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Ji J, Jackson DJ, Leaché AD, Yang Z. Power of Bayesian and Heuristic Tests to Detect Cross-Species Introgression with Reference to Gene Flow in the Tamias quadrivittatus Group of North American Chipmunks. Syst Biol 2023; 72:446-465. [PMID: 36504374 PMCID: PMC10275556 DOI: 10.1093/sysbio/syac077] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 11/15/2022] [Accepted: 12/01/2022] [Indexed: 10/25/2023] Open
Abstract
In the past two decades, genomic data have been widely used to detect historical gene flow between species in a variety of plants and animals. The Tamias quadrivittatus group of North America chipmunks, which originated through a series of rapid speciation events, are known to undergo massive amounts of mitochondrial introgression. Yet in a recent analysis of targeted nuclear loci from the group, no evidence for cross-species introgression was detected, indicating widespread cytonuclear discordance. The study used the heuristic method HYDE to detect gene flow, which may suffer from low power. Here we use the Bayesian method implemented in the program BPP to re-analyze these data. We develop a Bayesian test of introgression, calculating the Bayes factor via the Savage-Dickey density ratio using the Markov chain Monte Carlo (MCMC) sample under the model of introgression. We take a stepwise approach to constructing an introgression model by adding introgression events onto a well-supported binary species tree. The analysis detected robust evidence for multiple ancient introgression events affecting the nuclear genome, with introgression probabilities reaching 63%. We estimate population parameters and highlight the fact that species divergence times may be seriously underestimated if ancient cross-species gene flow is ignored in the analysis. We examine the assumptions and performance of HYDE and demonstrate that it lacks power if gene flow occurs between sister lineages or if the mode of gene flow does not match the assumed hybrid-speciation model with symmetrical population sizes. Our analyses highlight the power of likelihood-based inference of cross-species gene flow using genomic sequence data. [Bayesian test; BPP; chipmunks; introgression; MSci; multispecies coalescent; Savage-Dickey density ratio.].
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Affiliation(s)
- Jiayi Ji
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Donavan J Jackson
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Box 351800, Seattle, WA 98195-1800, USA
| | - Adam D Leaché
- Department of Biology and Burke Museum of Natural History and Culture, University of Washington, Box 351800, Seattle, WA 98195-1800, USA
| | - Ziheng Yang
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
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2
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Herrera ND, Bell KC, Callahan CM, Nordquist E, Sarver BAJ, Sullivan J, Demboski JR, Good JM. Genomic resolution of cryptic species diversity in chipmunks. Evolution 2022; 76:2004-2019. [PMID: 35778920 DOI: 10.1111/evo.14546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 01/22/2023]
Abstract
Discovery of cryptic species is essential to understand the process of speciation and assessing the impacts of anthropogenic stressors. Here, we used genomic data to test for cryptic species diversity within an ecologically well-known radiation of North American rodents, western chipmunks (Tamias). We assembled a de novo reference genome for a single species (Tamias minimus) combined with new and published targeted sequence-capture data for 21,551 autosomal and 493 X-linked loci sampled from 121 individuals spanning 22 species. We identified at least two cryptic lineages corresponding with an isolated subspecies of least chipmunk (T. minimus grisescens) and with a restricted subspecies of the yellow-pine chipmunk (Tamias amoenus cratericus) known only from around the extensive Craters of the Moon lava flow. Additional population-level sequence data revealed that the so-called Crater chipmunk is a distinct species that is abundant throughout the coniferous forests of southern Idaho. This cryptic lineage does not appear to be most closely related to the ecologically and phenotypically similar yellow-pine chipmunk but does show evidence for recurrent hybridization with this and other species.
