1
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Alfieri JM, Hingoranee R, Athrey GN, Blackmon H. Domestication is associated with increased interspecific hybrid compatibility in landfowl (order: Galliformes). J Hered 2024; 115:1-10. [PMID: 37769441 PMCID: PMC10838130 DOI: 10.1093/jhered/esad059] [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: 05/16/2023] [Revised: 09/15/2023] [Accepted: 09/26/2023] [Indexed: 09/30/2023] Open
Abstract
Some species are able to hybridize despite being exceptionally diverged. The causes of this variation in accumulation of reproductive isolation remain poorly understood, and domestication as an impetus or hindrance to reproductive isolation remains to be characterized. In this study, we investigated the role of divergence time, domestication, and mismatches in morphology, habitat, and clutch size among hybridizing species on reproductive isolation in the bird order Galliformes. We compiled and analyzed hybridization occurrences from literature and recorded measures of postzygotic reproductive isolation. We used a text-mining approach leveraging a historical aviculture magazine to quantify the degree of domestication across species. We obtained divergence time, morphology, habitat, and clutch size data from open sources. We found 123 species pairs (involving 77 species) with known offspring fertility (sterile, only males fertile, or both sexes fertile). We found that divergence time and clutch size were significant predictors of reproductive isolation (McFadden's Pseudo-R2 = 0.59), but not habitat or morphological mismatch. Perhaps most interesting, we found a significant relationship between domestication and reproductive compatibility after correcting for phylogeny, removing extreme values, and addressing potential biases (F1,74 = 5.43, R2 = 0.06, P-value = 0.02). We speculate that the genetic architecture and disruption in selective reproductive regimes associated with domestication may impact reproductive isolation, causing domesticated species to be more reproductively labile.
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Affiliation(s)
- James M Alfieri
- Interdisciplinary Program in Ecology and Evolutionary Biology, Texas A&M University, College Station, TX, USA
- Department of Poultry Science, Texas A&M University, College Station, TX, USA
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Reina Hingoranee
- Department of Epidemiology and Biostatistics, Texas A&M University, College Station, TX, USA
| | - Giridhar N Athrey
- Interdisciplinary Program in Ecology and Evolutionary Biology, Texas A&M University, College Station, TX, USA
- Department of Poultry Science, Texas A&M University, College Station, TX, USA
| | - Heath Blackmon
- Interdisciplinary Program in Ecology and Evolutionary Biology, Texas A&M University, College Station, TX, USA
- Department of Biology, Texas A&M University, College Station, TX, USA
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2
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Rohwer VG, Hagler SJ, Van Doren BM, Fuentes M, Billerman SM. Lower survival of hybrid grosbeaks, but not towhees, suggests a molt divide disfavors hybrids. Evolution 2023; 77:1956-1966. [PMID: 37345673 DOI: 10.1093/evolut/qpad112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 05/29/2023] [Accepted: 06/21/2023] [Indexed: 06/23/2023]
Abstract
Although avian hybrid zones in the Great Plains have been studied for almost 70 years, we know surprisingly little about the fitness costs to hybrids that keep these zones narrow. We compare age ratios in grosbeaks (Pheucticus ludovicianus and P. melanocephalus) and towhees (Pipilo erythropthalums and P. maculatus), two species pairs that differ in their life histories and molt schedules, to evaluate survival between hybrids and parentals. We then contrast molt and migratory divides as possible sources of selection against hybrids. Hybrid grosbeaks had 27%-33% lower survival relative to their parentals, whereas hybrid towhees had survival rates similar to parentals. Age ratio data for hybrid grosbeaks suggest high mortality in older birds, as expected if selection operates after the first year of life. This pattern is consistent with parental species of grosbeaks having contrasting molt schedules relative to migration, suggesting high mortality costs to hybrids driven by molt biology, which are expressed later in life. Contrasts in molt schedules are absent in towhees. While migratory divides may exist for towhees and grosbeaks, the low adult survival of hybrid grosbeaks suggest that molt may be an important and underappreciated source of selection maintaining this and other narrow avian hybrid zones.
