and allotetraploid taxa have evolved in the Pleistocene; (ii) all maternal and paternal ancestors of hybrid polyploids stem from two deeply diverged nuclear clades (6 Mya, 3.1-9.6 Mya), with distinctly greater divergence than the parental species of diploid hybrids found at secondary contact zones; (iii) allotriploid taxa possess two conspecific genomes and a deeply diverged allospecific one, suggesting that genomic imbalance and divergence are causal for their partly clonal reproductive mode; (iv) maternal versus paternal genome contributions exhibit asymmetry, with the maternal nuclear (and mitochondrial) genome of polyploids always coming from the same clade, and the paternal genome from the other. We compare our findings with similar patterns in diploid/polyploid vertebrates, and suggest deep ancestral divergence as a precondition for successful allopolyploidization.
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Affiliation(s)
- Caroline Betto-Colliard
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Sylvia Hofmann
- Department of Conservation Biology, UFZ Helmholtz-Centre for Environmental Research, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Roberto Sermier
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Nicolas Perrin
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015 Lausanne, Switzerland
| | - Matthias Stöck
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 301, 12587 Berlin, Germany
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Morales-Rozo A, Tenorio EA, Carling MD, Cadena CD. Origin and cross-century dynamics of an avian hybrid zone. BMC Evol Biol 2017; 17:257. [PMID: 29246108 PMCID: PMC5732383 DOI: 10.1186/s12862-017-1096-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 11/27/2017] [Indexed: 01/07/2023] Open
Abstract
Background Characterizations of the dynamics of hybrid zones in space and time can give insights about traits and processes important in population divergence and speciation. We characterized a hybrid zone between tanagers in the genus Ramphocelus (Aves, Thraupidae) located in southwestern Colombia. We evaluated whether this hybrid zone originated as a result of secondary contact or of primary differentiation, and described its dynamics across time using spatial analyses of molecular, morphological, and coloration data in combination with paleodistribution modeling. Results Models of potential historical distributions based on climatic data and genetic signatures of demographic expansion suggested that the hybrid zone likely originated following secondary contact between populations that expanded their ranges out of isolated areas in the Quaternary. Concordant patterns of variation in phenotypic characters across the hybrid zone and its narrow extent are suggestive of a tension zone, maintained by a balance between dispersal and selection against hybrids. Estimates of phenotypic cline parameters obtained using specimens collected over nearly a century revealed that, in recent decades, the zone appears to have moved to the east and to higher elevations, and may have become narrower. Genetic variation was not clearly structured along the hybrid zone, but comparisons between historical and contemporary specimens suggested that temporal changes in its genetic makeup may also have occurred. Conclusions Our data suggest that the hybrid zone likey resulted from secondary contact between populations. The observed changes in the hybrid zone may be a result of sexual selection, asymmetric gene flow, or environmental change. Electronic supplementary material The online version of this article (doi: 10.1186/s12862-017-1096-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea Morales-Rozo
- Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.,Programa de Biología y Museo de Historia Natural, Universidad de los Llanos, Sede Barcelona, Villavicencio, Colombia
| | - Elkin A Tenorio
- Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.,Calima: Fundación para la Investigación de la Biodiversidad y Conservación en el Trópico, Cali, Colombia
| | - Matthew D Carling
- Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY, USA.,Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Carlos Daniel Cadena
- Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.
