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Muñoz‐Valencia V, Vélez‐Martínez GA, Montoya‐Lerma J, Díaz F. Role of the Andean uplift as an asymmetrical barrier to gene flow in the neotropical leaf‐cutting ant
Atta cephalotes. Biotropica 2021. [DOI: 10.1111/btp.13050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Vanessa Muñoz‐Valencia
- Grupo de Ecología de Agroecosistemas y Hábitats Naturales Universidad del Valle Cali, Valle del Cauca Colombia
| | | | - James Montoya‐Lerma
- Grupo de Ecología de Agroecosistemas y Hábitats Naturales Universidad del Valle Cali, Valle del Cauca Colombia
| | - Fernando Díaz
- Biology Department Colgate University Hamilton New York USA
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2
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Hernández-Hernández T, Miller EC, Román-Palacios C, Wiens JJ. Speciation across the Tree of Life. Biol Rev Camb Philos Soc 2021; 96:1205-1242. [PMID: 33768723 DOI: 10.1111/brv.12698] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 01/04/2023]
Abstract
Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.
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Affiliation(s)
- Tania Hernández-Hernández
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A.,Catedrática CONACYT asignada a LANGEBIO-UGA Cinvestav, Libramiento Norte Carretera León Km 9.6, 36821, Irapuato, Guanajuato, Mexico
| | - Elizabeth C Miller
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - Cristian Román-Palacios
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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Fletcher NK, Acevedo P, Herman JS, Paupério J, Alves PC, Searle JB. Glacial cycles drive rapid divergence of cryptic field vole species. Ecol Evol 2019; 9:14101-14113. [PMID: 31938506 PMCID: PMC6953675 DOI: 10.1002/ece3.5846] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 11/07/2022] Open
Abstract
Understanding the factors that contribute to the generation of reproductively isolated forms is a fundamental goal of evolutionary biology. Cryptic species are an especially interesting challenge to study in this context since they lack obvious morphological differentiation that provides clues to adaptive divergence that may drive reproductive isolation. Geographical isolation in refugial areas during glacial cycling is known to be important for generating genetically divergent populations, but its role in the origination of new species is still not fully understood and likely to be situation dependent. We combine analysis of 35,434 single-nucleotide polymorphisms (SNPs) with environmental niche modeling (ENM) to investigate genomic and ecological divergence in three cryptic species formerly classified as the field vole (Microtus agrestis). The SNPs demonstrate high genomic divergence (pairwise F ST values of 0.45-0.72) and little evidence of gene flow among the three field vole cryptic species, and we argue that genetic drift may have been a particularly important mechanism for divergence in the group. The ENM reveals three areas as potential glacial refugia for the cryptic species and differing climatic niches, although with spatial overlap between species pairs. This evidence underscores the role that glacial cycling has in promoting genetic differentiation and reproductive isolation by subdivision into disjunct distributions at glacial maxima in areas relatively close to ice sheets. Future investigation of the intrinsic barriers to gene flow between the field vole cryptic species is required to fully assess the mechanisms that contribute to reproductive isolation. In addition, the Portuguese field vole (M. rozianus) shows a high inbreeding coefficient and a restricted climatic niche, and warrants investigation into its conservation status.
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Affiliation(s)
| | - Pelayo Acevedo
- Instituto de Investigación en Recursos Cinegéticos, IREC (UCLM‐CSIC‐JCCM)Ciudad RealSpain
| | - Jeremy S. Herman
- Department of Natural SciencesNational Museums ScotlandEdinburghUK
| | - Joana Paupério
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos GenéticosUniversidade do Porto, Campus de VairãoVairãoPortugal
| | - Paulo C. Alves
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos GenéticosUniversidade do Porto, Campus de VairãoVairãoPortugal
- Departamento de BiologiaFaculdade de CiênciasUniversidade do PortoPortoPortugal
| | - Jeremy B. Searle
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNYUSA
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos GenéticosUniversidade do Porto, Campus de VairãoVairãoPortugal
- Departamento de BiologiaFaculdade de CiênciasUniversidade do PortoPortoPortugal
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4
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Fernández CJ, González-Ittig RE, García BA. Genetic structure of the Chagas disease vector Triatoma infestans (Hemiptera: Reduviidae) based on nuclear and mitochondrial DNA sequences. Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractIn the present study, we analysed the genetic structure of Triatoma infestans populations with a phylogeographical approach using sequences of the mitochondrial NADH dehydrogenase subunit 5 (ND5) and the nuclear elongation factor-1 alpha (EF-1α) genes of bugs obtained from Argentina and Bolivia. Spatially circumscribed haplogroups were distinguished from the ND5 gene sequences, one distributed exclusively to the south of the studied area and, in agreement with the results from the EF-1α gene, one haplogroup limited to Bolivia and another to Morajú located in the Chaco region of Argentina. In both the ND5 and EF-1α networks, the most widespread haplogroup or allele group showed a star-like topology, which is compatible with a recent demographic expansion. The asymmetric historical gene flow detected from a population of the Chaco region towards Bolivia and the spatiotemporal phylogeographical reconstruction of lineage dispersal would support the hypothesis that postulates the Chaco biogeographical region as the area of origin for the species. However, additional studies with a broader sampling in the Andean region are needed to define with certainty whether the origin of T. infestans is Chacoan or Andean.
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Affiliation(s)
- Cintia J Fernández
- Instituto de Investigaciones en Ciencias de la Salud (INICSA), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba (CONICET-UNC), Córdoba, Argentina
- Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Raúl E González-Ittig
- Instituto de Diversidad y Ecología Animal (IDEA), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba (CONICET-UNC), Córdoba, Argentina
- Cátedra de Genética de Poblaciones y Evolución, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Beatriz A García
- Instituto de Investigaciones en Ciencias de la Salud (INICSA), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Córdoba (CONICET-UNC), Córdoba, Argentina
- Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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Gray DA, Hormozi S, Libby FR, Cohen RW. Induced expression of a vestigial sexual signal. Biol Lett 2018; 14:20180095. [PMID: 29769298 PMCID: PMC6012708 DOI: 10.1098/rsbl.2018.0095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/23/2018] [Indexed: 11/12/2022] Open
Abstract
Vestigial morphological traits are common and well known in a variety of taxa. Identification of vestigial genes has illustrated the potential for evolutionary reversals and the re-expression of atavistic traits. Here we induce expression of a behavioural sexual signal, male calling song, in a cricket species, Gryllus ovisopis, which lacks a functional calling song. We successfully used acetylcholine injections in the frontal space of the head of male crickets to activate cerebral command neurons for cricket calling, and we recorded calling songs with a temporal chirp pattern similar to that of G. ovisopis' close evolutionary relatives, G. firmus and G. pennsylvanicus, implying that the neural pattern generators that underlie cricket calling behaviour persist in a vestigial state in G. ovisopis To our knowledge, this is the first demonstration of the induced expression of a vestigial behaviour in any organism. The retention of latent neural capacity to express sexual behaviours could have important implications for rapid evolution, trait re-emergence and reproductive isolation.