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Affiliation(s)
- Vanya G Rohwer
- Cornell University Museum of Vertebrates, Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
| | - Samantha J Hagler
- Cornell University Museum of Vertebrates, Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
- Cornell Lab of Ornithology, Ithaca, NY, United States
| | - Benjamin M Van Doren
- Cornell Lab of Ornithology, Ithaca, NY, United States
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
| | - Miguel Fuentes
- Manning College of Information and Computer Sciences, University of Massachusetts-Amherst, Amherst, MA, United States
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3
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DeRaad DA, McCormack JE, Chen N, Peterson AT, Moyle RG. Combining Species Delimitation, Species Trees, and Tests for Gene Flow Clarifies Complex Speciation in Scrub-Jays. Syst Biol 2022; 71:1453-1470. [PMID: 35552760 DOI: 10.1093/sysbio/syac034] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 05/02/2022] [Accepted: 05/06/2022] [Indexed: 11/13/2022] Open
Abstract
Complex speciation, involving rapid divergence and multiple bouts of post-divergence gene flow, can obfuscate phylogenetic relationships and species limits. In North America, cases of complex speciation are common, due at least in part to the cyclical Pleistocene glacial history of the continent. Scrub-jays in the genus Aphelocoma provide a useful case study in complex speciation because their range throughout North America is structured by phylogeographic barriers with multiple cases of secondary contact between divergent lineages. Here, we show that a comprehensive approach to genomic reconstruction of evolutionary history, i.e., synthesizing results from species delimitation, species tree reconstruction, demographic model testing, and tests for gene flow, is capable of clarifying evolutionary history despite complex speciation. We find concordant evidence across all statistical approaches for the distinctiveness of an endemic southern Mexico lineage (A. w. sumichrasti), culminating in support for the species status of this lineage under any commonly applied species concept. We also find novel genomic evidence for the species status of a Texas endemic lineage A. w. texana, for which equivocal species delimitation results were clarified by demographic modeling and spatially explicit models of gene flow. Finally, we find that complex signatures of both ancient and modern gene flow between the non-sister California Scrub-Jay (A. californica) and Woodhouse's Scrub-Jay (A. woodhouseii), result in discordant gene trees throughout the species' genomes despite clear support for their overall isolation and species status. In sum, we find that a multi-faceted approach to genomic analysis can increase our understanding of complex speciation histories, even in well-studied groups. Given the emerging recognition that complex speciation is relatively commonplace, the comprehensive framework that we demonstrate for interrogation of species limits and evolutionary history using genomic data can provide a necessary roadmap for disentangling the impacts of gene flow and incomplete lineage sorting to better understand the systematics of other groups with similarly complex evolutionary histories.
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Affiliation(s)
- Devon A DeRaad
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence KS, 66045, USA
| | - John E McCormack
- Moore Laboratory of Zoology,Occidental College, Los Angeles, CA, 90041, USA
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, NY, 14627, USA
| | - A Townsend Peterson
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence KS, 66045, USA
| | - Robert G Moyle
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence KS, 66045, USA
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4
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Portinha B, Avril A, Bernasconi C, Helanterä H, Monaghan J, Seifert B, Sousa VC, Kulmuni J, Nouhaud P. Whole-genome analysis of multiple wood ant population pairs supports similar speciation histories, but different degrees of gene flow, across their European ranges. Mol Ecol 2022; 31:3416-3431. [PMID: 35460311 PMCID: PMC9320829 DOI: 10.1111/mec.16481] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 04/07/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022]
Abstract
The application of demographic history modelling and inference to the study of divergence between species has become a cornerstone of speciation genomics. Speciation histories are usually reconstructed by analysing single populations from each species, assuming that the inferred population history represents the actual speciation history. However, this assumption may not be met when species diverge with gene flow, for example, when secondary contact may be confined to specific geographic regions. Here, we tested whether divergence histories inferred from heterospecific populations may vary depending on their geographic locations, using the two wood ant species Formica polyctena and F. aquilonia. We performed whole‐genome resequencing of 20 individuals sampled in multiple locations across the European ranges of both species. Then, we reconstructed the histories of distinct heterospecific population pairs using a coalescent‐based approach. Our analyses always supported a scenario of divergence with gene flow, suggesting that divergence started in the Pleistocene (c. 500 kya) and occurred with continuous asymmetrical gene flow from F. aquilonia to F. polyctena until a recent time, when migration became negligible (2–19 kya). However, we found support for contemporary gene flow in a sympatric pair from Finland, where the species hybridise, but no signature of recent bidirectional gene flow elsewhere. Overall, our results suggest that divergence histories reconstructed from a few individuals may be applicable at the species level. Nonetheless, the geographical context of populations chosen to represent their species should be taken into account, as it may affect estimates of migration rates between species when gene flow is spatially heterogeneous.
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Affiliation(s)
- Beatriz Portinha
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland.,cE3c, Centre for Ecology, Evolution and Environmental changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C2, 1749-016, Lisboa, Portugal
| | - Amaury Avril
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland
| | | | - Heikki Helanterä
- Ecology and Genetics research unit, University of Oulu, PO Box 3000, 90014, Oulu, Finland
| | | | | | - Vitor C Sousa
- cE3c, Centre for Ecology, Evolution and Environmental changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C2, 1749-016, Lisboa, Portugal
| | - Jonna Kulmuni
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
| | - Pierre Nouhaud
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
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5
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Do habitat and elevation promote hybridization during secondary contact between three genetically distinct groups of warbling vireo (Vireo gilvus)? Heredity (Edinb) 2022; 128:352-363. [PMID: 35396350 PMCID: PMC9076831 DOI: 10.1038/s41437-022-00529-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 11/08/2022] Open
Abstract
Following postglacial expansion, secondary contact can occur between genetically distinct lineages. These genetic lineages may be associated with specific habitat or environmental variables and therefore, their distributions in secondary contact could reflect such conditions within these areas. Here we used mtDNA, microsatellite, and morphological data to study three genetically distinct groups of warbling vireo (Vireo gilvus) and investigate the role that elevation and habitat play in their distributions. We studied two main contact zones and within each contact zone, we examined two separate transects. Across the Great Plains contact zone, we found that hybridization between eastern and western groups occurs along a habitat and elevational gradient, whereas hybridization across the Rocky Mountain contact zone was not as closely associated with habitat or elevation. Hybrids in the Great Plains contact zone were more common in transitional areas between deciduous and mixed-wood forests, and at lower elevations (<1000 m). Hybridization patterns were similar along both Great Plains transects indicating that habitat and elevation play a role in hybridization between distinct eastern and western genetic groups. The observed patterns suggest adaptation to different habitats, perhaps originating during isolation in multiple Pleistocene refugia, is facilitating hybridization in areas where habitat types overlap.
