Molecular evidence for dispersal rather than vicariance as the origin of flightless insect species on the Chatham Islands, New Zealand
Article first published online: 24 DEC 2001
Journal of Biogeography
Volume 27, Issue 5, pages 1189–1200, September 2000
How to Cite
Trewick, S. A. (2000), Molecular evidence for dispersal rather than vicariance as the origin of flightless insect species on the Chatham Islands, New Zealand. Journal of Biogeography, 27: 1189–1200. doi: 10.1046/j.1365-2699.2000.00492.x
- Issue published online: 24 DEC 2001
- Article first published online: 24 DEC 2001
- Chatham Islands;
- New Zealand;
The aim was to use mitochondrial DNA sequence data to test between vicariance and oversea dispersal explanations for the origin of the Chatham Islands biota.
New Zealand and the Chatham Islands, separated by c. 800 km in the south-west Pacific Ocean.
DNA sequences from the mitochondrial gene cytochrome oxidase I (COI) were obtained from four genera of relatively large and flightless insects (Coleoptera— Geodorcus, Mecodema; Orthoptera—Talitropsis; Blattoidea—Celatoblatta). These were used to test alternative hypotheses for the origin of the Chatham taxa.
Phylogenetic analysis revealed the Chatham taxa in each genus to be monophyletic. Genetic distances exhibited by these genera, between taxa found on the Chatham Islands and mainland New Zealand were relatively low (11.2, 2.8, 3.0 and 4.9%, respectively).
Even allowing for variation in molecular evolutionary rates, these genetic distances indicate phylogenetic separation of New Zealand and Chatham insect lineages in the Pliocene (2–6 Ma). Such dates are more than one order of magnitude too recent to be explained by vicariant (tectonic) processes. Oversea dispersal from New Zealand to the Chatham Islands is implicated and this conclusion is in keeping with the taxonomy of the endemic avifauna, flora and fossil molluscan fauna.