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Affiliation(s)
- David A Gray
- Department of Biology, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA
| | - Scherezade Hormozi
- Department of Biology, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA
| | - Fritz R Libby
- Department of Biology, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA
| | - Randy W Cohen
- Department of Biology, California State University, Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA
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Delahaie B, Cornuault J, Masson C, Bertrand JAM, Bourgeois YXC, Milá B, Thébaud C. Narrow hybrid zones in spite of very low population differentiation in neutral markers in an island bird species complex. J Evol Biol 2017; 30:2132-2145. [DOI: 10.1111/jeb.13177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/26/2017] [Accepted: 09/07/2017] [Indexed: 02/06/2023]
Affiliation(s)
- B. Delahaie
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
- Centre d'Ecologie Fonctionnelle et Evolutive; CNRS-UMR5175 CEFE; Montpellier France
| | - J. Cornuault
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - C. Masson
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - J. A. M. Bertrand
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - Y. X. C. Bourgeois
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - B. Milá
- National Museum of Natural Sciences; Spanish National Research Council (CSIC); Madrid Spain
| | - C. Thébaud
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
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7
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Multivariate Phenotypic Evolution: Divergent Acoustic Signals and Sexual Selection in Gryllus Field Crickets. Evol Biol 2016. [DOI: 10.1007/s11692-016-9388-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Noh S, Marshall JL. Sorted gene genealogies and species-specific nonsynonymous substitutions point to putative postmating prezygotic isolation genes in Allonemobius crickets. PeerJ 2016; 4:e1678. [PMID: 26893965 PMCID: PMC4756749 DOI: 10.7717/peerj.1678] [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: 09/11/2015] [Accepted: 01/14/2016] [Indexed: 12/19/2022] Open
Abstract
In the Allonemobius socius complex of crickets, reproductive isolation is primarily accomplished via postmating prezygotic barriers. We tested seven protein-coding genes expressed in the male ejaculate for patterns of evolution consistent with a putative role as postmating prezygotic isolation genes. Our recently diverged species generally lacked sequence variation. As a result, ω-based tests were only mildly successful. Some of our genes showed evidence of elevated ω values on the internal branches of gene trees. In a couple of genes, these internal branches coincided with both species branching events of the species tree, between A. fasciatus and the other two species, and between A. socius and A. sp. nov. Tex. In comparison, more successful approaches were those that took advantage of the varying degrees of lineage sorting and allele sharing among our young species. These approaches were particularly powerful within the contact zone. Among the genes we tested we found genes with genealogies that indicated relatively advanced degrees of lineage sorting across both allopatric and contact zone alleles. Within a contact zone between two members of the species complex, only a subset of genes maintained allelic segregation despite evidence of ongoing gene flow in other genes. The overlap in these analyses was arginine kinase (AK) and apolipoprotein A-1 binding protein (APBP). These genes represent two of the first examples of sperm maturation, capacitation, and motility proteins with fixed non-synonymous substitutions between species-specific alleles that may lead to postmating prezygotic isolation. Both genes express ejaculate proteins transferred to females during copulation and were previously identified through comparative proteomics. We discuss the potential function of these genes in the context of the specific postmating prezygotic isolation phenotype among our species, namely conspecific sperm precedence and the superior ability of conspecific males to induce oviposition in females.
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Affiliation(s)
- Suegene Noh
- Department of Biology, Washington University in St. Louis , St. Louis, MO , United States
| | - Jeremy L Marshall
- Department of Entomology, Kansas State University , Manhattan, KS , United States
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9
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Gray DA, Gutierrez NJ, Chen TL, Gonzalez C, Weissman DB, Cole JA. Species divergence in field crickets: genetics, song, ecomorphology, and pre- and postzygotic isolation. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David A. Gray
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Nicholas J. Gutierrez
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Tom L. Chen
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Christopher Gonzalez
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - David B. Weissman
- Department of Entomology; California Academy of Sciences; San Francisco CA 94118 USA
| | - Jeffrey A. Cole
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
- Department of Biology; Pasadena City College; Pasadena CA 91106 USA
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Maroja LS, Larson EL, Bogdanowicz SM, Harrison RG. Genes with Restricted Introgression in a Field Cricket (Gryllus firmus/Gryllus pennsylvanicus) Hybrid Zone Are Concentrated on the X Chromosome and a Single Autosome. G3 (BETHESDA, MD.) 2015; 5:2219-27. [PMID: 26311650 PMCID: PMC4632042 DOI: 10.1534/g3.115.021246] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/17/2015] [Indexed: 01/06/2023]
Abstract
Characterizing the extent of genomic differentiation between recently diverged lineages provides an important context for understanding the early stages of speciation. When such lineages form discrete hybrid zones, patterns of differential introgression allow direct estimates of which genome regions are likely involved in speciation and local adaptation. Here we use a backcross experimental design to construct a genetic linkage map for the field crickets Gryllus firmus and Gryllus pennsylvanicus, which interact in a well-characterized hybrid zone in eastern North America. We demonstrate that loci with major allele frequency differences between allopatric populations are not randomly distributed across the genome. Instead, most are either X-linked or map to a few small autosomal regions. Furthermore, the subset of those highly differentiated markers that exhibit restricted introgression across the cricket hybrid zone are also concentrated on the X chromosome (39 of 50 loci) and in a single 7-cM region of one autosome. Although the accumulation on the sex chromosome of genes responsible for postzygotic barriers is a well-known phenomenon, less attention has been given to the genomic distribution of genes responsible for prezygotic barriers. We discuss the implications of our results for speciation, both in the context of the role of sex chromosomes and also with respect to the likely causes of heterogeneous genomic divergence. Although we do not yet have direct evidence for the accumulation of ecological, behavioral, or fertilization prezygotic barrier genes on the X chromosome, faster-X evolution could make these barriers more likely to be X-linked.
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Affiliation(s)
- Luana S Maroja
- Department of Biology, Williams College, Williamstown, Massachusetts 01267
| | - Erica L Larson
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Steven M Bogdanowicz
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853
| | - Richard G Harrison
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853
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11
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Larson EL, White TA, Ross CL, Harrison RG. Gene flow and the maintenance of species boundaries. Mol Ecol 2013; 23:1668-78. [DOI: 10.1111/mec.12601] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Erica L. Larson
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca NY 14853 USA
- Division of Biological Sciences; University of Montana; Missoula MT 59812 USA
| | - Thomas A. White
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca NY 14853 USA
- CMPG Lab; Institute of Ecology and Evolution; University of Bern; Baltzerstrasse 6 3012 Bern Switzerland
| | - Charles L. Ross
- School of Natural Science; Hampshire College; Amherst MA 01002 USA
| | - Richard G. Harrison
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca NY 14853 USA
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12
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Crawford JE, Nielsen R. Detecting adaptive trait loci in nonmodel systems: divergence or admixture mapping? Mol Ecol 2013; 22:6131-48. [DOI: 10.1111/mec.12562] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/09/2013] [Accepted: 10/11/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Jacob E. Crawford
- Department of Integrative Biology; University of California; Berkeley 4134 Valley Life Sciences Building Berkeley CA 94720-3140 USA
| | - Rasmus Nielsen
- Department of Integrative Biology; University of California; Berkeley 4098 Valley Life Sciences Building Berkeley CA 94720-3140 USA
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Cryptic patterns of diversification of a widespread Amazonian Woodcreeper species complex (Aves: Dendrocolaptidae) inferred from multilocus phylogenetic analysis: Implications for historical biogeography and taxonomy. Mol Phylogenet Evol 2013; 68:410-24. [DOI: 10.1016/j.ympev.2013.04.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 01/20/2023]
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Larson EL, Andrés JA, Bogdanowicz SM, Harrison RG. Differential introgression in a mosaic hybrid zone reveals candidate barrier genes. Evolution 2013; 67:3653-61. [PMID: 24299416 DOI: 10.1111/evo.12205] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 06/19/2013] [Indexed: 02/06/2023]
Abstract
Hybrid zones act as genomic sieves. Although globally advantageous alleles will spread throughout the zone and neutral alleles can be freely exchanged between species, introgression will be restricted for genes that contribute to reproductive barriers or local adaptation. Seminal fluid proteins (SFPs) are known to contribute to reproductive barriers in insects and have been proposed as candidate barrier genes in the hybridizing field crickets Gryllus pennsylvanicus and Gryllus firmus. Here, we have used 125 single nucleotide polymorphisms to characterize patterns of differential introgression and to identify genes that may contribute to prezygotic barriers between these species. Using a transcriptome scan of the male cricket accessory gland (the site of SFP synthesis), we identified genes with major allele frequency differences between the species. We then compared patterns of introgression for genes encoding SFPs with patterns for genes expressed in the same tissue that do not encode SFPs. We find no evidence that SFPs have reduced gene exchange across the cricket hybrid zone. However, a number of genes exhibit dramatically reduced introgression, and many of these genes encode proteins with functional roles consistent with known barriers.
