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Evolutionary history of the fish genus Astyanax Baird & Girard (1854) (Actinopterygii, Characidae) in Mesoamerica reveals multiple morphological homoplasies

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BMC Evolutionary Biology

BioMed Central

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      Abstract

      Background

      Mesoamerica is one of the world's most complex biogeographical regions, mostly due to its complex geological history. This complexity has led to interesting biogeographical processes that have resulted in the current diversity and distribution of fauna in the region. The fish genus Astyanax represents a useful model to assess biogeographical hypotheses due to it being one of the most diverse and widely distributed freshwater fish species in the New World. We used mitochondrial and nuclear DNA to evaluate phylogenetic relationships within the genus in Mesoamerica, and to develop historical biogeographical hypotheses to explain its current distribution.

      Results

      Analysis of the entire mitochondrial cytochrome b (Cytb) gene in 208 individuals from 147 localities and of a subset of individuals for three mitochondrial genes (Cytb, 16 S, and COI) and a single nuclear gene (RAG1) yielded similar topologies, recovering six major groups with significant phylogeographic structure. Populations from North America and Upper Central America formed a monophyletic group, while Middle Central America showed evidence of rapid radiation with incompletely resolved relationships. Lower Central America lineages showed a fragmented structure, with geographically restricted taxa showing high levels of molecular divergence. All Bramocharax samples grouped with their sympatric Astyanax lineages (in some cases even with allopatric Astyanax populations), with less than 1% divergence between them. These results suggest a homoplasic nature to the trophic specializations associated with Bramocharax ecomorphs, which seem to have arisen independently in different Astyanax lineages. We observed higher taxonomic diversity compared to previous phylogenetic studies of the Astyanax genus. Colonization of Mesoamerica by Astyanax before the final closure of the Isthmus of Panama (3.3 Mya) explains the deep level of divergence detected in Lower Central America. The colonization of Upper Mesoamerica apparently occurred by two independent routes, with lineage turnover over a large part of the region.

      Conclusion

      Our results support multiple, independent origins of morphological traits in Astyanax, whereby the morphotype associated with Bramocharax represents a recurrent trophic adaptation. Molecular clock estimates indicate that Astyanax was present in Mesoamerica during the Miocene (~8 Mya), which implies the existence of an incipient land-bridge connecting South America and Central America before the final closure of the Isthmus of Panama (~3.3 Mya).

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      Most cited references 87

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            Author and article information

            Affiliations
            [1]Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, Madrid, Spain
            [2]Posgrado en Ciencias del Mar y Limnología, Instituto de Ciencias del Mar y Limnología, Circuito exterior s/n, Ciudad Universitaria, México DF, Mexico
            Contributors
            Journal
            BMC Evol Biol
            BMC Evolutionary Biology
            BioMed Central
            1471-2148
            2008
            22 December 2008
            : 8
            : 340
            2657800
            1471-2148-8-340
            19102731
            10.1186/1471-2148-8-340
            Copyright © 2008 Ornelas-García et al; licensee BioMed Central Ltd.

            This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

            Categories
            Research Article

            Evolutionary Biology

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