Using statistical phylogeography to infer population history: Case studies on Pimelia darkling beetles from the Canary Islands

Sequence data from a 200 bp fragment of the Cytochrome Oxidase I mitochondrial gene was derived from endemic populations of the darkling beetle Pimelia laevigata (Coleoptera, Tenebrionidae) from the volcanic islands of La Gomera, La Palma and El Hierro and from three related congeneric species of Tenerife (Canary Islands). Statistical phylogeographic methods and estimates of demographic parameters suggest that there is a higher genetic variation and geographical structure in two of the Tenerife nominal species than in populations of P. laevigata in the western islands. In La Gomera, La Palma and El Hierro, the patterns are consistent with relatively recent colonizations, followed by range expansions. The results show that hypotheses based on coalescent theory can be useful to reconstruct historic biogeographical events of oceanic islands in a range of different organisms provided that the sample design is adequate and enough genetic resolution is present. However, some specific problems arise when interpreting the inference key applied to the volcanic islands populations.