The shifting roles of dispersal and vicariance in biogeography

Robert M Zink, Rachelle C. Blackwell-Rago, Fredrik Ronquist

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


Dispersal and vicariance are often contrasted as competing processes primarily responsible for spatial and temporal patterns of biotic diversity. Recent methods of biogeographical reconstruction recognize the potential of both processes, and the emerging question is about discovering their relative frequencies. Relatively few empirical studies, especially those employing molecular phylogenies that allow a temporal perspective, have attempted to estimate the relative roles of dispersal and vicariance. In this study, the frequencies of vicariance and dispersal were estimated in six lineages of birds that occur mostly in the aridlands of North America. Phylogenetic trees derived from mitochondrial DNA sequence data were compared for towhees (genus Pipilo), gnatcatchers (genus Polioptila), quail (genus Callipepla), warblers (genus Vermivora) and two groups of thrashers (genus Toxostoma). Different area cladograms were obtained depending on how widespread and missing taxa were coded. Nonetheless, no cladogram was obtained for which all lineages were congruent. Although vicariance was the dominant mode of evolution in these birds, approximately 25% of speciation events could have been derived from dispersal across a preexisting barrier. An expanded database is now needed to estimate the relative roles of each process. Applying a molecular clock calibration, nearly all speciation events are of the order of a million or more years old, much older than typically presumed.

Original languageEnglish (US)
Pages (from-to)497-503
Number of pages7
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1442
StatePublished - Mar 7 2000


  • Aridland birds
  • Dispersal
  • Molecular clocks
  • North America
  • Pleistocene
  • Vicariance


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