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Affiliation(s)
- Nathanael D Herrera
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Kayce C Bell
- Natural History Museum of Los Angeles County, Los Angeles, California, USA
| | - Colin M Callahan
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Erin Nordquist
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Brice A J Sarver
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Jack Sullivan
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA.,Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, Idaho, USA
| | - John R Demboski
- Department of Zoology, Denver Museum of Nature & Sciences, Denver, Colorado, USA
| | - Jeffrey M Good
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA.,Wildlife Biology Program, University of Montana, Missoula, Montana, USA
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Brandler OV, Kapustina SY, Nikol’skii AA, Kolesnikov VV, Badmaev BB, Adiya Y. A Study of Hybridization Between Marmota baibacina and M. sibirica in Their Secondary Contact Zone in Mongolian Altai. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.555341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The role of hybridization as one of the factors of speciation in mammals has been underestimated for a long time, but now there is a lot of data on its impact in mammalian evolution. Hybridization of species often occurs in their secondary contact zones, which is a natural model for testing factors that ensure species integrity. Studies of hybrid zones are increasingly revealing the essential role of ecological and behavioral features both in initiating crossbreeding and in maintaining interspecific barriers. We studied the hybridization of two species of marmots Marmota baibacina and M. sibirica in the zone of sympatry in Mongolian Altai Mountains. We used a bioacoustic approach to determine the localization of individuals of different species and their cohabitation sites. Genetic typing with two diploid nuclear markers and one marker each of paternal and maternal lines was used to identify hybrids. Habitat preferences of marmots were studied to understand the conditions for the formation of heterospecific pairs. We found a high proportion of hybrid individuals in boulder screes where conditions for the formation of heterospecific pairs probably exist. Our data indicate the viability and fertility of F1 hybrids and their descendants. We hypothesize that the environmental preferences and behavioral features of both species of marmots are important factors that both create conditions for hybridization and limit hybrid dispersal.
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Sarver BAJ, Herrera ND, Sneddon D, Hunter SS, Settles ML, Kronenberg Z, Demboski JR, Good JM, Sullivan J. Diversification, Introgression, and Rampant Cytonuclear Discordance in Rocky Mountains Chipmunks (Sciuridae: Tamias). Syst Biol 2021; 70:908-921. [PMID: 33410870 DOI: 10.1093/sysbio/syaa085] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022] Open
Abstract
Evidence from natural systems suggests that hybridization between animal species is more common than traditionally thought, but the overall contribution of introgression to standing genetic variation within species remains unclear for most animal systems. Here, we use targeted exon-capture to sequence thousands of nuclear loci and complete mitochondrial genomes from closely related chipmunk species in the Tamias quadrivittatus group that are distributed across the Great Basin and the central and southern Rocky Mountains of North America. This recent radiation includes six overlapping, ecologically distinct species (T. canipes, T. cinereicollis, T. dorsalis, T. quadrivittatus, T. rufus, and T. umbrinus) that show evidence for widespread introgression across species boundaries. Such evidence has historically been derived from a handful of markers, typically focused on mitochondrial loci, to describe patterns of introgression; consequently, the extent of introgression of nuclear genes is less well characterized. We conducted a series of phylogenomic and species-tree analyses to resolve the phylogeny of six species in this group. In addition, we performed several population genomic analyses to characterize nuclear genomes and infer coancestry among individuals. Furthermore, we used emerging quartets-based approaches to simultaneously infer the species tree (SVDquartets) and identify introgression (HyDe). We found that, in spite of rampant introgression of mitochondrial genomes between some species pairs (and sometimes involving up to three species), there appears to be little to no evidence for nuclear introgression. These findings mirror other genomic results where complete mitochondrial capture has occurred between chipmunk species in the absence of appreciable nuclear gene flow. The underlying causes of recurrent massive cytonuclear discordance remain unresolved in this group but mitochondrial DNA appears highly misleading of population histories as a whole. Collectively, it appears that chipmunk species boundaries are largely impermeable to nuclear gene flow and that hybridization, while pervasive with respect to mtDNA, has likely played a relatively minor role in the evolutionary history of this group.