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Affiliation(s)
- Erica L Larson
- Division of Biological Sciences, University of Montana, Missoula, Montana; Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York.
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Zou XH, Yang Z, Doyle JJ, Ge S. Multilocus estimation of divergence times and ancestral effective population sizes of Oryza species and implications for the rapid diversification of the genus. THE NEW PHYTOLOGIST 2013; 198:1155-1164. [PMID: 23574344 DOI: 10.1111/nph.12230] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/08/2013] [Indexed: 06/02/2023]
Abstract
· Despite substantial investigations into Oryza phylogeny and evolution, reliable estimates of the divergence times and ancestral effective population sizes of major lineages in Oryza are challenging. · We sampled sequences of 106 single-copy nuclear genes from all six diploid genomes of Oryza to investigate the divergence times through extensive relaxed molecular clock analyses and estimated the ancestral effective population sizes using maximum likelihood and Bayesian methods. · We estimated that Oryza originated in the middle Miocene (c. 13-15 million years ago; Ma) and obtained an explicit time frame for two rapid diversifications in this genus. The first diversification involving the extant F-/G-genomes and possibly the extinct H-/J-/K-genomes occurred in the middle Miocene immediately after (within < 1 Myr) the origin of Oryza. The second giving rise to the A-/B-/C-genomes happened c. 5-6 Ma. We found that ancestral effective population sizes were much larger than those of extant species in Oryza. · We suggest that the climate fluctuations during the period from the middle Miocene to Pliocene may have contributed to the two rapid diversifications of Oryza species. Such information helps better understand the evolutionary history of Oryza and provides further insights into the pattern and mechanism of diversification in plants in general.
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Affiliation(s)
- Xin-Hui Zou
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Ziheng Yang
- Center for Computational and Evolutionary Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Jeff J Doyle
- Department of Plant Biology, Cornell University, 412 Mann Library Building, Ithaca, NY, 14853, USA
| | - Song Ge
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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Patterns of transcriptome divergence in the male accessory gland of two closely related species of field crickets. Genetics 2012; 193:501-13. [PMID: 23172857 DOI: 10.1534/genetics.112.142299] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One of the central questions in evolutionary genetics is how much of the genome is involved in the early stages of divergence between populations, causing them to be reproductively isolated. In this article, we investigate genomic differentiation in a pair of closely related field crickets (Gryllus firmus and G. pennsylvanicus). These two species are the result of allopatric divergence and now interact along an extensive hybrid zone in eastern North America. Genes encoding seminal fluid proteins (SFPs) are often divergent between species, and it has been hypothesized that these proteins may play a key role in the origin and maintenance of reproductive isolation between diverging lineages. Hence, we chose to scan the accessory gland transcriptome to enable direct comparisons of differentiation for genes known to encode SFPs with differentiation in a much larger set of genes expressed in the same tissue. We have characterized differences in allele frequency between two populations for >6000 SNPs and >26,000 contigs. About 10% of all SNPs showed nearly fixed differences between the two species. Genes encoding SFPs did not have significantly elevated numbers of fixed SNPs per contig, nor did they seem to show larger differences than expected in their average allele frequencies. The distribution of allele frequency differences across the transcriptome is distinctly bimodal, but the relatively high proportion of fixed SNPs does not necessarily imply "ancient" divergence between these two lineages. Further studies of linkage disequilibrium and introgression across the hybrid zone are needed to direct our attention to those genome regions that are important for reproductive isolation.
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Walker DM, Castlebury LA, Rossman AY, Mejía LC, White JF. Phylogeny and taxonomy of Ophiognomonia (Gnomoniaceae, Diaporthales), including twenty-five new species in this highly diverse genus. FUNGAL DIVERS 2012. [DOI: 10.1007/s13225-012-0200-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Larson EL, Hume GL, Andrés JA, Harrison RG. Post-mating prezygotic barriers to gene exchange between hybridizing field crickets. J Evol Biol 2011; 25:174-86. [PMID: 22092687 DOI: 10.1111/j.1420-9101.2011.02415.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Studies of sexual selection in speciation have traditionally focused on mate preference, with less attention given to traits that act between copulation and fertilization. However, recent work suggests that post-mating prezygotic barriers may play an important role in speciation. Here, we evaluate the role of such barriers in the field crickets, Gryllus firmus and Gryllus pennsylvanicus. Gryllus pennsylvanicus females mated with G. firmus males produce viable, fertile offspring, but when housed with both species produce offspring sired primarily by conspecifics. We evaluate patterns of sperm utilization in doubly mated G. pennsylvanicus females and find no evidence for conspecific sperm precedence. The reciprocal cross (G. firmus female × G. pennsylvanicus male) produces no progeny. Absence of progeny reflects a barrier to fertilization rather than reduced sperm transfer, storage or motility. We propose a classification scheme for mechanisms underlying post-mating prezygotic barriers similar to that used for premating barriers.
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Affiliation(s)
- Erica L Larson
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.
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SHREVE SCOTTM, MOCKFORD EDWARDL, JOHNSON KEVINP. Elevated genetic diversity of mitochondrial genes in asexual populations of Bark Lice (‘Psocoptera’: Echmepteryx hageni). Mol Ecol 2011; 20:4433-51. [DOI: 10.1111/j.1365-294x.2011.05298.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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20
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Sequeira F, Sodré D, Ferrand N, Bernardi JAR, Sampaio I, Schneider H, Vallinoto M. Hybridization and massive mtDNA unidirectional introgression between the closely related Neotropical toads Rhinella marina and R. schneideri inferred from mtDNA and nuclear markers. BMC Evol Biol 2011; 11:264. [PMID: 21939538 PMCID: PMC3192708 DOI: 10.1186/1471-2148-11-264] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 09/22/2011] [Indexed: 11/18/2022] Open
Abstract
Background The classical perspective that interspecific hybridization in animals is rare has been changing due to a growing list of empirical examples showing the occurrence of gene flow between closely related species. Using sequence data from cyt b mitochondrial gene and three intron nuclear genes (RPL9, c-myc, and RPL3) we investigated patterns of nucleotide polymorphism and divergence between two closely related toad species R. marina and R. schneideri. By comparing levels of differentiation at nuclear and mtDNA levels we were able to describe patterns of introgression and infer the history of hybridization between these species. Results All nuclear loci are essentially concordant in revealing two well differentiated groups of haplotypes, corresponding to the morphologically-defined species R. marina and R. schneideri. Mitochondrial DNA analysis also revealed two well-differentiated groups of haplotypes but, in stark contrast with the nuclear genealogies, all R. schneideri sequences are clustered with sequences of R. marina from the right Amazon bank (RAB), while R. marina sequences from the left Amazon bank (LAB) are monophyletic. An Isolation-with-Migration (IM) analysis using nuclear data showed that R. marina and R. schneideri diverged at ≈ 1.69 Myr (early Pleistocene), while R. marina populations from LAB and RAB diverged at ≈ 0.33 Myr (middle Pleistocene). This time of divergence is not consistent with the split between LAB and RAB populations obtained with mtDNA data (≈ 1.59 Myr), which is notably similar to the estimate obtained with nuclear genes between R. marina and R. schneideri. Coalescent simulations of mtDNA phylogeny under the speciation history inferred from nuclear genes rejected the hypothesis of incomplete lineage sorting to explain the conflicting signal between mtDNA and nuclear-based phylogenies. Conclusions The cytonuclear discordance seems to reflect the occurrence of interspecific hybridization between these two closely related toad species. Overall, our results suggest a phenomenon of extensive mtDNA unidirectional introgression from the previously occurring R. schneideri into the invading R. marina. We hypothesize that climatic-induced range shifts during the Pleistocene/Holocene may have played an important role in the observed patterns of introgression.