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6
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Justen H, Kimmitt AA, Delmore KE. Estimating hybridization rates in the wild: Easier said than done? Evolution 2021; 75:2137-2144. [PMID: 32820532 DOI: 10.1111/evo.14082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 11/30/2022]
Abstract
Hybridization has important effects on the evolutionary trajectories of natural populations but estimates of this process in the wild and at the individual-level are lacking. Justyn et al. attempted to fill this gap using the citizen science database eBird but there are limitations to this approach. Here, we outline and directly test these limitations using literature searches, case studies, and a comparison between eBird and Birds of North America (BNA), a database that documents hybridization using the scientific literature. We use a hybrid zone between Lazuli and Indigo buntings to highlight the importance of considering geographic range when estimating rates of hybridization and two literature searches to show the importance of considering cryptic hybrids (those that cannot be identified using phenotypic traits) when quantifying these rates. We also use BNA and a case study of hybrid White-faced and Glossy Ibises to show that citizen scientists are underreporting hybrids compared with experts. Justyn et al. highlighted an important gap in the literature, but their results likely represent the lower limit of hybridization between birds and a more nuanced interpretation of their results (e.g., considering extrinsic postzygotic selection) is needed.
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Affiliation(s)
- Hannah Justen
- Department of Biology, Texas A&M University, College Station, Texas
| | | | - Kira E Delmore
- Department of Biology, Texas A&M University, College Station, Texas
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7
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McEntee JP, Burleigh JG, Singhal S. Dispersal Predicts Hybrid Zone Widths across Animal Diversity: Implications for Species Borders under Incomplete Reproductive Isolation. Am Nat 2020; 196:9-28. [PMID: 32552108 DOI: 10.1086/709109] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hybrid zones occur as range boundaries for many animal taxa. One model for how hybrid zones form and stabilize is the tension zone model, a version of which predicts that hybrid zone widths are determined by a balance between random dispersal into hybrid zones and selection against hybrids. Here, we examine whether random dispersal and proxies for selection against hybrids (genetic distances between hybridizing pairs) can explain variation in hybrid zone widths across 131 hybridizing pairs of animals. We show that these factors alone can explain ∼40% of the variation in zone width among animal hybrid zones, with dispersal explaining far more of the variation than genetic distances. Patterns within clades were idiosyncratic. Genetic distances predicted hybrid zone widths particularly well for reptiles, while this relationship was opposite tension zone predictions in birds. Last, the data suggest that dispersal and molecular divergence set lower bounds on hybrid zone widths in animals, indicating that there are geographic restrictions on hybrid zone formation. Overall, our analyses reinforce the fundamental importance of dispersal in hybrid zone formation and more generally in the ecology of range boundaries.
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8
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Slager DL, Epperly KL, Ha RR, Rohwer S, Wood C, Van Hemert C, Klicka J. Cryptic and extensive hybridization between ancient lineages of American crows. Mol Ecol 2020; 29:956-969. [PMID: 32034818 DOI: 10.1111/mec.15377] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/30/2019] [Accepted: 02/05/2020] [Indexed: 01/02/2023]
Abstract
Most species and therefore most hybrid zones have historically been defined using phenotypic characters. However, both speciation and hybridization can occur with negligible morphological differentiation. Recently developed genomic tools provide the means to better understand cryptic speciation and hybridization. The Northwestern Crow (Corvus caurinus) and American Crow (Corvus brachyrhynchos) are continuously distributed sister taxa that lack reliable traditional characters for identification. In this first population genomic study of Northwestern and American crows, we use genomic SNPs (nuDNA) and mtDNA to investigate the degree of genetic differentiation between these crows and the extent to which they may hybridize. Our results indicate that American and Northwestern crows have distinct evolutionary histories, supported by two nuDNA ancestry clusters and two 1.1%-divergent mtDNA clades dating to the late Pleistocene, when glacial advances may have isolated crow populations in separate refugia. We document extensive hybridization, with geographic overlap of mtDNA clades and admixture of nuDNA across >900 km of western Washington and western British Columbia. This broad hybrid zone consists of late-generation hybrids and backcrosses, but not recent (e.g., F1) hybrids. Nuclear DNA and mtDNA clines had concordant widths and were both centred in southwestern British Columbia, farther north than previously postulated. Overall, our results suggest a history of reticulate evolution in American and Northwestern crows, perhaps due to recurring neutral expansion(s) from Pleistocene glacial refugia followed by lineage fusion(s). However, we do not rule out a contributing role for more recent potential drivers of hybridization, such as expansion into human-modified habitats.
