The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kevin De Queiroz - One of the best experts on this subject based on the ideXlab platform.
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phylogeography and monophyly of the swordtail fish species xiphophorus birchmanni Cyprinodontiformes poeciliidae
Zoologica Scripta, 2008Co-Authors: Carla Gutierrezrodriguez, Molly R. Morris, Eliot A Shearer, Kevin De QueirozAbstract:We used sequences of the mitochondria control region to assess the distribution of genetic variation within and among populations of the poeciliid fish species Xiphophorus birchmanni. We collected 122 X. birchmanni samples from 11 sites in three drainage systems comprising the distribution of the species. We found low levels of polymorphism among aligned sequences and low levels of genetic variation within populations but high levels of genetic differentiation among populations. Haplotypes are exclusive to three river drainages (Los Hules, Calabozo and San Pedro). Mantel tests revealed correlations between geographical (both straight-line and river distances) and genetic distance, consistent with an isolation by distance scenario, while nested clade analysis suggested allopatric fragmentation between haplotypes from two of the major drainages, and isolation by distance with restricted gene flow within those drainages. Finally, monophyly of X. birchmanni is strongly supported while the previous hypothesis of the evolutionary origin of this species from X. malinche is not.
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Genetic variation and phylogeography of the swordtail fish Xiphophorus cortezi (Cyprinodontiformes, Poeciliidae).
Molecular phylogenetics and evolution, 2006Co-Authors: Carla Gutiérrez-rodríguez, Molly R. Morris, Natalie S. Dubois, Kevin De QueirozAbstract:Swordtail fish have been studied extensively in relation to diverse aspects of biology; however, little attention has been paid to the patterns of genetic variation within and among populations of swordtails. In this study, we sequenced the mtDNA control region from 65 individuals and 10 populations of Xiphophorus cortezi to investigate the genetic variation within and among populations, including tests for correlations between genetic and geographic distances and tests for species monophyly. We found low gene and nucleotide diversity within populations and high degrees of genetic differentiation among populations. Significant and positive correlations between genetic distance and both river and straight-line geographic distance indicate that genetic differentiation among X. cortezi populations can be explained, to some extent, by an isolation-by-distance model and provide evidence of stream capture. Phylogenetic analyses suggest that X. cortezi is paraphyletic relative to X. malinche, raising questions concerning the status of these taxa as separate species.
Jan Klein - One of the best experts on this subject based on the ideXlab platform.
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persistence of mhc heterozygosity in homozygous clonal killifish rivulus marmoratus implications for the origin of hermaphroditism
Genetics, 2002Co-Authors: Akie Sato, Yoko Satta, Felipe Figueroa, Werner E Mayer, Zofia Zaleskarutczynska, Satoru Toyosawa, Joseph Travis, Jan KleinAbstract:The mangrove killifish Rivulus marmoratus, a neotropical fish in the order Cyprinodontiformes, is the only known obligatorily selfing, synchronous hermaphroditic vertebrate. To shed light on its population structure and the origin of hermaphroditism, major histocompatibility complex (Mhc) class I genes of the killifish from seven different localities in Florida, Belize, and the Bahamas were cloned and sequenced. Thirteen loci and their alleles were identified and classified into eight groups. The loci apparently arose ∼20 million years ago (MYA) by gene duplications from a single common progenitor in the ancestors of R. marmoratus and its closest relatives. Distinct loci were found to be restricted to different populations and different individuals in the same population. Up to 44% of the fish were heterozygotes at Mhc loci, as compared to near homozygosity at non-Mhc loci. Large genetic distances between some of the Mhc alleles revealed the presence of ancestral allelic lineages. Computer simulation designed to explain these findings indicated that selfing is incomplete in R. marmoratus populations, that Mhc allelic lineages must have diverged before the onset of selfing, and that the hermaphroditism arose in a population containing multiple ancestral Mhc lineages. A model is proposed in which hermaphroditism arose stage-wise by mutations, each of which spread through the entire population and was fixed independently in the emerging clones.