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Wachowiak W, Palmé AE, Savolainen O. Speciation history of three closely related pines Pinus mugo (T.), P. uliginosa (N.) and P. sylvestris (L.). Mol Ecol 2011; 20:1729-43. [PMID: 21375633 DOI: 10.1111/j.1365-294x.2011.05037.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Nucleotide polymorphisms at genomic regions including 17 nuclear loci, two chloroplast and one mitochondrial DNA fragments were used to study the speciation history of three pine species: dwarf mountain pine (Pinus mugo), peat-bog pine (P. uliginosa) and Scots pine (P. sylvestris). We set out to investigate three specific speciation scenarios: (I) P. uliginosa is a homoploid hybrid between the other two, (II) the species have evolved without gene flow after divergence and (III) there has been substantial gene flow between the species since their divergence. Overall, the genetic data suggest that P. mugo and P. uliginosa share the same gene pool (average net divergence of 0.0001) and that the phenotypic differences (e.g. growth form) are most likely due to very limited areas of the genome. P. mugo and P. uliginosa are more diverged from P. sylvestris than from each other (average net divergence of 0.0027 and 0.0026, respectively). The nucleotide patterns can best be explained by the divergence with migration speciation scenario, although the hybrid speciation scenario with small genomic contribution from P. sylvestris cannot be completely ruled out. We suggest that the large amount of shared polymorphisms between the pine taxa and the lack of monophyly at all loci studied between P. sylvestris and P. mugo-P. uliginosa can largely be explained by relatively recent speciation history and large effective population sizes but also by interspecific gene flow. These closely related pine taxa form an excellent system for searching for loci involved in adaptive variation as they are differentiated in phenotype and ecology but have very similar genetic background.
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Affiliation(s)
- Witold Wachowiak
- Department of Biology, University of Oulu, 90014, Oulu, Finland.
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22
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Hewitt GM. Quaternary phylogeography: the roots of hybrid zones. Genetica 2011; 139:617-38. [DOI: 10.1007/s10709-011-9547-3] [Citation(s) in RCA: 244] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 01/03/2011] [Indexed: 10/18/2022]
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Brunes TO, Sequeira F, Haddad CF, Alexandrino J. Gene and species trees of a Neotropical group of treefrogs: Genetic diversification in the Brazilian Atlantic Forest and the origin of a polyploid species. Mol Phylogenet Evol 2010; 57:1120-33. [DOI: 10.1016/j.ympev.2010.08.026] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 08/08/2010] [Accepted: 08/24/2010] [Indexed: 11/24/2022]
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Zheng XM, Ge S. Ecological divergence in the presence of gene flow in two closely related Oryza species (Oryza rufipogon and O. nivara). Mol Ecol 2010; 19:2439-54. [PMID: 20653085 DOI: 10.1111/j.1365-294x.2010.04674.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Ecological divergence plays a prominent role in the process of speciation, but how divergence occurs in the face of gene flow is still less clear, and remains controversial among evolutionists. Here we investigated the nucleotide diversity, divergence and gene flow between Oryza nivara and O. rufipogon using sequences of seven chloroplast and nuclear loci. By analysing samples from 26 wild populations across the geographic ranges of the two species, we showed that both species were highly structured and O. rufipogon maintained a higher level of species-wide diversity than O. nivara. Notably, phylogenetic, amova and FST analyses were unable to detect significant nucleotide differentiation between the two species. We estimated that the two species began to diverge at c. 0.16 million years ago. Our coalescent-based simulations strongly rejected the simple isolation model of zero migration between species, but rather provided unambiguous evidence of bidirectional gene flow between species, particularly from O. rufipogon to O. nivara. Our simulations also indicated that gene flow was recurrent during the divergence process rather than arising from secondary contact after allopatric divergence. In conjunction with different morphological and life-history traits and habitat preference in the two species, this study supports the hypothesis that these Oryza species are better treated as ecotypes that diverged quite recently and are still under the process of divergence. Importantly, we demonstrate the ecological divergence between O. rufipogon and O. nivara in the presence of significant gene flow, implying that natural selection plays a primary role in driving the divergence of the two Oryza species.
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Affiliation(s)
- Xiao-Ming Zheng
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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25
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Marshall JL, Huestis DL, Garcia C, Hiromasa Y, Wheeler S, Noh S, Tomich JM, Howard DJ. Comparative Proteomics Uncovers the Signature of Natural Selection Acting on the Ejaculate Proteomes of Two Cricket Species Isolated by Postmating, Prezygotic Phenotypes. Mol Biol Evol 2010; 28:423-35. [DOI: 10.1093/molbev/msq230] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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PAYSEUR BRETA. Using differential introgression in hybrid zones to identify genomic regions involved in speciation. Mol Ecol Resour 2010; 10:806-20. [DOI: 10.1111/j.1755-0998.2010.02883.x] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Plouviez S, Le Guen D, Lecompte O, Lallier FH, Jollivet D. Determining gene flow and the influence of selection across the equatorial barrier of the East Pacific Rise in the tube-dwelling polychaete Alvinella pompejana. BMC Evol Biol 2010; 10:220. [PMID: 20663123 PMCID: PMC2924869 DOI: 10.1186/1471-2148-10-220] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 07/22/2010] [Indexed: 11/20/2022] Open
Abstract
Background Comparative phylogeography recently performed on the mitochondrial cytochrome oxidase I (mtCOI) gene from seven deep-sea vent species suggested that the East Pacific Rise fauna has undergone a vicariant event with the emergence of a north/south physical barrier at the Equator 1-2 Mya. Within this specialised fauna, the tube-dwelling polychaete Alvinella pompejana showed reciprocal monophyly at mtCOI on each side of the Equator (9°50'N/7°25'S), suggesting potential, ongoing allopatric speciation. However, the development of a barrier to gene flow is a long and complex process. Secondary contact between previously isolated populations can occur when physical isolation has not persisted long enough to result in reproductive isolation between genetically divergent lineages, potentially leading to hybridisation and subsequent allelic introgression. The present study evaluates the strength of the equatorial barrier to gene flow and tests for potential secondary contact zones between A. pompejana populations by comparing the mtCOI gene with nuclear genes. Results Allozyme frequencies and the analysis of nucleotide polymorphisms at three nuclear loci confirmed the north/south genetic differentiation of Alvinella pompejana populations along the East Pacific Rise. Migration was oriented north-to-south with a moderate allelic introgression between the two geographic groups over a narrow geographic range just south of the barrier. Multilocus analysis also indicated that southern populations have undergone demographic expansion as previously suggested by a multispecies approach. A strong shift in allozyme frequencies together with a high level of divergence between alleles and a low number of 'hybrid' individuals were observed between the northern and southern groups using the phosphoglucomutase gene. In contrast, the S-adenosylhomocysteine hydrolase gene exhibited reduced diversity and a lack of population differentiation possibly due to a selective sweep or hitch-hiking. Conclusions The equatorial barrier leading to the separation of East Pacific Rise vent fauna into two distinct geographic groups is still permeable to migration, with a probable north-to-south migration route for A. pompejana. This separation also coincides with demographic expansion in the southern East Pacific Rise. Our results suggest that allopatry resulting from ridge offsetting is a common mechanism of speciation for deep-sea hydrothermal vent organisms.