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Affiliation(s)
- David L Slager
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Kevin L Epperly
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Renee R Ha
- Department of Psychology, University of Washington, Seattle, WA, USA
| | - Sievert Rohwer
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Chris Wood
- Burke Museum of Natural History and Culture, Seattle, WA, USA
| | | | - John Klicka
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
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9
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Tan HZ, Ng EYX, Tang Q, Allport GA, Jansen JJFJ, Tomkovich PS, Rheindt FE. Population genomics of two congeneric Palaearctic shorebirds reveals differential impacts of Quaternary climate oscillations across habitats types. Sci Rep 2019; 9:18172. [PMID: 31796810 PMCID: PMC6890745 DOI: 10.1038/s41598-019-54715-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/08/2019] [Indexed: 02/07/2023] Open
Abstract
Intracontinental biotic divisions across the vast Palaearctic region are not well-characterized. Past research has revealed patterns ranging from a lack of population structure to deep divergences along varied lines of separation. Here we compared biogeographic patterns of two Palaearctic shorebirds with different habitat preferences, Whimbrel (Numenius phaeopus) and Eurasian curlew (N. arquata). Using genome-wide markers from populations across the Palaearctic, we applied a multitude of population genomic and phylogenomic approaches to elucidate population structure. Most importantly, we tested for isolation by distance and visualized barriers and corridors to gene flow. We found shallow Palaearctic population structure in subpolar bog and tundra-breeding whimbrels, consistent with other species breeding at a similarly high latitude, indicating connectivity across the tundra belt, both presently and during southward shifts in periods of global cooling. In contrast, the temperate grassland-breeding Eurasian curlew emerged in three distinct clades corresponding to glacial refugia. Barriers to gene flow coincided with areas of topographic relief in the central Palaearctic for whimbrels and further east for Eurasian curlews. Our findings highlight the interplay of historic and ecological factors in influencing present-day population structure of Palaearctic biota.
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Affiliation(s)
- Hui Zhen Tan
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Elize Ying Xin Ng
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Qian Tang
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore
| | - Gary A Allport
- BirdLife International, The David Attenborough Building, Pembroke Street, Cambridge, CB2 3QZ, UK
| | - Justin J F J Jansen
- Naturalis Biodiversity Center, Leiden, P.O. Box 9517, 2300 RA, Leiden, The Netherlands
| | - Pavel S Tomkovich
- Zoological Museum, Lomonosov Moscow State University, Bolshaya Nikitskaya Str. 2, Moscow, 125009, Russia
| | - Frank E Rheindt
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore, 117558, Singapore.
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10
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Thurman TJ, Szejner-Sigal A, McMillan WO. Movement of a Heliconius hybrid zone over 30 years: A Bayesian approach. J Evol Biol 2019; 32:974-983. [PMID: 31216075 DOI: 10.1111/jeb.13499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/29/2019] [Accepted: 06/10/2019] [Indexed: 11/27/2022]
Abstract
Hybrid zones have long been of interest to biologists as natural laboratories where we can gain insight into the processes of adaptation and speciation. Repeated sampling of individual hybrid zones has been particularly useful in elucidating the dynamic balance between selection and dispersal that maintains most hybrid zones. Here, we revisit a hybrid zone between Heliconius erato butterflies in Panamá for a third time over more than 30 years. We combine a novel Bayesian extension of stepped-cline hybrid zone models with environmental data to understand the genetic and environmental causes of cline dynamics in this species. The cline has continued to move west, likely due to dominance drive, but has slowed and broadened. Environmental analyses suggest that widespread deforestation in Panamá could be leading to decreased avian predation and relaxed selection, causing the observed changes in cline dynamics.
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Affiliation(s)
- Timothy J Thurman
- Smithsonian Tropical Research Institute, Panamá, República de Panamá.,Redpath Museum and Department of Biology, McGill University, Montréal, Québec, Canada
| | - Andre Szejner-Sigal
- Smithsonian Tropical Research Institute, Panamá, República de Panamá.,Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, USA
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Panamá, República de Panamá
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11
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Population divergence and gene flow in two East Asian shorebirds on the verge of speciation. Sci Rep 2019; 9:8546. [PMID: 31189934 PMCID: PMC6561938 DOI: 10.1038/s41598-019-44996-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/07/2019] [Indexed: 12/22/2022] Open
Abstract
Genetic isolation of populations over evolutionary time leads to the formation of independent species. We examined a pair of shorebirds – the Kentish Plover Charadrius alexandrinus and the enigmatic White-faced Plover C. dealbatus – which display strong plumage differentiation, yet show minimal genetic divergence based on previous mitochondrial and microsatellite work. Two scenarios may lead to this situation: (1) they represent clinal or poorly diverged populations with limited genomic differentiation despite substantial plumage variation, or (2) they are diverging taxa at the cusp of speciation, with ongoing limited gene flow obliterating signals of differentiation in traditional genetic markers. We compared the genotypes of 98 plovers (59 Kentish Plovers, 35 White-faced Plovers and 4 genomic hybrids) sampled in eastern Asia and Europe using ddRADSeq to harvest over 8000 genome-wide SNPs. In contrast to previous studies, our analyses revealed two well defined genomic clusters, with limited hybridization and a narrow contact zone. We also uncovered significant differences in bill length and further sex-specific differences in size, which may signal differences in mate choice between Kentish and White-faced Plovers. Our results support the hypothesis that this shorebird duo is on the verge of speciation.