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Garcia-Elfring A, Barrett RDH, Combs M, Davies TJ, Munshi-South J, Millien V. Admixture on the northern front: population genomics of range expansion in the white-footed mouse (Peromyscus leucopus) and secondary contact with the deer mouse (Peromyscus maniculatus). Heredity (Edinb) 2017; 119:447-458. [PMID: 28902189 PMCID: PMC5677999 DOI: 10.1038/hdy.2017.57] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 06/29/2017] [Indexed: 01/03/2023] Open
Abstract
Range expansion has genetic consequences expected to result in differentiated wave-front populations with low genetic variation and potentially introgression from a local species. The northern expansion of Peromyscus leucopus in southern Quebec provides an opportunity to test these predictions using population genomic tools. Our results show evidence of recent and post-glacial expansion. Genome-wide variation in P. leucopus indicates two post-glacial lineages are separated by the St. Lawrence River, with a more recent divergence of populations isolated by the Richelieu River. In two of three transects we documented northern populations with low diversity in at least one genetic measure, although most relationships were not significant. Consistent with bottlenecks and allele surfing during northward expansion, we document a northern-most population with low nucleotide diversity, divergent allele frequencies and the most private alleles, and observed heterozygosity indicates outcrossing. Ancestry proportions revealed putative hybrids of P. leucopus and P. maniculatus. A formal test for gene flow confirmed secondary contact, showing that a reticulate population phylogeny between P. maniculatus and P. leucopus was a better fit to the data than a bifurcating model without gene flow. Thus, we provide the first genomic evidence of gene flow between this pair of species in natural populations. Understanding the evolutionary consequences of secondary contact is an important conservation concern as climate-induced range expansions are expected to result in new hybrid zones between closely related species.
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Affiliation(s)
- A Garcia-Elfring
- Redpath Museum, McGill University, Montreal, QC, Canada
- Department of Biology, McGill University, Montreal, QC, Canada
| | - R D H Barrett
- Redpath Museum, McGill University, Montreal, QC, Canada
| | - M Combs
- Louis Calder Center, Biological Field Station, Fordham University, Armonk, NY, USA
| | - T J Davies
- Department of Biology, McGill University, Montreal, QC, Canada
| | - J Munshi-South
- Louis Calder Center, Biological Field Station, Fordham University, Armonk, NY, USA
| | - V Millien
- Redpath Museum, McGill University, Montreal, QC, Canada
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35
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Fouet C, Kamdem C, Gamez S, White BJ. Genomic insights into adaptive divergence and speciation among malaria vectors of the Anopheles nili group. Evol Appl 2017; 10:897-906. [PMID: 29151881 PMCID: PMC5680430 DOI: 10.1111/eva.12492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/27/2017] [Indexed: 01/16/2023] Open
Abstract
Ongoing speciation in the most important African malaria vectors gives rise to cryptic populations, which differ remarkably in their behavior, ecology, and capacity to vector malaria parasites. Understanding the population structure and the drivers of genetic differentiation among mosquitoes is crucial for effective disease control because heterogeneity within vector species contributes to variability in malaria cases and allow fractions of populations to escape control efforts. To examine population structure and the potential impacts of recent large-scale control interventions, we have investigated the genomic patterns of differentiation in mosquitoes belonging to the Anopheles nili group-a large taxonomic group that diverged ~3 Myr ago. Using 4,343 single nucleotide polymorphisms (SNPs), we detected strong population structure characterized by high-FST values between multiple divergent populations adapted to different habitats within the Central African rainforest. Delineating the cryptic species within the Anopheles nili group is challenging due to incongruence between morphology, ribosomal DNA, and SNP markers consistent with incomplete lineage sorting and/or interspecific gene flow. A very high proportion of loci are fixed (FST = 1) within the genome of putative species, which suggests that ecological and/or reproductive barriers are maintained by strong selection on a substantial number of genes.