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Affiliation(s)
- Sophie Plouviez
- Université Pierre et Marie Curie-Paris 6, Laboratoire Adaptation et Diversité en Milieu Marin, Roscoff, France
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Thomé MTC, Zamudio KR, Giovanelli JG, Haddad CF, Baldissera FA, Alexandrino J. Phylogeography of endemic toads and post-Pliocene persistence of the Brazilian Atlantic Forest. Mol Phylogenet Evol 2010; 55:1018-31. [DOI: 10.1016/j.ympev.2010.02.003] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 01/30/2010] [Accepted: 02/02/2010] [Indexed: 11/25/2022]
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Liao PC, Kuo DC, Lin CC, Ho KC, Lin TP, Hwang SY. Historical spatial range expansion and a very recent bottleneck of Cinnamomum kanehirae Hay. (Lauraceae) in Taiwan inferred from nuclear genes. BMC Evol Biol 2010; 10:124. [PMID: 20433752 PMCID: PMC2880300 DOI: 10.1186/1471-2148-10-124] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 04/30/2010] [Indexed: 11/23/2022] Open
Abstract
Background Species in the varied geographic topology of Taiwan underwent obvious demographic changes during glacial periods. Cinnamomum kanehirae has been exploited for timber and to obtain medicinal fungi for the past 100 years. Understanding anthropogenic factors influencing the demography of this species after the last glacial maximum (LGM) is critically important for the conservation of this species. Results Populations of C. kanehirae were classified into four geographic regions: northwestern (NW), west-central (WC), southwestern (SW), and southeastern (SE). In total, 113 individuals from 19 localities were sampled, and variations in the chalcone synthase gene (Chs) intron and leafy (Lfy) intron-2 sequences of nuclear DNA were examined in order to assess phylogeographic patterns, the timescales of demographic and evolutionary events, and recent anthropogenic effects. In total, 210 Chs and 170 Lfy sequences, which respectively constituted 36 and 35 haplotypes, were used for the analyses. Estimates of the migration rate (M) through time revealed a pattern of frequent gene flow during previous and the present interglacials. The isolation-by-distance test showed that there generally was no significant correlation between genetic and geographic distances. The level of among-region genetic differentiation was significant when comparing eastern to western populations. However, no significant among-region genetic differentiation was found in comparisons among the four geographic regions. Moreover, essentially no genetic structuring was found for the three regions west of the CMR. A fit of spatial range expansion was found for pooled and regional samples according to the non-significant values of the sum of squared deviations. Using the Bayesian skyline plot (BSP) method, a recent bottleneck after the LGM expansion was detected in both regional and pooled samples. Conclusions Common haplotype distributions among geographic regions and the relatively shallow genetic structuring displayed are the result of historical gene flows. Southward dispersals in an earlier time frame from the NW region and in a later time frame from the SE region were inferred. The BSP analysis suggested a postglacial expansion event. Recent trends, however, refer to a bottleneck due to human interventions observed for both pooled and regional C. kanehirae samples.
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Affiliation(s)
- Pei-Chun Liao
- Department of Life Science, Pingtung University of Science and Technology, Pingtung, Taiwan
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30
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Garrick RC, Sunnucks P, Dyer RJ. Nuclear gene phylogeography using PHASE: dealing with unresolved genotypes, lost alleles, and systematic bias in parameter estimation. BMC Evol Biol 2010; 10:118. [PMID: 20429950 PMCID: PMC2880299 DOI: 10.1186/1471-2148-10-118] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 04/30/2010] [Indexed: 01/25/2023] Open
Abstract
Background A widely-used approach for screening nuclear DNA markers is to obtain sequence data and use bioinformatic algorithms to estimate which two alleles are present in heterozygous individuals. It is common practice to omit unresolved genotypes from downstream analyses, but the implications of this have not been investigated. We evaluated the haplotype reconstruction method implemented by PHASE in the context of phylogeographic applications. Empirical sequence datasets from five non-coding nuclear loci with gametic phase ascribed by molecular approaches were coupled with simulated datasets to investigate three key issues: (1) haplotype reconstruction error rates and the nature of inference errors, (2) dataset features and genotypic configurations that drive haplotype reconstruction uncertainty, and (3) impacts of omitting unresolved genotypes on levels of observed phylogenetic diversity and the accuracy of downstream phylogeographic analyses. Results We found that PHASE usually had very low false-positives (i.e., a low rate of confidently inferring haplotype pairs that were incorrect). The majority of genotypes that could not be resolved with high confidence included an allele occurring only once in a dataset, and genotypic configurations involving two low-frequency alleles were disproportionately represented in the pool of unresolved genotypes. The standard practice of omitting unresolved genotypes from downstream analyses can lead to considerable reductions in overall phylogenetic diversity that is skewed towards the loss of alleles with larger-than-average pairwise sequence divergences, and in turn, this causes systematic bias in estimates of important population genetic parameters. Conclusions A combination of experimental and computational approaches for resolving phase of segregating sites in phylogeographic applications is essential. We outline practical approaches to mitigating potential impacts of computational haplotype reconstruction on phylogeographic inferences. With targeted application of laboratory procedures that enable unambiguous phase determination via physical isolation of alleles from diploid PCR products, relatively little investment of time and effort is needed to overcome the observed biases.
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Affiliation(s)
- Ryan C Garrick
- Department of Biology, Virginia Commonwealth University, Richmond, 23284, USA.
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31
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Ferreira M, Ferguson JWH. Do Mediterranean crickets Gryllus bimaculatus De Geer (Orthoptera: Gryllidae) come from the Mediterranean? Largescale phylogeography and regional gene flow. BULLETIN OF ENTOMOLOGICAL RESEARCH 2010; 100:49-58. [PMID: 19323852 DOI: 10.1017/s0007485309006749] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We investigate the degree of between-population genetic differentiation in the Mediterranean field cricket Gryllus bimaculatus, as well as the possible causes of such differentiation. Using cytochrome b mtDNA sequences, we estimate genetic variation in G. bimaculatus from seven South African and two Mediterranean populations. Within-population genetic variation in Europe (two haplotypes, one unique to a single individual) suggest low effective population size and strong bottlenecks with associated founder effects, probably due to cold winter environments in Europe that limit reproduction to a short part of the summer. The likely cause for this is the daily maxima in winter temperatures that fall below the critical level of 16 degrees C (enabling normal calling and courtship behaviour) in Mediterranean Europe, whereas the equivalent temperatures in southern Africa are above this limit and enable reproduction over a large part of the year. European genetic variants were either shared with Africa or closely related to African haplotypes. For survival, European populations are probably dependent on immigration from other areas, including Africa. South African populations have low but measurable gene flow with Europe and show significant between-population genetic differentiation (30 haplotypes). Isolation-by-distance is not sufficient to explain the degree of between-population genetic differences observed, and a large degree of dispersal is also required in order to account for the observed patterns. Differences in morphology and calling behaviour among these populations are underlied by these genetic differences.
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Affiliation(s)
- M Ferreira
- Centre for Environmental Studies, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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Gladieux P, Caffier V, Devaux M, Le Cam B. Host-specific differentiation among populations of Venturia inaequalis causing scab on apple, pyracantha and loquat. Fungal Genet Biol 2010; 47:511-21. [PMID: 20060485 DOI: 10.1016/j.fgb.2009.12.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 12/14/2009] [Accepted: 12/16/2009] [Indexed: 10/20/2022]
Abstract
Patterns of multilocus DNA sequence variation within and between closely related taxa can provide insights into the history of divergence. Here, we report on DNA polymorphism and divergence at six nuclear loci in globally distributed samples of the ascomycete Venturia inaequalis, responsible for scab on apple, loquat, and pyracantha. Isolates from different hosts were differentiated but did not form diagnosable distinct phylogenetic species. Parameters of an Isolation-with-Migration model estimated from the data suggested that the large amount of variation shared among groups more likely resulted from recent splitting than from extensive genetic exchanges. Inferred levels of gene flow among groups were low and more concentrated toward recent times, and we identified two potentially recent one-off shifters from apple and pyracantha to loquat. These findings support a scenario of recent divergence in allopatry followed by introgression through secondary contact, with groups from loquat and pyracantha being the most recently differentiated.
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Affiliation(s)
- P Gladieux
- INRA, UMR 077, 42 rue George Morel, Beaucouzé, France.