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12
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Hinton JW, Gittleman JL, van Manen FT, Chamberlain MJ. Size-assortative choice and mate availability influences hybridization between red wolves ( Canis rufus) and coyotes ( Canis latrans). Ecol Evol 2018; 8:3927-3940. [PMID: 29721269 PMCID: PMC5916303 DOI: 10.1002/ece3.3950] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 01/09/2018] [Accepted: 01/27/2018] [Indexed: 01/30/2023] Open
Abstract
Anthropogenic hybridization of historically isolated taxa has become a primary conservation challenge for many imperiled species. Indeed, hybridization between red wolves (Canis rufus) and coyotes (Canis latrans) poses a significant challenge to red wolf recovery. We considered seven hypotheses to assess factors influencing hybridization between red wolves and coyotes via pair‐bonding between the two species. Because long‐term monogamy and defense of all‐purpose territories are core characteristics of both species, mate choice has long‐term consequences. Therefore, red wolves may choose similar‐sized mates to acquire partners that behave similarly to themselves in the use of space and diet. We observed multiple factors influencing breeding pair formation by red wolves and found that most wolves paired with similar‐sized conspecifics and wolves that formed congeneric pairs with nonwolves (coyotes and hybrids) were mostly female wolves, the smaller of the two sexes. Additionally, we observed that lower red wolf abundance relative to nonwolves and the absence of helpers increased the probability that wolves consorted with nonwolves. However, successful pairings between red wolves and nonwolves were associated with wolves that maintained small home ranges. Behaviors associated with territoriality are energetically demanding and behaviors (e.g., aggressive interactions, foraging, and space use) involved in maintaining territories are influenced by body size. Consequently, we propose the hypothesis that size disparities between consorting red wolves and coyotes influence positive assortative mating and may represent a reproductive barrier between the two species. We offer that it may be possible to maintain wild populations of red wolves in the presence of coyotes if management strategies increase red wolf abundance on the landscape by mitigating key threats, such as human‐caused mortality and hybridization with coyotes. Increasing red wolf abundance would likely restore selection pressures that increase mean body and home‐range sizes of red wolves and decrease hybridization rates via reduced occurrence of congeneric pairs.
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Affiliation(s)
- Joseph W Hinton
- Warnell School of Forestry and Natural Resources University of Georgia Athens GA USA
| | | | - Frank T van Manen
- U.S. Geological Survey Northern Rocky Mountain Science Center Interagency Grizzly Bear Study Team Bozeman MT USA
| | - Michael J Chamberlain
- Warnell School of Forestry and Natural Resources University of Georgia Athens GA USA
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13
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14
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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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15
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Semenov GA, Scordato ESC, Khaydarov DR, Smith C, Kane NC, Safran RJ. Effects of assortative mate choice on the genomic and morphological structure of a hybrid zone between two bird subspecies. Mol Ecol 2017; 26:6430-6444. [DOI: 10.1111/mec.14376] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 08/15/2017] [Accepted: 09/27/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Georgy A. Semenov
- Department of Ecology & Evolutionary Biology The University of Arizona Tucson AZ USA
- Institute of Systematics and Ecology of Animals Novosibirsk Russia
| | | | | | - Chris C. R. Smith
- Department of Ecology and Evolutionary Biology The University of Colorado Boulder CO USA
| | - Nolan C. Kane
- Department of Ecology and Evolutionary Biology The University of Colorado Boulder CO USA
| | - Rebecca J. Safran
- Department of Ecology and Evolutionary Biology The University of Colorado Boulder CO USA
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16
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Oatley G, De Swardt DH, Nuttall RJ, Crowe TM, Bowie RCK. Phenotypic and genotypic variation across a stable white-eye (Zosterops sp.) hybrid zone in central South Africa. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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17
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Matthews WJ, Turner TF, Osborne MJ. Breakdown of a Hybrid Swarm between Two Darters (Percidae),Etheostoma radiosumandEtheostoma spectabile,with Loss of One Parental Species. COPEIA 2016. [DOI: 10.1643/ce-16-409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Curry CM, Patten MA. Shadow of a doubt: premating and postmating isolating barriers in a temporally complex songbird (Passeriformes: Paridae) hybrid zone. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2126-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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19
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Walsh J, Shriver WG, Olsen BJ, Kovach AI. Differential introgression and the maintenance of species boundaries in an advanced generation avian hybrid zone. BMC Evol Biol 2016; 16:65. [PMID: 27000833 PMCID: PMC4802838 DOI: 10.1186/s12862-016-0635-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/10/2016] [Indexed: 12/31/2022] Open
Abstract
Background Evolutionary processes, including selection and differential fitness, shape the introgression of genetic material across a hybrid zone, resulting in the exchange of some genes but not others. Differential introgression of molecular or phenotypic markers can thus provide insight into factors contributing to reproductive isolation. We characterized patterns of genetic variation across a hybrid zone between two tidal marsh birds, Saltmarsh (Ammodramus caudacutus) and Nelson’s (A. nelsoni) sparrows (n = 286), and compared patterns of introgression among multiple genetic markers and phenotypic traits. Results Geographic and genomic cline analyses revealed variable patterns of introgression among marker types. Most markers exhibited gradual clines and indicated that introgression exceeds the spatial extent of the previously documented hybrid zone. We found steeper clines, indicating strong selection for loci associated with traits related to tidal marsh adaptations, including for a marker linked to a gene region associated with metabolic functions, including an osmotic regulatory pathway, as well as for a marker related to melanin-based pigmentation, supporting an adaptive role of darker plumage (salt marsh melanism) in tidal marshes. Narrow clines at mitochondrial and sex-linked markers also offer support for Haldane’s rule. We detected patterns of asymmetrical introgression toward A. caudacutus, which may be driven by differences in mating strategy or differences in population density between the two species. Conclusions Our findings offer insight into the dynamics of a hybrid zone traversing a unique environmental gradient and provide evidence for a role of ecological divergence in the maintenance of pure species boundaries despite ongoing gene flow. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0635-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jennifer Walsh
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA. .,Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA.
