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

Repeated origin and loss of adhesive toepads in geckos

Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

Little and large: body size and genetic clines in a New Zealand gecko (Woodworthia maculata) along a coastal transect

Clinal variation can result from primary differentiation or secondary contact and determining which of these two processes is responsible for the existence of a cline is not a trivial problem. Samples from a coastal transect of New Zealand geckos (Woodworthia maculata) identified for the first time a body size cline 7–10 km wide. The larger geckos are almost twice the mass of the small adult geckos. Clines in allele and haplotype frequency were found at two of the four genetic loci examined. Estimated width of the morphological cline was concordant with neither the narrower mtDNA cline (3–7 m) nor the wider nuclear cline (RAG-2; 34–42 km), and cline centers were not coincident. Although the body size cline is narrow compared to the entire range of the species, it is 2–3 orders of magnitude greater than estimates of dispersal distance per generation for these geckos. No evidence of assortative mating, nor of hybrid disadvantage was identified, thus there is little evidence to infer that endogenous selection is maintaining a hybrid zone. We cannot distinguish secondary contact from primary origin of this body size cline but conclude that secondary contact is likely due to the occurrence of mtDNA haplotypes from three distinct clades within the coastal transect and the presence of two frequency clines within this region.

Molecular phylogenetics of the arboreal Australian gecko genus Oedura Gray 1842 (Gekkota: Diplodactylidae): another plesiomorphic grade?

The family Diplodactylidae is the most ecologically diverse and geographically widespread radiation of geckos within Australasia. Herein we present a first comprehensive phylogenetic analysis of relationships of diplodactylid geckos currently assigned to the genus Oedura, a group of relatively generalised arboreal Australian geckos. Maximum Likelihood, bayesian and Maximum Parsimony analyses of a combination of over two and a half kilobases of nuclear (PDC, Rag-1) and mitochondrial (ND2, ND4, tRNA) sequence data all identified four distinctive lineages within Oedura s.l. Based on their deep divergences and a suite of diagnostic morphological characters we recognise each of these four lineages as genera, two of which are monotypic and newly described herein. Our molecular data also suggest that Oedura s.l. is not monophyletic, but is instead a plesiomorphic grade restricted to islands of rocky or forested habitat around coastal and central Australia. In contrast, combined analysis of all data suggests the Australian arid zone is dominated by a single comparatively derived and relatively species rich clade including most other genera of Australian Diplodactylidae. Additional data are required to properly resolve basal divergence events within the Diplodactylidae, however the emerging pattern of relationships and divergence is consistent with the hypothesis that monsoonal and temperate lineages are ancestral to the arid zone fauna, but also indicate that arid zone lineages and radiations are relatively old, and potentially date back to the mid Miocene or earlier.