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Maroja LS, Andrés JA, Harrison RG. Genealogical discordance and patterns of introgression and selection across a cricket hybrid zone. Evolution 2009; 63:2999-3015. [PMID: 19619226 DOI: 10.1111/j.1558-5646.2009.00767.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In recently diverged species, ancestral polymorphism and introgression can cause incongruence between gene and species trees. In the face of hybridization, few genomic regions may exhibit reciprocal monophyly, and these regions, usually evolving rapidly under selection, may be important for the maintenance of species boundaries. In animals with internal fertilization, genes encoding seminal protein are candidate barrier genes. Recently diverged hybridizing species such as the field crickets Gryllus firmus and G. pennsylvanicus, offer excellent opportunities to investigate the origins of barriers to gene exchange. These recently diverged species form a well-characterized hybrid zone, and share ancestral polymorphisms across the genome. We analyzed DNA sequence divergence for seminal protein loci, housekeeping loci, and mtDNA, using a combination of analytical approaches and extensive sampling across both species and the hybrid zone. We report discordant genealogical patterns and differential introgression rates across the genome. The most dramatic outliers, showing near-zero introgression and more structured species trees, are also the only two seminal protein loci under selection. These are candidate barrier genes with possible reproductive functions. We also use genealogical data to examine the demographic history of the field crickets and the current structure of the hybrid zone.
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Affiliation(s)
- Luana S Maroja
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA.
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MAROJA LUANAS, ANDRÉS JOSEA, WALTERS JAMESR, HARRISON RICHARDG. Multiple barriers to gene exchange in a field cricket hybrid zone. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01201.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Vaezi J, Brouillet L. Phylogenetic relationships among diploid species of Symphyotrichum (Asteraceae: Astereae) based on two nuclear markers, ITS and GAPDH. Mol Phylogenet Evol 2009; 51:540-53. [PMID: 19289175 DOI: 10.1016/j.ympev.2009.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 02/15/2009] [Accepted: 03/06/2009] [Indexed: 10/21/2022]
Abstract
The mostly North American subtribe Symphyotrichinae (Asteraceae: Astereae) comprises Canadanthus, Ampelaster, Psilactis, Almutaster, and Symphyotrichum. Intergeneric and interspecific relationships within the subtribe have been investigated in the past, particularly by Nesom [Nesom, G.L., 1994. Review of the taxonomy of Aster sensu lato (Asteraceae: Astereae), emphasizing the new world species, Phytologia 77, 141-297] and Semple [Semple, J.C., 2005. Classification of Symphyotrichum. Available from: <http://www.jcsemple.uwaterloo.ca/Symphyotrichumclassification.htm/>], using morphological and cytological approaches. Symphyotrichum is the largest and most complex genus within the subtribe and includes four subgenera: Symphyotrichum (x=7, 8), Virgulus (x=4, 5), Astropolium (x=5), and Chapmaniani (x=7). In this study we used two nuclear markers, the nrDNA internal transcribed spacer (ITS) and the low-copy nuclear gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH), to resolve intergeneric and interspecific relationships within the subtribe at the diploid level, and to determine whether our phylogenies validate the classifications of Nesom or Semple. Our results confirm the distinct generic status of Canadanthus and Ampelaster, whereas Psilactis and Almutaster form a polytomy with Symphyotrichum. Within Symphyotrichum, subg. Virgulus is monophyletic based on ITS and appears polyphyletic based on GAPDH. Neither the ITS nor the GAPDH analyses support a distinct status for subg. Astropolium, which groups within subg. Symphyotrichum. In general, interspecific relationships within Symphyotrichum are unresolved. Lack of resolution may be interpreted as a case of recent and rapid evolutionary radiation.
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Affiliation(s)
- Jamil Vaezi
- Dép Sciences Biologiques, Herbier Marie-Victorin, Institut de recherche en Biologie Végétale Université de Montréal, Montréal, Que, Canada.
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36
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Affiliation(s)
- Patrik Nosil
- Zoology Department and Biodiversity Research Centre, University of British Columbia, Vancouver BC, Canada.
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SEQUEIRA FERNANDO, ALEXANDRINO JOÃO, WEISS STEVEN, FERRAND NUNO. Documenting the advantages and limitations of different classes of molecular markers in a well-established phylogeographic context: lessons from the Iberian endemic Golden-striped salamander, Chioglossa lusitanica (Caudata: Salamandridae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2008.01060.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pettengill JB, Neel MC. Phylogenetic patterns and conservation among North American members of the genus Agalinis (Orobanchaceae). BMC Evol Biol 2008; 8:264. [PMID: 18822144 PMCID: PMC2564944 DOI: 10.1186/1471-2148-8-264] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 09/26/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND North American Agalinis Raf. species represent a taxonomically challenging group and there have been extensive historical revisions at the species, section, and subsection levels of classification. The genus contains many rare species, including the federally listed endangered species Agalinis acuta. In addition to evaluating the degree to which historical classifications at the section and subsection levels are supported by molecular data sampled from 79 individuals representing 29 Agalinis species, we assessed the monophyly of 27 species by sampling multiple individuals representing different populations of those species. Twenty-one of these species are of conservation concern in at least some part of their range. RESULTS Phylogenetic relationships estimated using maximum likelihood analyses of seven chloroplast DNA loci (aligned length = 11,076 base pairs (bp) and the nuclear ribosomal DNA ITS (internal transcribed spacer) locus (733 bp); indicated no support for the historically recognized sections except for Section Erectae. Our results suggest that North American members of the genus comprise six major lineages, however we were not able to resolve branching order among many of these lineages. Monophyly of 24 of the 29 sampled species was supported based on significant branch lengths of and high bootstrap support for subtending branches. However, there was no statistical support for the monophyly of A. acuta with respect to Agalinis tenella and Agalinis decemloba. Although most species were supported, deeper relationships among many species remain ambiguous. CONCLUSION The North American Agalinis species sampled form a well supported, monophyletic group within the family Orobanchaceae relative to the outgroups sampled. Most hypotheses regarding section- and subsection-level relationships based on morphology were not supported and taxonomic revisions are warranted. Lack of support for monophyly of Agalinis acuta leaves the important question regarding its taxonomic status unanswered. Lack of resolution is potentially due to incomplete lineage sorting of ancestral polymorphisms among recently diverged species; however the gene regions examined did distinguish among almost all other species in the genus. Due to the important policy implications of this finding we are further evaluating the evolutionary distinctiveness of A. acuta using morphological data and loci with higher mutation rates.
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Affiliation(s)
- James B Pettengill
- Behavior, Ecology, Evolution, and Systematics Graduate Program, University of Maryland College Park, College Park, MD 20742 USA
| | - Maile C Neel
- Behavior, Ecology, Evolution, and Systematics Graduate Program, University of Maryland College Park, College Park, MD 20742 USA
- Department of Plant Science and Landscape Architecture and Department of Entomology, University of Maryland College Park, College Park, MD 20742 USA
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Andrés JA, Maroja LS, Harrison RG. Searching for candidate speciation genes using a proteomic approach: seminal proteins in field crickets. Proc Biol Sci 2008; 275:1975-83. [PMID: 18495616 PMCID: PMC2596363 DOI: 10.1098/rspb.2008.0423] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 04/22/2008] [Accepted: 04/24/2008] [Indexed: 11/12/2022] Open
Abstract
In many animals, male seminal proteins influence gamete interactions and fertilization ability and are probably involved in barriers to gene flow between diverging lineages. Here we use a proteomic approach to identify seminal proteins that are transferred to females during copulation and that may be involved in fertilization barriers between two hybridizing field crickets (Gryllus firmus and Gryllus pennsylvanicus). Analyses of patterns of divergence suggest that much of the field cricket genome has remained undifferentiated following the evolution of reproductive isolation. By contrast, seminal protein genes are highly differentiated. Tests of selection reveal that positive selection is likely to be responsible for patterns of differentiation. Together, our observations suggest that some of the loci encoding seminal proteins may indeed play a role in fertilization barriers in field crickets.