| | - W Gregory Shriver
- Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE, USA
| | - Brian J Olsen
- School of Biology and Ecology, University of Maine, Orono, ME, USA
| | - Adrienne I Kovach
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
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20
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Grant PR, Grant BR. Introgressive hybridization and natural selection in Darwin's finches. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12702] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Peter R. Grant
- Department of Ecology and Evolutionary Biology; Princeton University; Princeton NJ 08544-1003 USA
| | - B. Rosemary Grant
- Department of Ecology and Evolutionary Biology; Princeton University; Princeton NJ 08544-1003 USA
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21
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Graves GR. A primer on the hybrid zone of Jamaican streamertail hummingbirds (Trochilidae:Trochilus). P BIOL SOC WASH 2015. [DOI: 10.2988/0006-324x-128.1.111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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22
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Rosser N, Dasmahapatra KK, Mallet J. Stable Heliconius butterfly hybrid zones are correlated with a local rainfall peak at the edge of the Amazon basin. Evolution 2014; 68:3470-84. [PMID: 25311415 DOI: 10.1111/evo.12539] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 09/29/2014] [Indexed: 11/28/2022]
Abstract
Multilocus clines between Müllerian mimetic races of Heliconius butterflies provide a classic example of the maintenance of hybrid zones and their importance in speciation. Concordant hybrid zones in the mimics Heliconius erato and H. melpomene in northern Peru were carefully documented in the 1980s, and this prior work now permits a historical analysis of the movement or stasis of the zones. Previous work predicted that these zones might be moving toward the Andes due to selective asymmetry. Extensive deforestation and climate change might also be expected to affect the positions and widths of the hybrid zones. We show that the positions and shapes of these hybrid zones have instead remained remarkably stable between 1985 and 2012. The stability of this interaction strongly implicates continued selection, rather than neutral mixing following secondary contact. The stability of cline widths and strong linkage disequilibria (gametic correlation coefficients Rmax = 0.35-0.56 among unlinked loci) over 25 years suggest that mimetic selection pressures on each color pattern locus have remained approximately constant (s ≈ 0.13-0.40 per locus in both species). Exceptionally high levels of precipitation at the edge of the easternmost Andes may act as a population density trough for butterflies, trapping the hybrid zones at the foot of the mountains, and preventing movement. As such, our results falsify one prediction of the Pleistocene Refugium theory: That the ranges of divergent species or subspecies should be centered on regions characterized by maxima of rainfall, with hybrid zones falling in more arid regions between them.
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Affiliation(s)
- Neil Rosser
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, United Kingdom; Department of Biology, University of York, Wentworth Way, York, YO10 5DD, United Kingdom.
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23
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Miller MJ, Lipshutz SE, Smith NG, Bermingham E. Genetic and phenotypic characterization of a hybrid zone between polyandrous Northern and Wattled Jacanas in Western Panama. BMC Evol Biol 2014; 14:227. [PMID: 25394718 PMCID: PMC4237789 DOI: 10.1186/s12862-014-0227-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 10/17/2014] [Indexed: 01/15/2023] Open
Abstract
Background Hybridization provides a unique perspective into the ecological, genetic and behavioral context of speciation. Hybridization is common in birds, but has not yet been reported among bird species with a simultaneously polyandrous mating system; a mating system where a single female defends a harem of males who provide nearly all parental care. Unlike simple polyandry, polyandrous mating is extremely rare in birds, with only 1% of bird species employing this mating system. Although it is classically held that females are “choosy” in avian hybrid systems, nearly-exclusive male parental care raises the possibility that female selection against heterospecific matings might be reduced compared to birds with other mating systems. Results We describe a narrow hybrid zone in southwestern Panama between two polyandrous freshwater waders: Northern Jacana, Jacana spinosa and Wattled Jacana, J. jacana. We document coincident cline centers for three phenotypic traits, mtDNA, and one of two autosomal introns. Cline widths for these six markers varied from seven to 142 km, with mtDNA being the narrowest, and five of the six markers having widths less than 100 km. Cline tails were asymmetrical, with greater introgression of J. jacana traits extending westward into the range of J. spinosa. Likewise, within the hybrid zone, the average hybrid index of phenotypic hybrids was significantly biased towards J. spinosa. Species distribution models indicate that the hybrid zone is located at the edge of a roughly 100 km wide overlap where habitat is predicted to be suitable for both species, with more westerly areas suitable only for spinosa and eastward habitats suitable only for J. jacana. Conclusion The two species of New World jacanas maintain a narrow, and persistent hybrid zone in western Panama. The hybrid zone may be maintained by the behavioral dominance of J. spinosa counterbalanced by unsuitable habitat for J. spinosa east of the contact zone. Although the two parental species are relatively young, mitochondrial cline width was extremely narrow. This result suggests strong selection against maternally-inherited markers, which may indicate either mitonuclear incompatibilities and/or female choice against heterospecific matings typical of avian hybrid systems, despite jacana sex role reversal. Electronic supplementary material The online version of this article (doi:10.1186/s12862-014-0227-7) contains supplementary material, which is available to authorized users.
