Molecular evidence for Gondwanan origins of multiple lineages within a diverse Australasian gecko radiation

Abstract

Aim Gondwanan lineages are a prominent component of the Australian terrestrial biota. However, most squamate (lizard and snake) lineages in Australia appear to be derived from relatively recent dispersal from Asia (< 30 Ma) and in situ diversification, subsequent to the isolation of Australia from other Gondwanan landmasses. We test the hypothesis that the Australian radiation of diplodactyloid geckos (families Carphodactylidae, Diplodactylidae and Pygopodidae), in contrast to other endemic squamate groups, has a Gondwanan origin and comprises multiple lineages that originated before the separation of Australia from Antarctica. Location Australasia. Methods Bayesian (beast) and penalized likelihood rate smoothing (PLRS) (r8s) molecular dating methods and two long nuclear DNA sequences (RAG‐1 and c‐mos) were used to estimate a timeframe for divergence events among 18 genera and 30 species of Australian diplodactyloids. Results At least five lineages of Australian diplodactyloid geckos are estimated to have originated > 34 Ma (pre‐Oligocene) and basal splits among the Australian diplodactyloids occurred c. 70 Ma. However, most extant generic and intergeneric diversity within diplodactyloid lineages appears to post‐date the late Oligocene (< 30 Ma). Main conclusions Basal divergences within the diplodactyloids significantly pre‐date the final break‐up of East Gondwana, indicating that the group is one of the most ancient extant endemic vertebrate radiations east of Wallace’s Line. At least five Australian lineages of diplodactyloid gecko are each as old or older than other well‐dated Australian squamate radiations (e.g. elapid snakes and agamids). The limbless Pygopodidae (morphologically the most aberrant living geckos) appears to have radiated before Australia was occupied by potential ecological analogues. However, in spite of the great age of the diplodactyloid radiation, most extant diversity appears to be of relatively recent origin, a pattern that is shared with other Australian squamate lineages.

New Zealand geckos (Diplodactylidae): Cryptic diversity in a post-Gondwanan lineage with trans-Tasman affinities

“…5). Although the Diplodactylidae as a whole is well supported only under BI (ML = 49%, BI = 1.0, MP = 50%), other recent studies have provided further support for its monophyly (Gamble et al, 2008a,b: Oliver andSanders, 2009). The monophyly of the New Zealand geckos is well supported by all analyses (ML = 99%, BI = 1.0, MP = 100%) and there is a deep divergence (up to 16% divergence across all genes) between the New Zealand clade and its immediate sister group, comprising Australian diplodactylids exclusive of Pseudothecadactylus, which is the sister to the monophyletic New Caledonian diplodactylid radiation.…”

“…3 and 4). Species for outgroup comparison included representative species from the families Carphodactylidae and Pygopodidae, which together constitute the sister group to the Diplodactylidae (Han et al, 2004;Gamble et al, 2008a,b;Oliver and Sanders, 2009). Representative Australian and New Caledonian diplodactylids were also included as ingroup taxa in order to assess the monophyly of the New Zealand taxa as a group.…”

Evaluating evolutionary history in the face of high gene tree discordance in Australian Gehyra (Reptilia: Gekkonidae)

“…Therefore, the invasion of a tropically adapted, ancestral Gehyra from the Melanesian region at this time is plausible and supported by our ancestral state reconstruction analysis. In contrast with the other Australian Gekkotan lineages which have a Gondwanan origin, the divergence between Australian and Melanesian Gehyra is more recent (Gamble et al, 2008b;Oliver and Sanders, 2009) as is consequently the diversification within Australian Gehyra.…”

“…All non-Gehyra sequences were obtained from Genbank. Monophyly of the Gekkotans in relation to other squamates is well established (for example, Gamble et al, 2010, Oliver andSanders, 2009) and was thus assumed a priori. Model selection was determined using the Akaike Information Criterion (AIC) carried out using jModeltest v0.1.1 (Posada, 2008).…”

“…Output was evaluated using TRACER v1.4.1 (Drummond and Rambaut, 2010) to confirm acceptable mixing, stationarity of the MCMC parameter sampling and adequate effective sample sizes (4500). Due to the lack of Gekkotan fossils, which can be placed with enough phylogenetic precision to act as molecular clock calibrations (Sanders et al, 2008;Oliver and Sanders, 2009;Gamble et al, 2010), a number of robust external fossil calibrations were used. Our chosen calibrations are similar to those of Sanders et al (2008) and are summarized in Table 2.…”