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Affiliation(s)
- Jose A Andrés
- Department of Ecology and Evolutionary Biology, Cornell UniversityIthaca, NY 14853, USA
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Gray DA, Huang H, Knowles LL. Molecular evidence of a peripatric origin for two sympatric species of field crickets (Gryllus rubens and G. texensis) revealed from coalescent simulations and population genetic tests. Mol Ecol 2008; 17:3836-55. [PMID: 18647239 DOI: 10.1111/j.1365-294x.2008.03827.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Species pairs that differ primarily in characters involved in mating interactions and are largely sympatric raise intriguing questions about the mode of speciation. When species divergence is relatively recent, the footprint of the demographic history during speciation might be preserved and used to reconstruct the biogeography of species divergence. In this study, patterns of genetic variation were examined throughout the geographical range of two cryptic sister taxa of field crickets, Gryllus texensis and G. rubens; mitochondrial cytochrome oxidase I (COI) was sequenced in 365 individuals sampled from 48 localities. Despite significant molecular divergence between the species, they were not reciprocally monophyletic. We devised several analyses to statistically explore what historical processes might have given rise to this genealogical structure. The analyses indicated that the biogeographical pattern of genetic variation does not support a model of recent gene flow between species. Instead, coalescent simulations suggested that the genealogical structure within G. texensis, namely a deep split between two geographically overlapping clades, reflects historical substructure within G. texensis. Additional tests that consider the concentration of G. rubens haplotypes in one of the two G. texensis genetic clusters suggest a model of speciation in which G. rubens was derived from one lineage of a geographically subdivided ancestor. These results indicate that, despite the contemporary sympatry of G. texensis and G. rubens, the data are indicative of an peripatric origin in which G. rubens was derived from one of the two historical partitions in the species currently recognized as G. texensis. This proposed model of species divergence suggests how the interplay of geography and selection may give rise to new species, although this requires testing with multilocus data. Specifically, the model highlights how that geographical partitioning of ancestral variation in the past may augment the selectively driven divergence of characters involved in the reproductive isolation of the species today.
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Affiliation(s)
- David A Gray
- Department of Biology, California State University, 18111 Nordhoff Street, Northridge, California 91330-8303, USA.
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41
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Investigating hybridization in the parthenogenetic New Zealand stick insect Acanthoxyla (Phasmatodea) using single-copy nuclear loci. Mol Phylogenet Evol 2008; 48:335-49. [DOI: 10.1016/j.ympev.2008.02.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 02/12/2008] [Accepted: 02/15/2008] [Indexed: 11/19/2022]
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Abstract
We introduce a statistic, the genealogical sorting index (gsi), for quantifying the degree of exclusive ancestry of labeled groups on a rooted genealogy and demonstrate its application. The statistic is simple, intuitive, and easily calculated. It has a normalized range to facilitate comparisons among different groups, trees, or studies and it provides information on individual groups rather than a composite measure for all groups. It naturally handles polytomies and accommodates measures of uncertainty in phylogenetic relationships. We use coalescent simulations to explore the behavior of the gsi across a range of divergence times, with the mean value increasing to 1, the maximum value when exclusivity within a group reached monophyly. Simulations also demonstrate that the power to reject the null hypothesis of mixed genealogical ancestry increased markedly as sample size increased, and that the gsi provides a statistically more powerful measure of divergence than FST. Applications to data from published studies demonstrated that the gsi provides a useful way to detect significant exclusivity even when groups are not monophyletic. Although we describe this statistic in the context of divergence, it is more broadly applicable to quantify and assess the significance of clustering of observations in labeled groups on any tree.
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Affiliation(s)
- Michael P Cummings
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland 20742, USA.
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Good JM, Hird S, Reid N, Demboski JR, Steppan SJ, Martin-Nims TR, Sullivan J. Ancient hybridization and mitochondrial capture between two species of chipmunks. Mol Ecol 2008; 17:1313-27. [PMID: 18302691 DOI: 10.1111/j.1365-294x.2007.03640.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Models that posit speciation in the face of gene flow are replacing classical views that hybridization is rare between animal species. We use a multilocus approach to examine the history of hybridization and gene flow between two species of chipmunks (Tamias ruficaudus and T. amoenus). Previous studies have shown that these species occupy different ecological niches and have distinct genital bone morphologies, yet appear to be incompletely isolated reproductively in multiple areas of sympatry. We compared data from four sequenced nuclear loci and from seven microsatellite loci to published cytochrome b sequences. Interspecific gene flow was primarily restricted to introgression of the T. ruficaudus mitochondrial genome into a sympatric subspecies of T. amoenus, T. a. canicaudus, with the four sequenced nuclear loci showing little to no interspecific allele sharing. Microsatellite data were consistent with high levels of differentiation between the species and also showed no current gene flow between broadly sympatric populations of T. a. canicaudus and T. ruficaudus. Coalescent analyses date the mtDNA introgression event from the mid-Pleistocene to late Pliocene. Overall, these data indicate that introgression has had a minimal impact on the nuclear genomes of T. amoenus and T. ruficaudus despite multiple independent hybridization events. Our findings challenge long-standing assumptions on patterns of reproductive isolation in chipmunks and suggest that there may be other examples of hybridization among the 23 species of Tamias that occur in western North America.
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Affiliation(s)
- Jeffrey M Good
- Department of Ecology and Evolutionary Biology, University of Arizona, Biosciences West, Tucson, AZ 85721, USA
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Population genetics of speciation in two closely related wild tomatoes (Solanum section Lycopersicon). Genetics 2008; 178:339-50. [PMID: 18202377 DOI: 10.1534/genetics.107.081810] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a multilocus sequencing study to assess patterns of polymorphism and divergence in the closely related wild tomato species, Solanum peruvianum and S. chilense (Solanum section Lycopersicon, Solanaceae). The data set comprises seven mapped nuclear loci (approximately 9.3 kb of analyzed sequence across loci) and four local population samples per species that cover much of the species' range (between 80 and 88 sequenced alleles across both species). We employ the analytical framework of divergence population genetics (DPG) in evaluating the utility of the "isolation" model of speciation to explain observed patterns of polymorphism and divergence. Whereas the isolation model is not rejected by goodness-of-fit criteria established via coalescent simulations, patterns of intragenic linkage disequilibrium provide evidence for postdivergence gene flow at two of the seven loci. These results suggest that speciation occurred under residual gene flow, implying that natural selection is one of the evolutionary forces driving the divergence of these tomato species. This inference is fully consistent with their recent divergence, conservatively estimated to be <or=0.55 million years. We discuss possible biases in the demographic parameter estimates due to the current restriction of DPG algorithms to panmictic species.
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Tomozawa M, Suzuki H. A Trend of Central Versus Peripheral Structuring in Mitochondrial and Nuclear Gene Sequences of the Japanese Wood Mouse, Apodemus speciosus. Zoolog Sci 2008; 25:273-85. [DOI: 10.2108/zsj.25.273] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 12/09/2007] [Indexed: 11/17/2022]
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Ghiselli F, Milani L, Scali V, Passamonti M. TheLeptynia hispanicaspecies complex (Insecta Phasmida): polyploidy, parthenogenesis, hybridization and more. Mol Ecol 2007; 16:4256-68. [PMID: 17725570 DOI: 10.1111/j.1365-294x.2007.03471.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Leptynia hispanica stick insect species complex includes bisexuals, triploid and tetraploid parthenogenetic populations, suggesting that polyploidy has played a central role in the evolution of this complex. An analysis of karyotype, mitochondrial DNA (cox2) and nuclear DNA (ef1-alpha) markers was carried out to clarify phylogenetic relationships and microevolutionary/phylogeographical patterns of the L. hispanica complex. Our analyses suggested a subdivision of bisexual populations into four groups, tentatively proposed as incipient species. Moreover, triploids and tetraploids showed two independent origins, the latter being more ancient than the former. From ef1-alpha analysis, triploids showed hybrid constitution, while the hybrid constitution of tetraploids is likely, but more data are needed. We suggest that L. hispanica is a case of 'geographical parthenogenesis' with parthenogenetic strains colonizing large peripheral ranges, and bisexuals confined to glacial refuge areas. Moreover, the age, wide distribution and competitive advantage of polyploids over diploids, demonstrate their significance in the evolution of the L. hispanica species complex.
