The complex colonization history of nocturnal geckos (Paroedura) in the Comoros Archipelago

Abstract

Hawlitschek, O. & Glaw, F. (2012). The complex colonization history of nocturnal geckos (Paroedura) in the Comoros Archipelago. —Zoologica Scripta, 00, 000–000.Oceanic islands have attracted special attention from evolutionary biologists because their mostly species‐poor, but highly endemic biota are exposed to selection regimes different to those of their mainland relatives. While many groups of oceanic islands worldwide have been used as natural laboratories of evolutionary biology, few such studies have been performed on the Comoros Archipelago in the Western Indian Ocean. We study Paroedura sanctijohannis Günther 1879, a nocturnal gecko endemic to this archipelago as only species of an otherwise Malagasy endemic genus. According to our phylogeny, P. sanctijohannis is not monophyletic, the population of the geologically oldest island Mayotte is clustering with related Malagasy species. We describe this population as Paroedura stellata sp.n. and provide morphological evidence distinguishing it from other Paroedura species. A molecular clock analysis shows that genetic divergence within P. sanctijohannis of the youngest island Grand Comoro is higher than expected based on its geological age. Additionally, this population is paraphyletic with respect to the population of the older island Anjouan, suggesting that the latter island was colonized long after its initial emergence, possibly after extinction of an original Paroedura population. Furthermore, we find that P. stellata sp.n. and P. sanctijohannis are more similar to each other than to other Paroedura species regarding adult coloration and juvenile coloration. Because these two species are not each other’s closest relatives, we discuss possible explanations for this pattern and suggest that it represents convergent adaptation to a relaxed insular selection regime.