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24
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Curry CM, Patten MA. Current and Historical Extent of Phenotypic Variation in the Tufted and Black-crested Titmouse (Paridae) Hybrid Zone in the Southern Great Plains. AMERICAN MIDLAND NATURALIST 2014. [DOI: 10.1674/0003-0031-171.2.271] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Dufort MJ, Keith Barker F. Range dynamics, rather than convergent selection, explain the mosaic distribution of red-winged blackbird phenotypes. Ecol Evol 2013; 3:4910-24. [PMID: 24455125 PMCID: PMC3892357 DOI: 10.1002/ece3.859] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 09/26/2013] [Accepted: 09/30/2013] [Indexed: 11/24/2022] Open
Abstract
Geographic distributions of genetic and phenotypic characters can illuminate historical evolutionary processes. In particular, mosaic distributions of phenotypically similar populations can arise from parallel evolution or from irregular patterns of dispersal and colonization by divergent forms. Two phenotypically divergent forms of the red-winged blackbird (Agelaius phoeniceus) show a mosaic phenotypic distribution, with a "bicolored" form occurring disjunctly in California and Mexico. We analyzed the relationships among these bicolored populations and neighboring typical populations, using ∼600 bp of mitochondrial DNA sequence data and 10 nuclear short tandem repeat loci. We find that bicolored populations, although separated by ∼3000 km, are genetically more similar to one other than they are to typical populations separated by ∼400 km. We also find evidence of ongoing gene flow among populations, including some evidence of asymmetric gene flow. We conclude that the current distribution of bicolored forms represents incomplete speciation, where recent asymmetric hybridization with typical A. phoeniceus is dividing the range of a formerly widespread bicolored form. This hypothesis predicts that bicolored forms may suffer extinction by hybridization. Future work will use fine-scaled geographical sampling and nuclear sequence data to test for hybrid origins of currently typical populations and to more precisely quantify the directionality of gene flow.
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Affiliation(s)
- Matthew J Dufort
- Department of Ecology, Evolution and Behavior, University of Minnesota 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108
| | - F Keith Barker
- Department of Ecology, Evolution and Behavior, University of Minnesota 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108 ; Bell Museum of Natural History, University of Minnesota 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, Minnesota, 55108
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26
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Malaney JL, Conroy CJ, Moffitt LA, Spoonhunter HD, Patton JL, Cook JA. Phylogeography of the western jumping mouse (Zapus princeps) detects deep and persistent allopatry with expansion. J Mammal 2013. [DOI: 10.1644/12-mamm-a-006.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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27
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Delmore KE, Brenneman RA, Lei R, Bailey CA, Brelsford A, Louis EE, Johnson SE. Clinal variation in a brown lemur (Eulemur
spp.) hybrid zone: Combining morphological, genetic and climatic data to examine stability. J Evol Biol 2013; 26:1677-90. [DOI: 10.1111/jeb.12178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 02/15/2013] [Accepted: 03/26/2013] [Indexed: 11/27/2022]
Affiliation(s)
- K. E. Delmore
- Department of Anthropology; University of Calgary; Calgary AB Canada
| | - R. A. Brenneman
- Center for Conservation and Research; Omaha's Henry Doorly Zoo; Omaha NE USA
| | - R. Lei
- Center for Conservation and Research; Omaha's Henry Doorly Zoo; Omaha NE USA
| | - C. A. Bailey
- Center for Conservation and Research; Omaha's Henry Doorly Zoo; Omaha NE USA
| | - A. Brelsford
- Department of Ecology and Evolution; University of Lausanne; Lausanne Switzerland
| | - E. E. Louis
- Center for Conservation and Research; Omaha's Henry Doorly Zoo; Omaha NE USA
| | - S. E. Johnson
- Department of Anthropology; University of Calgary; Calgary AB Canada
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28
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Smith KL, Hale JM, Gay L, Kearney M, Austin JJ, Parris KM, Melville J. SPATIO-TEMPORAL CHANGES IN THE STRUCTURE OF AN AUSTRALIAN FROG HYBRID ZONE: A 40-YEAR PERSPECTIVE. Evolution 2013; 67:3442-54. [DOI: 10.1111/evo.12140] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 03/24/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Katie L. Smith
- Sciences Department; Museum Victoria; Melbourne VIC 3001 Australia
- Department of Zoology; University of Melbourne; VIC 3010 Australia
- Department of Botany; University of Melbourne; VIC 3010 Australia
| | - Joshua M. Hale
- Sciences Department; Museum Victoria; Melbourne VIC 3001 Australia
- Department of Zoology; University of Melbourne; VIC 3010 Australia
- Department of Botany; University of Melbourne; VIC 3010 Australia
| | - Laurène Gay
- Diversity and Adaptation of Mediterranean Species; UMR AGAP 1334, 2 place Pierre Viala; 34060 Montpellier France
| | - Michael Kearney
- Department of Zoology; University of Melbourne; VIC 3010 Australia
| | - Jeremy J. Austin
- Sciences Department; Museum Victoria; Melbourne VIC 3001 Australia
- Australian Centre for Ancient DNA, School of Earth and Environmental Sciences; University of Adelaide, North Terrace; Adelaide SA 5005 Australia
| | | | - Jane Melville
- Sciences Department; Museum Victoria; Melbourne VIC 3001 Australia
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29
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Is gene flow promoting the reversal of pleistocene divergence in the Mountain Chickadee (Poecile gambeli)? PLoS One 2012; 7:e49218. [PMID: 23152877 PMCID: PMC3495768 DOI: 10.1371/journal.pone.0049218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/05/2012] [Indexed: 01/19/2023] Open