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Affiliation(s)
- Brice A J Sarver
- Department of Biological Sciences, University of Idaho, Moscow, Idaho.,Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow Idaho
| | | | - David Sneddon
- Department of Biological Sciences, University of Idaho, Moscow, Idaho
| | - Samuel S Hunter
- Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow Idaho.,UC-Davis Genome Center, Davis, California
| | | | | | - John R Demboski
- Department of Zoology, Denver Museum of Nature & Sciences, Denver, Colorado
| | - Jeffrey M Good
- Division of Biological Sciences, University of Montana, Missoula, Montana.,Wildlife Biology Program, University of Montana, Missoula, Montana
| | - Jack Sullivan
- Department of Biological Sciences, University of Idaho, Moscow, Idaho.,Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow Idaho
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Langton‐Myers SS, Holwell GI, Buckley TR. Weak premating isolation betweenClitarchusstick insect species despite divergent male and female genital morphology. J Evol Biol 2019; 32:398-411. [DOI: 10.1111/jeb.13424] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/30/2019] [Accepted: 02/01/2019] [Indexed: 01/06/2023]
Affiliation(s)
- Shelley S. Langton‐Myers
- Manaaki Whenua – Landcare Research Auckland New Zealand
- School of Biological SciencesThe University of Auckland Auckland New Zealand
- EcoQuest Education Foundation ‐ Te Rarangahau Taiao Whakatiwai New Zealand
| | - Gregory I. Holwell
- School of Biological SciencesThe University of Auckland Auckland New Zealand
| | - Thomas R. Buckley
- Manaaki Whenua – Landcare Research Auckland New Zealand
- School of Biological SciencesThe University of Auckland Auckland New Zealand
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Sarver BAJ, Demboski JR, Good JM, Forshee N, Hunter SS, Sullivan J. Comparative Phylogenomic Assessment of Mitochondrial Introgression among Several Species of Chipmunks (Tamias). Genome Biol Evol 2018; 9:7-19. [PMID: 28172670 PMCID: PMC5381575 DOI: 10.1093/gbe/evw254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2016] [Indexed: 11/16/2022] Open
Abstract
Many species are not completely reproductively isolated, resulting in hybridization and genetic introgression. Organellar genomes, such as those derived from mitochondria (mtDNA) and chloroplasts, introgress frequently in natural systems; however, the forces shaping patterns of introgression are not always clear. Here, we investigate extensive mtDNA introgression in western chipmunks, focusing on species in the Tamias quadrivittatus group from the central and southern Rocky Mountains. Specifically, we investigate the role of selection in driving patterns of introgression. We sequenced 51 mtDNA genomes from six species and combine these sequences with other published genomic data to yield annotated mitochondrial reference genomes for nine species of chipmunks. Genomic characterization was performed using a series of molecular evolutionary and phylogenetic analyses to test protein-coding genes for positive selection. We fit a series of maximum likelihood models using a model-averaging approach, assessed deviations from neutral expectations, and performed additional tests to search for codons under the influence of selection. We found no evidence for positive selection among these genomes, suggesting that selection has not been the driving force of introgression in these species. Thus, extensive mtDNA introgression among several species of chipmunks likely reflects genetic drift of introgressed alleles in historically fluctuating populations.
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Affiliation(s)
- Brice A J Sarver
- Department of Zoology, Denver Museum of Nature & Science, Denver, CO.,Department of Biological Sciences, University of Idaho, Moscow, ID.,Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID
| | - John R Demboski
- Department of Zoology, Denver Museum of Nature & Science, Denver, CO
| | - Jeffrey M Good
- Division of Biological Sciences, University of Montana, Missoula, MT
| | - Nicholas Forshee
- Department of Biological Sciences, University of Idaho, Moscow, ID
| | - Samuel S Hunter
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID
| | - Jack Sullivan
- Department of Biological Sciences, University of Idaho, Moscow, ID.,Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID
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Patterson BD, Norris RW. Towards a uniform nomenclature for ground squirrels: the status of the Holarctic chipmunks. MAMMALIA 2016. [DOI: 10.1515/mammalia-2015-0004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe chipmunks are a Holarctic group of ground squirrels currently allocated to the genus
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Sullivan J, Demboski JR, Bell KC, Hird S, Sarver B, Reid N, Good JM. Divergence with gene flow within the recent chipmunk radiation (Tamias). Heredity (Edinb) 2014; 113:185-94. [PMID: 24781803 DOI: 10.1038/hdy.2014.27] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/08/2014] [Accepted: 01/17/2014] [Indexed: 12/25/2022] Open
Abstract
Increasing data have supported the importance of divergence with gene flow (DGF) in the generation of biological diversity. In such cases, lineage divergence occurs on a shorter timescale than does the completion of reproductive isolation. Although it is critical to explore the mechanisms driving divergence and preventing homogenization by hybridization, it is equally important to document cases of DGF in nature. Here we synthesize data that have accumulated over the last dozen or so years on DGF in the chipmunk (Tamias) radiation with new data that quantify very high rates of mitochondrial DNA (mtDNA) introgression among para- and sympatric species in the T. quadrivittatus group in the central and southern Rocky Mountains. These new data (188 cytochrome b sequences) bring the total number of sequences up to 1871; roughly 16% (298) of the chipmunks we have sequenced exhibit introgressed mtDNA. This includes ongoing introgression between subspecies and between both closely related and distantly related taxa. In addition, we have identified several taxa that are apparently fixed for ancient introgressions and in which there is no evidence of ongoing introgression. A recurrent observation is that these introgressions occur between ecologically and morphologically diverged, sometimes non-sister taxa that engage in well-documented niche partitioning. Thus, the chipmunk radiation in western North America represents an excellent mammalian example of speciation in the face of recurrent gene flow among lineages and where biogeography, habitat differentiation and mating systems suggest important roles for both ecological and sexual selection.