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mhc class i genes of swordtail fishes xiphophorus variation in the number of loci and existence of ancient gene families
Immunogenetics, 2001Co-Authors: Felipe Figueroa, Akie Sato, Werner E Mayer, Zofia Zaleskarutczynska, Beate Hess, Herbert Tichy, Jan KleinAbstract:Swordtail fishes and platies in the genus Xiphophorus (order Cyprinodontiformes, Teleostei) encompass 22 closely related species which are the products of a recent adaptive radiation in the streams of Central America. To investigate the evolution of the major histocompatibility complex (Mhc) genes in the period immediately following speciation, the class I genes from 20 of the 22 species were cloned and characterized by sequencing. The analysis revealed the existence of multiple loci (at least seven in some individuals) whose numbers vary among the different species and probably also among individuals of the same species. The variation does not seem to bear any relationship to the taxonomy of the genus. Genes at the different loci are distinguished by their intron sequences and by the presence of characteristic motifs in exons 2 and 3. The variation in copy number of loci may have been effected in part by unequal crossing over occurring between introns of misaligned closely related genes. The sequences of the genes fall into two groups, A and B, which represent ancient lineages. The groups define two families of loci, which diverged from each other an estimated 85 million years ago, before the separation of the Acanthopterygii from the Paracanthopterygii of the advanced bony fishes. Evolution of the genes within each family can be explained by the birth-and-death process driven by gene duplications and mutational differentiation.
Molly R. Morris - One of the best experts on this subject based on the ideXlab platform.
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phylogeography and monophyly of the swordtail fish species xiphophorus birchmanni Cyprinodontiformes poeciliidae
Zoologica Scripta, 2008Co-Authors: Carla Gutierrezrodriguez, Molly R. Morris, Eliot A Shearer, Kevin De QueirozAbstract:We used sequences of the mitochondria control region to assess the distribution of genetic variation within and among populations of the poeciliid fish species Xiphophorus birchmanni. We collected 122 X. birchmanni samples from 11 sites in three drainage systems comprising the distribution of the species. We found low levels of polymorphism among aligned sequences and low levels of genetic variation within populations but high levels of genetic differentiation among populations. Haplotypes are exclusive to three river drainages (Los Hules, Calabozo and San Pedro). Mantel tests revealed correlations between geographical (both straight-line and river distances) and genetic distance, consistent with an isolation by distance scenario, while nested clade analysis suggested allopatric fragmentation between haplotypes from two of the major drainages, and isolation by distance with restricted gene flow within those drainages. Finally, monophyly of X. birchmanni is strongly supported while the previous hypothesis of the evolutionary origin of this species from X. malinche is not.
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Genetic variation and phylogeography of the swordtail fish Xiphophorus cortezi (Cyprinodontiformes, Poeciliidae).
Molecular phylogenetics and evolution, 2006Co-Authors: Carla Gutiérrez-rodríguez, Molly R. Morris, Natalie S. Dubois, Kevin De QueirozAbstract:Swordtail fish have been studied extensively in relation to diverse aspects of biology; however, little attention has been paid to the patterns of genetic variation within and among populations of swordtails. In this study, we sequenced the mtDNA control region from 65 individuals and 10 populations of Xiphophorus cortezi to investigate the genetic variation within and among populations, including tests for correlations between genetic and geographic distances and tests for species monophyly. We found low gene and nucleotide diversity within populations and high degrees of genetic differentiation among populations. Significant and positive correlations between genetic distance and both river and straight-line geographic distance indicate that genetic differentiation among X. cortezi populations can be explained, to some extent, by an isolation-by-distance model and provide evidence of stream capture. Phylogenetic analyses suggest that X. cortezi is paraphyletic relative to X. malinche, raising questions concerning the status of these taxa as separate species.
Felipe Figueroa - One of the best experts on this subject based on the ideXlab platform.
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persistence of mhc heterozygosity in homozygous clonal killifish rivulus marmoratus implications for the origin of hermaphroditism
Genetics, 2002Co-Authors: Akie Sato, Yoko Satta, Felipe Figueroa, Werner E Mayer, Zofia Zaleskarutczynska, Satoru Toyosawa, Joseph Travis, Jan KleinAbstract:The mangrove killifish Rivulus marmoratus, a neotropical fish in the order Cyprinodontiformes, is the only known obligatorily selfing, synchronous hermaphroditic vertebrate. To shed light on its population structure and the origin of hermaphroditism, major histocompatibility complex (Mhc) class I genes of the killifish from seven different localities in Florida, Belize, and the Bahamas were cloned and sequenced. Thirteen loci and their alleles were identified and classified into eight groups. The loci apparently arose ∼20 million years ago (MYA) by gene duplications from a single common progenitor in the ancestors of R. marmoratus and its closest relatives. Distinct loci were found to be restricted to different populations and different individuals in the same population. Up to 44% of the fish were heterozygotes at Mhc loci, as compared to near homozygosity at non-Mhc loci. Large genetic distances between some of the Mhc alleles revealed the presence of ancestral allelic lineages. Computer simulation designed to explain these findings indicated that selfing is incomplete in R. marmoratus populations, that Mhc allelic lineages must have diverged before the onset of selfing, and that the hermaphroditism arose in a population containing multiple ancestral Mhc lineages. A model is proposed in which hermaphroditism arose stage-wise by mutations, each of which spread through the entire population and was fixed independently in the emerging clones.