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Affiliation(s)
- Caroline Fouet
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Colince Kamdem
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Stephanie Gamez
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Bradley J. White
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
- Center for Disease Vector ResearchInstitute for Integrative Genome BiologyUniversity of CaliforniaRiversideCAUSA
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36
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Wagner CE, Mandeville EG. Speciation, species persistence and the goals of studying genomic barriers to gene flow. J Evol Biol 2017; 30:1512-1515. [DOI: 10.1111/jeb.13112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 01/06/2023]
Affiliation(s)
- C. E. Wagner
- Department of Botany University of Wyoming Laramie WY USA
- Biodiversity Institute University of Wyoming Laramie WY USA
| | - E. G. Mandeville
- Department of Botany University of Wyoming Laramie WY USA
- Wyoming Cooperative Fish and Wildlife Research Unit University of Wyoming Laramie WY USA
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37
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Visser M, de Leeuw M, Zuiderwijk A, Arntzen JW. Stabilization of a salamander moving hybrid zone. Ecol Evol 2016; 7:689-696. [PMID: 28116063 PMCID: PMC5243777 DOI: 10.1002/ece3.2676] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/14/2016] [Indexed: 01/05/2023] Open
Abstract
When related species meet upon postglacial range expansion, hybrid zones are frequently formed. Theory predicts that such zones may move over the landscape until equilibrium conditions are reached. One hybrid zone observed to be moving in historical times (1950–1979) is that of the pond‐breeding salamanders Triturus cristatus and Triturus marmoratus in western France. We identified the ecological correlates of the species hybrid zone as elevation, forestation, and hedgerows favoring the more terrestrial T. marmoratus and pond density favoring the more aquatic T. cristatus. The past movement of the zone of ca. 30 km over three decades has probably been driven by the drastic postwar reduction of the “bocage” hedgerow landscape, favoring T. cristatus over T. marmoratus. No further hybrid zone movement was observed from 1979 to the present. To explain the changing dynamics of the hybrid zone, we propose that it stalled, either because an equilibrium was found at an altitude of ca. 140 m a.s.l. or due to pond loss and decreased population densities. While we cannot rule out the former explanation, we found support for the latter. Under agricultural intensification, ponds in the study area are lost at an unprecedented rate of 5.5% per year, so that remaining Triturus populations are increasingly isolated, hampering dispersal and further hybrid zone movement.
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Affiliation(s)
| | | | | | - Jan W Arntzen
- Naturalis Biodiversity Center Leiden The Netherlands
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38
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Grossen C, Seneviratne SS, Croll D, Irwin DE. Strong reproductive isolation and narrow genomic tracts of differentiation among three woodpecker species in secondary contact. Mol Ecol 2016; 25:4247-66. [DOI: 10.1111/mec.13751] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 06/25/2016] [Accepted: 06/27/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Christine Grossen
- Department of Zoology and Biodiversity Research Centre; University of British Columbia; 6270 University Blvd. Vancouver BC V6T 1Z4 Canada
- Institute of Evolutionary Biology and Environmental Studies; University of Zürich; Winterthurerstrasse 190 CH-8057 Zürich Switzerland
| | - Sampath S. Seneviratne
- Department of Zoology and Biodiversity Research Centre; University of British Columbia; 6270 University Blvd. Vancouver BC V6T 1Z4 Canada
- Avian Evolution Node; Department of Zoology; University of Colombo; PO Box 1490 Colombo 03 Sri Lanka
| | - Daniel Croll
- Integrative Biology; ETH Zürich; Universitätstrasse 2 CH-8092 Zürich Switzerland
| | - Darren E. Irwin
- Department of Zoology and Biodiversity Research Centre; University of British Columbia; 6270 University Blvd. Vancouver BC V6T 1Z4 Canada
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Harrison RG, Larson EL. Heterogeneous genome divergence, differential introgression, and the origin and structure of hybrid zones. Mol Ecol 2016; 25:2454-66. [PMID: 26857437 DOI: 10.1111/mec.13582] [Citation(s) in RCA: 153] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/19/2016] [Accepted: 01/25/2016] [Indexed: 12/16/2022]
Abstract
Hybrid zones have been promoted as windows on the evolutionary process and as laboratories for studying divergence and speciation. Patterns of divergence between hybridizing species can now be characterized on a genomewide scale, and recent genome scans have focused on the presence of 'islands' of divergence. Patterns of heterogeneous genomic divergence may reflect differential introgression following secondary contact and provide insights into which genome regions contribute to local adaptation, hybrid unfitness and positive assortative mating. However, heterogeneous genome divergence can also arise in the absence of any gene flow, as a result of variation in selection and recombination across the genome. We suggest that to understand hybrid zone origins and dynamics, it is essential to distinguish between genome regions that are divergent between pure parental populations and regions that show restricted introgression where these populations interact in hybrid zones. The latter, more so than the former, reveal the likely genetic architecture of reproductive isolation. Mosaic hybrid zones, because of their complex structure and multiple contacts, are particularly good subjects for distinguishing primary intergradation from secondary contact. Comparisons among independent hybrid zones or transects that involve the 'same' species pair can also help to distinguish between divergence with gene flow and secondary contact. However, data from replicate hybrid zones or replicate transects do not reveal consistent patterns; in a few cases, patterns of introgression are similar across independent transects, but for many taxa, there is distinct lack of concordance, presumably due to variation in environmental context and/or variation in the genetics of the interacting populations.