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Affiliation(s)
- J Sullivan
- 1] Department of Biological Sciences and Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, USA [2] BEACON Center for the Study of Evolution in Action
| | - J R Demboski
- Department of Zoology, Denver Museum of Nature & Science, Denver, CO, USA
| | - K C Bell
- Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM, USA
| | - S Hird
- Department of Biological Sciences and Museum of Natural Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - B Sarver
- 1] Department of Biological Sciences and Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, USA [2] BEACON Center for the Study of Evolution in Action
| | - N Reid
- Department of Biological Sciences and Museum of Natural Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - J M Good
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
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Rapson SA, Goldizen AW, Seddon JM. Species boundaries and possible hybridization between the black mongoose (Galerella nigrata) and the slender mongoose (Galerella sanguinea). Mol Phylogenet Evol 2012; 65:831-9. [PMID: 22940151 DOI: 10.1016/j.ympev.2012.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 05/28/2012] [Accepted: 08/09/2012] [Indexed: 11/29/2022]
Abstract
Major climatic oscillations since the mid-Miocene climatic optimum are known to have played a key role in promoting speciation events. In this study we use molecular data to elucidate the evolutionary history of Galerella nigrata and link its divergence to known major climatic events. A total of 51 samples from G. nigrata and 17 from Galerella sanguinea were used to provide the first molecular evidence that G. nigrata may be a species in its own right. Both mitochondrial cytochrome b and the nuclear ß-fibrinogen intron seven sequences of G. nigrata form distinct monophyletic clades, separate from its sister species G. sanguinea. We estimate the divergence of these two species to have occurred 3.85-4.27 million years ago, coinciding with a period of the Plio-Pleistocene that was characterised by cooling global temperatures and strong aridity in southern Africa. However, evidence for potential hybridization between the two species was documented for ten individuals using phenotypic (pelage colouration) and/or molecular (nuclear and mtDNA sequences and microsatellite loci) data. There appeared to be a bias towards unidirectional hybridization with all potential hybrids showing mtDNA haplotypes from G. nigrata. We suggest that as the desert expanded across Namibia, G. sanguinea likely retreated with the savanna, leaving some mongooses stranded on the granite inselbergs of north-western Namibia. Subsequent adaptation of these mongooses to local conditions on granite inselbergs could have led to ecological speciation. Secondary contact zones would have been re-established with subsequent global warming events. It appears that the two species have not yet undergone complete reproductive isolation.
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Affiliation(s)
- Sara A Rapson
- The University of Queensland, School of Biological Sciences, St. Lucia Campus, Australia.
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Reid N, Demboski JR, Sullivan J. Phylogeny estimation of the radiation of western North American chipmunks (Tamias) in the face of introgression using reproductive protein genes. Syst Biol 2011; 61:44-62. [PMID: 21878471 DOI: 10.1093/sysbio/syr094] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The causes and consequences of rapid radiations are major unresolved issues in evolutionary biology. This is in part because phylogeny estimation is confounded by processes such as stochastic lineage sorting and hybridization. Because these processes are expected to be heterogeneous across the genome, comparison among marker classes may provide a means of disentangling these elements. Here we use introns from nuclear-encoded reproductive protein genes expected to be resistant to introgression to estimate the phylogeny of the western chipmunks (Tamias: subgenus: Neotamias), a rapid radiation that has experienced introgressive hybridization of mitochondrial DNA (mtDNA). We analyze the nuclear loci using coalescent-based species-tree estimation methods and concatenation to estimate a species tree and we use parametric bootstraps and coalescent simulations to differentiate between phylogenetic error, coalescent stochasticity and introgressive hybridization. Results indicate that the mtDNA gene tree reflects several introgression events that have occurred between taxa of varying levels of divergence and at different time points in the tree. T. panamintinus and T. speciosus appear to be fixed for ancient mitochondrial introgressions from T. minimus. A southern Rocky Mountains clade appears well sorted (i.e., species are largely monophyletic) at multiple nuclear loci, while five of six taxa are nonmonophyletic based on cytochrome b. Our simulations reject phylogenetic error and coalescent stochasticity as causes. The results represent an advance in our understanding of the processes at work during the radiation of Tamias and suggest that sampling reproductive-protein genes may be a viable strategy for phylogeny estimation of rapid radiations in which reproductive isolation is incomplete. However, a genome-scale survey that can statistically compare heterogeneity of genealogical process at many more loci will be necessary to test this conclusion.
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Affiliation(s)
- Noah Reid
- Department of Biological Sciences, Room 105, Louisiana State University, Baton Rouge, LA 70803, USA.
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