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mhc class i genes of swordtail fishes xiphophorus variation in the number of loci and existence of ancient gene families
Immunogenetics, 2001Co-Authors: Felipe Figueroa, Akie Sato, Werner E Mayer, Zofia Zaleskarutczynska, Beate Hess, Herbert Tichy, Jan KleinAbstract:Swordtail fishes and platies in the genus Xiphophorus (order Cyprinodontiformes, Teleostei) encompass 22 closely related species which are the products of a recent adaptive radiation in the streams of Central America. To investigate the evolution of the major histocompatibility complex (Mhc) genes in the period immediately following speciation, the class I genes from 20 of the 22 species were cloned and characterized by sequencing. The analysis revealed the existence of multiple loci (at least seven in some individuals) whose numbers vary among the different species and probably also among individuals of the same species. The variation does not seem to bear any relationship to the taxonomy of the genus. Genes at the different loci are distinguished by their intron sequences and by the presence of characteristic motifs in exons 2 and 3. The variation in copy number of loci may have been effected in part by unequal crossing over occurring between introns of misaligned closely related genes. The sequences of the genes fall into two groups, A and B, which represent ancient lineages. The groups define two families of loci, which diverged from each other an estimated 85 million years ago, before the separation of the Acanthopterygii from the Paracanthopterygii of the advanced bony fishes. Evolution of the genes within each family can be explained by the birth-and-death process driven by gene duplications and mutational differentiation.
Michael J Ghedotti - One of the best experts on this subject based on the ideXlab platform.
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phylogeny classification and evolution of salinity tolerance of the north american topminnows and killifishes family fundulidae teleostei Cyprinodontiformes
Fieldiana Life and Earth Sciences, 2013Co-Authors: Michael J Ghedotti, Matthew P DavisAbstract:Abstract The North American topminnows and killifishes in the Family Fundulidae (Cyprinodontiformes) are widely distributed in freshwater, brackish, and coastal marine environments of North America, the Yucatan Peninsula, and Bermuda. Fundulid fishes are often found in habitats that undergo substantial variation in environmental conditions. Salinity tolerance of fundulids varies substantially, and some estuarine species can survive in water that is more than three times marine salinity, whereas other freshwater species can only tolerate up to one-third marine salinity. While the Family Fundulidae has been the focus of numerous phylogenetic investigations, their evolutionary relationships to other cyprinodontiforms and the evolutionary history of species within the family are in need of further investigation with robust taxonomic sampling. In this study we provide the most data-inclusive current hypothesis of evolutionary relationships for the Fundulidae, based on a combination of morphological, karyologic...
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phylogenetic analysis and taxonomy of the poecilioid fishes teleostei Cyprinodontiformes
Zoological Journal of the Linnean Society, 2000Co-Authors: Michael J GhedottiAbstract:Abstract Evidence from morphology is used to infer the phylogeny of the superfamily Poecilioidea using other cyprinodontoid fishes as outgroups. The three equally most parsimonious trees resulting from the phylogenetic analysis support the monophyly of the families Anablepidae and Poeciliidae with respect to each other, but the previous taxonomy within the Poeciliinae is not consistent with the resultant phylogenetic trees. The Poeciliidae is recognized with three subfamilies: the Aplocheilichthyinae containing solely Aplocheilichthys spilauchen, the Procatopodinae containing Fluviphylax (Fluviphylacini) and the African lamp-eyed killifishes (Procatopodini), and the Poeciliinae. The inferred hierarchical relationships of included suprageneric taxa are: ((Oxyzygonectinae, Anablepinae) (Aplocheilichthyinae ((Fluviphylacini, Procatopodini) (Alfarini (Priapellini (Gambusini (Heterandrini (Cnesterodontini (Girardini, Poeciliini))))))))). The tribe Alfarini is resurrected and a new tribe, the Priapellini, is described. Tomeurus gracilis is not the most basal poeciliine, and facultative viviparity in Tomeurus is not a plesiomorphic intermediate condition of viviparity retained from the common ancestor of poeciliines. Facultative viviparity in Tomeurus is the result of an evolutionary loss of obligate viviparity.Tomeurus gracilis is recognized as a member of the tribe Cnesterodontini. Lamprichthys tanganicus andMicropanchax pelagicus are not sister taxa, and the pelagic lacustrine habits of these two species are inferred to have evolved independently. Based on the principles of vicariance biogeography, the origin of the Poecilioidea is inferred to have occurred before the separation of Africa and South America.
