Phylogeographic history and gene flow among giant Galápagos tortoises on southern Isabela island

Claudio Ciofi*, Gregory A. Wilson, Luciano B. Beheregaray, Cruz Marquez, James P. Gibbs, Washington Tapia, Howard L. Snell, Adalgisa Caccone, Jeffrey R. Powell

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    38 Citations (Scopus)

    Abstract

    Volcanic islands represent excellent models with which to study the effect of vicariance on colonization and dispersal, particularly when the evolution of genetic diversity mirrors the sequence of geological events that led to island formation. Phylogeographic inference, however, can be particularly challenging for recent dispersal events within islands, where the antagonistic effects of land bridge formation and vicariance can affect movements of organisms with limited dispersal ability. We investigated levels of genetic divergence and recovered signatures of dispersal events for 631 Galápagos giant tortoises across the volcanoes of Sierra Negra and Cerro Azul on the island of Isabela. These volcanoes are among the most recent formations in the Galápagos (<0.7 million years), and previous studies based on genetic and morphological data could not recover a consistent pattern of lineage sorting. We integrated nested clade analysis of mitochondrial DNA control region sequences, to infer historical patterns of colonization, and a novel Bayesian multilocus genotyping method for recovering evidence of recent migration across volcanoes using eleven microsatellite loci. These genetic studies illuminate taxonomic distinctions as well as provide guidance to possible repatriation programs aimed at countering the rapid population declines of these spectacular animals.

    Original languageEnglish
    Pages (from-to)1727-1744
    Number of pages18
    JournalGenetics
    Volume172
    Issue number3
    DOIs
    Publication statusPublished - Mar 2006

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