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Affiliation(s)
- Fabrizio Ghiselli
- Dipartimento di Biologia Evoluzionistica Sperimentale, Università di Bologna, via Selmi 3, I-40126 Bologna, Italy.
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Marshall JL. Rapid evolution of spermathecal duct length in the Allonemobius socius complex of crickets: species, population and Wolbachia effects. PLoS One 2007; 2:e720. [PMID: 17684565 PMCID: PMC1934930 DOI: 10.1371/journal.pone.0000720] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 07/05/2007] [Indexed: 11/18/2022] Open
Abstract
The three species in the Allonemobius socius complex of crickets have recently diverged and radiated across North America. Interestingly, the only barriers to gene flow between these species in zones of secondary contact appear to be associated with fertilization traits - e.g., conspecific sperm precedence and the ability of males to induce females to lay eggs. Other traits, such as the length of female's reproductive tract, may also influence fertilization success and be associated with species boundaries. However, the underlying variation in this duct has not been assessed across populations and species. Moreover, the effects of reproductive parasites like Wolbachia on these morphological features have yet to be addressed, even though its infections are concentrated in reproductive tissues. I evaluated both the natural variation in and the effects of Wolbachia infection on spermathecal duct length among several populations of two species in the Allonemobius socius complex. My results suggest the following: (1) spermathecal duct length varies between species and is associated with species boundaries, (2) there is considerable variation among populations within species, (3) there is a Wolbachia infection-by-population interaction effect on the length of the spermathecal duct, and (4) experimental curing of Wolbachia recovers the uninfected morphology. These findings suggest the following hypotheses: (1) spermathecal duct length, like other fertilization traits in Allonemobius, is evolving rapidly and influences reproductive isolation and (2) Wolbachia-induced modifications of this duct could influence the dynamics of male-female coevolution. Further experiments are needed, however, to explicitly test these latter two hypotheses.
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Affiliation(s)
- Jeremy L Marshall
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America.
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48
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Rank NE, Bruce DA, McMillan DM, Barclay C, Dahlhoff EP. Phosphoglucose isomerase genotype affects running speed and heat shock protein expression after exposure to extreme temperatures in a montane willow beetle. ACTA ACUST UNITED AC 2007; 210:750-64. [PMID: 17297136 DOI: 10.1242/jeb.02695] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Eastern Sierra Nevada populations of the willow beetle Chrysomela aeneicollis commonly experience stressfully high and low environmental temperatures that may influence survival and reproduction. Allele frequencies at the enzyme locus phosphoglucose isomerase (PGI) vary across a climatic latitudinal gradient in these populations, with PGI allele 1 being most common in cooler regions and PGI allele 4 in warmer ones. PGI genotypes differ in heat and cold tolerance and in expression of a 70 kDa heat shock protein. Here we examine genetic, behavioral and environmental factors affecting a performance character, running speed, for willow beetles, and assess effects of consecutive cold and heat exposure on running speed and expression of Hsp70 in the laboratory. In nature, running speed depends on air temperature and is higher for males than females. Mating beetles ran faster than single beetles, and differences among PGI genotypes in male running speed depended on the presence of females. In the laboratory, exposure to cold reduced subsequent running speed, but the amount of this reduction depended on PGI genotype and previous thermal history. Effects of exposure to heat also depended on life history stage and PGI genotype. Adults possessing allele 1 ran fastest after a single exposure to stressful temperature, whereas those possessing allele 4 ran faster after repeated exposure. Larvae possessing allele 4 ran fastest after a single stressful exposure, but running speed generally declined after a second exposure to stressful temperature. The ranking of PGI genotypes after the second exposure depended on whether a larva had been exposed to cold or heat. Effects of temperature on Hsp70 expression also varied among PGI genotypes and depended on type of exposure, especially for adults (single heat exposure, two cold exposures: PGI 1-1>1-4>4-4; other multiple extreme exposures: 4-4>1-4>1-1). There was no consistent association between alleles at other polymorphic enzyme loci and running speed or Hsp70 expression. These data suggest that variation at PGI is associated with considerable plasticity in running speed. Differences in Hsp70 expression among PGI genotypes suggest that the heat-shock response may buffer differences in thermal tolerance and performance among genotypes and help maintain the PGI polymorphism in a thermally variable environment.
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Affiliation(s)
- Nathan E Rank
- Department of Biology, Sonoma State University, Rohnert Park, CA 94928, USA.
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Malausa T, Leniaud L, Martin JF, Audiot P, Bourguet D, Ponsard S, Lee SF, Harrison RG, Dopman E. Molecular differentiation at nuclear loci in French host races of the European corn borer (Ostrinia nubilalis). Genetics 2007; 176:2343-55. [PMID: 17603115 PMCID: PMC1950636 DOI: 10.1534/genetics.107.072108] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
French populations of the European corn borer consist of two sympatric and genetically differentiated host races. As such, they are well suited to study processes that could be involved in sympatric speciation, but the initial conditions of host-race divergence need to be elucidated. Gene genealogies can provide insight into the processes involved in speciation. We used DNA sequences of four nuclear genes to (1) document the genetic structure of the two French host races previously delineated with allozyme markers, (2) find genes directly or indirectly involved in reproductive isolation between host races, and (3) estimate the time since divergence of the two taxa and see whether this estimate is compatible with this divergence being the result of a host shift onto maize after its introduction into Europe approximately 500 years ago. Gene genealogies revealed extensive shared polymorphism, but confirmed the previously observed genetic differentiation between the two host races. Significant departures from the predictions of neutral molecular evolution models were detected at three loci but were apparently unrelated to reproductive isolation between host races. Estimates of time since divergence between French host races varied from approximately 75,000 to approximately 150,000 years, suggesting that the two taxa diverged recently but probably long before the introduction of maize into Europe.
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Affiliation(s)
- Thibaut Malausa
- Laboratoire Dynamique de la Biodiversité, UMR CNRS 5172, Université P. Sabatier-Toulouse III, 118 Route de Narbonne, 31 062 Toulouse Cedex 09, france.
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Mullen SP, Andrés JA. Rapid evolution of sexual signals in sympatric Calopteryx damselflies: reinforcement or ?noisy-neighbour? ecological character displacement? J Evol Biol 2007; 20:1637-48. [PMID: 17584256 DOI: 10.1111/j.1420-9101.2007.01297.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enhanced prezygotic isolation in sympatry is one of the most intriguing patterns in evolutionary biology and has frequently been interpreted as evidence for reinforcement. However, the frequency with which reinforcement actually completes speciation remains unclear. The Jewelwing damselflies (Calopteryx aequabilis and C. maculata) have served as one of the few classic examples of speciation via reinforcement outside of Drosophila. Although evidence for wing pattern displacement and increased mate discrimination in this system have been demonstrated, the degree of hybridization and gene flow in nature are unknown. Here, we show that sympatric populations of these two species are the result of recent secondary contact, as predicted under a model of speciation via reinforcement. However, we found no phenotypic evidence of hybridization in natural populations and a complete association between species-specific haplotypes at two different loci (mitochondrial CO I and nuclear EF1-alpha), suggesting little or no contemporary gene flow. Moreover, genealogical and coalescent-based estimates of divergence times and migration rates indicate that, speciation occurred in the distant past. The rapid evolution of wing colour in sympatry is recent, therefore, relative to speciation and seems to be better explained by selection against wasting mating effort and/or interspecific aggression resulting from a 'noisy neighbour' signalling environment.
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Affiliation(s)
- S P Mullen
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA.
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