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Affiliation(s)
- Richard G Harrison
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Erica L Larson
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
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40
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Mao X, Zhang S, Rossiter SJ. Differential introgression suggests candidate beneficial and barrier loci between two parapatric subspecies of Pearson's horseshoe bat Rhinolophus pearsoni. Curr Zool 2016; 62:405-412. [PMID: 29491929 PMCID: PMC5829442 DOI: 10.1093/cz/zow017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 10/05/2015] [Indexed: 11/13/2022] Open
Abstract
Observations that rates of introgression between taxa can vary across loci are
increasingly common. Here, we test for differential locus-wise introgression in 2
parapatric subspecies of Pearson′s horseshoe bat (Rhinolophus pearsoni
chinensis and R. p. pearsoni). To efficiently identify
putative speciation genes and/or beneficial genes in our current system, we used a
candidate gene approach by including loci from X chromosome that are suggested to be more
likely involved in reproductive isolation in other organisms and loci underlying hearing
that have been suggested to spread across the hybrid zone in another congeneric species.
Phylogenetic and coalescent analyses were performed at 2 X-linked, 4 hearing genes, as
well as 2 other autosomal loci individually. Likelihood ratio tests could not reject the
model of zero gene flow at 2 X-linked and 2 autosomal genes. In contrast, gene flow was
supported at 3 of 4 hearing genes. While this introgression could be adaptive, we cannot
rule out stochastic processes. Our results highlight the utility of the candidate gene
approach in searching for speciation genes and/or beneficial genes across the species
boundary in natural populations.
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Affiliation(s)
- Xiuguang Mao
- Institute of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China and.,School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
| | - Shuyi Zhang
- Institute of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China and
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
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41
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Empirical evidence for large X-effects in animals with undifferentiated sex chromosomes. Sci Rep 2016; 6:21029. [PMID: 26868373 PMCID: PMC4751523 DOI: 10.1038/srep21029] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/15/2016] [Indexed: 02/03/2023] Open
Abstract
Reproductive isolation is crucial for the process of speciation to progress. Sex chromosomes have been assigned a key role in driving reproductive isolation but empirical evidence from natural population processes has been restricted to organisms with degenerated sex chromosomes such as mammals and birds. Here we report restricted introgression at sex-linked compared to autosomal markers in a hybrid zone between two incipient species of European tree frog, Hyla arborea and H. orientalis, whose homologous X and Y sex chromosomes are undifferentiated. This large X-effect cannot result from the dominance or faster-X aspects of Haldane's rule, which are specific to degenerated sex chromosomes, but rather supports a role for faster-heterogametic-sex or faster-male evolutionary processes. Our data suggest a prominent contribution of undifferentiated sex chromosomes to speciation.
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42
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Lozier JD, Jackson JM, Dillon ME, Strange JP. Population genomics of divergence among extreme and intermediate color forms in a polymorphic insect. Ecol Evol 2016; 6:1075-91. [PMID: 26811748 PMCID: PMC4722823 DOI: 10.1002/ece3.1928] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 01/01/2023] Open
Abstract
Geographic variation in insect coloration is among the most intriguing examples of rapid phenotypic evolution and provides opportunities to study mechanisms of phenotypic change and diversification in closely related lineages. The bumble bee Bombus bifarius comprises two geographically disparate color groups characterized by red‐banded and black‐banded abdominal pigmentation, but with a range of spatially and phenotypically intermediate populations across western North America. Microsatellite analyses have revealed that B. bifarius in the USA are structured into two major groups concordant with geography and color pattern, but also suggest ongoing gene flow among regional populations. In this study, we better resolve the relationships among major color groups to better understand evolutionary mechanisms promoting and maintaining such polymorphism. We analyze >90,000 and >25,000 single‐nucleotide polymorphisms derived from transcriptome (RNAseq) and double digest restriction site associated DNA sequencing (ddRAD), respectively, in representative samples from spatial and color pattern extremes in B. bifarius as well as phenotypic and geographic intermediates. Both ddRAD and RNAseq data illustrate substantial genome‐wide differentiation of the red‐banded (eastern) color form from both black‐banded (western) and intermediate (central) phenotypes and negligible differentiation among the latter populations, with no obvious admixture among bees from the two major lineages. Results thus indicate much stronger background differentiation among B. bifarius lineages than expected, highlighting potential challenges for revealing loci underlying color polymorphism from population genetic data alone. These findings will have significance for resolving taxonomic confusion in this species and in future efforts to investigate color‐pattern evolution in B. bifarius and other polymorphic bumble bee species.