Abstract
The Pleistocene glacial cycles left a genetic legacy on taxa throughout the world; however, the persistence of genetic lineages that diverged during these cycles is dependent upon levels of gene flow and introgression. The consequences of secondary contact among taxa may reveal new insights into the history of the Pleistocene’s genetic legacy. Here, we use phylogeographic methods, using 20 nuclear loci from regional populations, to infer the consequences of secondary contact following divergence in the Mountain Chickadee (Poecile gambeli). Analysis of nuclear data identified two geographically-structured genetic groups, largely concordant with results from a previous mitochondrial DNA (mtDNA) study. Additionally, the estimated multilocus divergence times indicate a Pleistocene divergence, and are highly concordant with mtDNA. The previous mtDNA study showed a paucity of sympatry between clades, while nuclear patterns of gene flow show highly varied patterns between populations. The observed pattern of gene flow, from coalescent-based analyses, indicates southern populations in both clades exhibit little gene flow within or between clades, while northern populations are experiencing higher gene flow within and between clades. If this pattern were to persist, it is possible the historical legacy of Pleistocene divergence may be preserved in the southern populations only, and the northern populations would become a genetically diverse hybrid species.
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30
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Jacobsen F, Omland KE. Extensive introgressive hybridization within the northern oriole group (Genus Icterus) revealed by three-species isolation with migration analysis. Ecol Evol 2012; 2:2413-29. [PMID: 23145328 PMCID: PMC3492769 DOI: 10.1002/ece3.365] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 07/30/2012] [Accepted: 07/31/2012] [Indexed: 12/18/2022] Open
Abstract
Until recently, studies of divergence and gene flow among closely-related taxa were generally limited to pairs of sister taxa. However, organisms frequently exchange genes with other non-sister taxa. The “northern oriole” group within genus Icterus exemplifies this problem. This group involves the extensively studied hybrid zone between Baltimore oriole (Icterus galbula) and Bullock's oriole (I. bullockii), an alleged hybrid zone between I. bullockii and black-backed oriole (I. abeillei), and likely mtDNA introgression between I. galbula and I. abeillei. Here, we examine the divergence population genetics of the entire northern oriole group using a multipopulation Isolation-with-Migration (IM) model. In accordance with Haldane's rule, nuclear loci introgress extensively beyond the I. galbula–I. bullockii hybrid zone, while mtDNA does not. We found no evidence of introgression between I. bullockii and I. abeillei or between I. galbula and I. abeillei when all three species were analyzed together in a three-population model. However, traditional pairwise analysis suggested some nuclear introgression from I. abeillei into I. galbula, probably reflecting genetic contributions from I. bullockii unaccounted for in a two-population model. Thus, only by including all members of this group in the analysis was it possible to rigorously estimate the level of gene flow among these three closely related species.
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Affiliation(s)
- Frode Jacobsen
- Department of Biological Sciences, University of Maryland Baltimore County 1000 Hilltop Circle, Baltimore, MD, 21250, USA
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31
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Singhal S, Moritz C. Strong selection against hybrids maintains a narrow contact zone between morphologically cryptic lineages in a rainforest lizard. Evolution 2012; 66:1474-89. [PMID: 22519785 DOI: 10.1111/j.1558-5646.2011.01539.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phenotypically cryptic lineages comprise an important yet understudied part of biodiversity; in particular, we have much to learn about how these lineages are formed and maintained. To better understand the evolutionary significance of such lineages, we studied a hybrid zone between two morphologically cryptic phylogeographic lineages in the rainforest lizard, Lampropholis coggeri. Analyzing a multilocus genetic dataset through cline inference, individual-based methods and population measures of disequilibrium and using simulations to explore our genetic results in context of theoretical expectations, we inferred the processes maintaining this hybrid zone. We find that these lineages meet in a hybrid zone that is narrow (≈400 m) relative to inferred dispersal rate. Further, the hybrid zone exhibits substantial genetic disequilibrium and sharply coincident and largely concordant clines. Based on our knowledge about the region's biogeography, the species' natural history, and our simulation results, we suggest that strong selection against hybrids structures this system. As all clines show a relatively narrow range of introgression, we posit that this hybrid zone might not yet be in equilibrium. Nonetheless, our results clearly show that phylogeographic lineages can evolve substantial reproductive isolation without concomitant morphological diversification, suggesting that such lineages can constitute a significant component of evolutionary diversity.
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Affiliation(s)
- Sonal Singhal
- Museum of Vertebrate Zoology, University of California, Berkeley, California 94720-3160, USA.
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32
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CONROY CHRISJ, GUPTA ADITIM. Cranial morphology of the California vole (Microtus californicus, Cricetidae) in a contact zone. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01722.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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