A mitochondrial DNA phylogeny of African clawed frogs: Phylogeography and implications for polyploid evolution

Ben J. Evans*, Darcy B. Kelley, Richard C. Tinsley, Don J. Melnick, David C. Cannatella

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

219 Citations (Scopus)

Abstract

The African clawed frogs (Silurana and Xenopus), model organisms for scientific inquiry, are unusual in that allopolyploidization has occurred on multiple occasions, giving rise to tetraploid, octoploid, and dodecaploid species. To better understand their evolution, here we estimate a mitochondrial DNA phylogeny from all described and some undescribed species. We examine the timing and location of diversification, and test hypotheses concerning the frequency of polyploid speciation and taxonomy. Using a relaxed molecular clock, we estimate that extant clawed frog lineages originated well after the breakup of Gondwana, about 63.7 million years ago, with a 95% confidence interval from 50.4 to 81.3 million years ago. Silurana and two major lineages of Xenopus have overlapping distributions in sub-Saharan Africa, and dispersal-vicariance analysis suggests that clawed frogs originated in central and/or eastern equatorial Africa. Most or all extant species originated before the Pleistocene; recent rainforest refugia probably acted as "lifeboats" that preserved existing species, rather than "species pumps" where many new successful lineages originated. We estimate that polyploidization occurred at least six times in clawed frogs.

Original languageEnglish
Pages (from-to)197-213
Number of pages17
JournalMolecular Phylogenetics and Evolution
Volume33
Issue number1
DOIs
Publication statusPublished - 1 Oct 2004

Keywords

  • Genome duplication
  • Hybridization
  • Pipidae
  • Polyploidy
  • Rainforest refugia
  • Silurana
  • Xenopus

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