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Affiliation(s)
- Jeffrey D Lozier
- Department of Biological Sciences University of Alabama Tuscaloosa Alabama
| | - Jason M Jackson
- Department of Biological Sciences University of Alabama Tuscaloosa Alabama
| | - Michael E Dillon
- Department of Zoology & Physiology and Program in Ecology University of Wyoming Laramie Wyoming
| | - James P Strange
- USDA-ARS Pollinating Insect Research Unit Utah State University Logan Utah
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Manthey JD, Robbins MB, Moyle RG. A genomic investigation of the putative contact zone between divergent Brown Creeper (Certhia americana) lineages: chromosomal patterns of genetic differentiation. Genome 2015; 59:115-25. [PMID: 26794151 DOI: 10.1139/gen-2015-0093] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sky islands, or montane forest separated by different lowland habitats, are highly fragmented regions that potentially limit gene flow between isolated populations. In the sky islands of the Madrean Archipelago (Arizona, USA), various taxa display different phylogeographic patterns, from unrestricted gene flow among sky islands to complex patterns with multiple distinct lineages. Using genomic-level approaches allows the investigation of differential patterns of gene flow, selection, and genetic differentiation among chromosomes and specific genomic regions between sky island populations. Here, we used thousands of SNPs to investigate the putative contact zone of divergent Brown Creeper (Certhia americana) lineages in the Madrean Archipelago sky islands. We found the two lineages to be completely allopatric (during the breeding season) with a lack of hybridization and gene flow between lineages and no genetic structure among sky islands within lineages. Additionally, the two lineages inhabit different climatic and ecosystem conditions and have many local primary song dialects in the southern Arizona mountain ranges. We identified a positive relationship between genetic differentiation and chromosome size, but the sex chromosome (Z) was not found to be an outlier. Differential patterns of genetic differentiation per chromosome may be explained by genetic drift--possibly in conjunction with non-random mating and non-random gene flow--due to variance in recombination rates among chromosomes.
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Affiliation(s)
- Joseph D Manthey
- a Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA.,b Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA
| | - Mark B Robbins
- a Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA
| | - Robert G Moyle
- a Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA.,b Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA
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McQuillan MA, Rice AM. Differential effects of climate and species interactions on range limits at a hybrid zone: potential direct and indirect impacts of climate change. Ecol Evol 2015; 5:5120-37. [PMID: 26640687 PMCID: PMC4662315 DOI: 10.1002/ece3.1774] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/08/2015] [Accepted: 09/17/2015] [Indexed: 01/20/2023] Open
Abstract
The relative contributions of climate versus interspecific interactions in shaping species distributions have important implications for closely related species at contact zones. When hybridization occurs within a contact zone, these factors regulate hybrid zone location and movement. While a hybrid zone's position may depend on both climate and interactions between the hybridizing species, little is known about how these factors interact to affect hybrid zone dynamics. Here, we utilize SDM (species distribution modeling) both to characterize the factors affecting the current location of a moving North American avian hybrid zone and to predict potential direct and indirect effects of climate change on future distributions. We focus on two passerine species that hybridize where their ranges meet, the Black‐capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee. Our contemporary climate models predict the occurrence of climatically suitable habitat extending beyond the hybrid zone for P. atricapillus only, suggesting that interspecific interactions primarily regulate this range boundary in P. atricapillus, while climatic factors regulate P. carolinensis. Year 2050 climate models predict a drastic northward shift in suitable habitat for P. carolinensis. Because of the greater importance of interspecific interactions for regulating the southern range limit of P. atricapillus, these climate‐mediated shifts in the distribution of P. carolinensis may indirectly lead to a range retraction in P. atricapillus. Together, our results highlight the ways climate change can both directly and indirectly affect species distributions and hybrid zone location. In addition, our study lends support to the longstanding hypothesis that abiotic factors regulate species' poleward range limits, while biotic factors shape equatorial range limits.
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Affiliation(s)
- Michael A McQuillan
- Department of Biological Sciences Lehigh University 111 Research Drive Bethlehem Pennsylvania 18015
| | - Amber M Rice
- Department of Biological Sciences Lehigh University 111 Research Drive Bethlehem Pennsylvania 18015
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Dierickx EG, Shultz AJ, Sato F, Hiraoka T, Edwards SV. Morphological and genomic comparisons of Hawaiian and Japanese Black-footed Albatrosses (Phoebastria nigripes) using double digest RADseq: implications for conservation. Evol Appl 2015; 8:662-78. [PMID: 26240604 PMCID: PMC4516419 DOI: 10.1111/eva.12274] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 04/14/2015] [Indexed: 01/01/2023] Open
Abstract
Evaluating the genetic and demographic independence of populations of threatened species is important for determining appropriate conservation measures, but different technologies can yield different conclusions. Despite multiple studies, the taxonomic status and extent of gene flow between the main breeding populations of Black-footed Albatross (Phoebastria nigripes), a Near-Threatened philopatric seabird, are still controversial. Here, we employ double digest RADseq to quantify the extent of genomewide divergence and gene flow in this species. Our genomewide data set of 9760 loci containing 3455 single nucleotide polymorphisms yielded estimates of genetic diversity and gene flow that were generally robust across seven different filtering and sampling protocols and suggest a low level of genomic variation (θ per site = ∼0.00002-0.00028), with estimates of effective population size (N e = ∼500-15 881) falling far below current census size. Genetic differentiation was small but detectable between Japan and Hawaii (F ST ≈ 0.038-0.049), with no F ST outliers. Additionally, using museum specimens, we found that effect sizes of morphological differences by sex or population rarely exceeded 4%. These patterns suggest that the Hawaiian and Japanese populations exhibit small but significant differences and should be considered separate management units, although the evolutionary and adaptive consequences of this differentiation remain to be identified.
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Affiliation(s)
- Elisa G Dierickx
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University Cambridge, MA, USA ; Department of Zoology, University of Cambridge Cambridge, UK
| | - Allison J Shultz
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University Cambridge, MA, USA
| | - Fumio Sato
- Yamashina Institute for Ornithology Abiko, Japan
| | | | - Scott V Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University Cambridge, MA, USA
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Taylor SA, Larson EL, Harrison RG. Hybrid zones: windows on climate change. Trends Ecol Evol 2015; 30:398-406. [PMID: 25982153 DOI: 10.1016/j.tree.2015.04.010] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/16/2015] [Accepted: 04/17/2015] [Indexed: 12/16/2022]
Abstract
Defining the impacts of anthropogenic climate change on biodiversity and species distributions is currently a high priority. Niche models focus primarily on predicted changes in abiotic factors; however, species interactions and adaptive evolution will impact the ability of species to persist in the face of changing climate. Our review focuses on the use of hybrid zones to monitor responses of species to contemporary climate change. Monitoring hybrid zones provides insight into how range boundaries shift in response to climate change by illuminating the combined effects of species interactions and physiological sensitivity. At the same time, the semipermeable nature of species boundaries allows us to document adaptive introgression of alleles associated with response to climate change.
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Affiliation(s)
- Scott A Taylor
- Cornell Lab of Ornithology, Fuller Evolutionary Biology Program, Ithaca, NY 14850, USA; Cornell University, Department of Ecology and Evolutionary Biology, Ithaca, NY 14853, USA.
| | - Erica L Larson
- University of Montana, Division of Biological Sciences, Missoula, MT 59812, USA
| | - Richard G Harrison
- Cornell University, Department of Ecology and Evolutionary Biology, Ithaca, NY 14853, USA
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