Amat Orriols, F.

Strange geckos in a strange land: did morphological evolution and climatic diversification lead to ecological radiation and speciation in Flap-footed Lizards (Pygopodidae) during the Miocene aridification of Australia? pp. 51-62 plus Supplementary documents.

Abstract. Pygopodids are more than forty species of gekkonoid lizards with an elongated body, no forelimbs and rudimentary hindlimbs that are reduced to flap appendices, endemic to Australasia. I explored the process of morphological evolution and diversification of pygopodids from a biogeographic and ecological perspective, subjecting body size and shape to comparative methods along a phylogenetic tree of species. In particular, I analysed the tempo of morphological diversification and disparification of Flap-footed Lizards in relation to the aridification of Australia and the arrival of Asian reptile faunae to the continent, and whether it is related to its ecological radiation and speciation. The transition from an ancestor with a short body and four limbs to the final elongated and partially limbless body plan of Pygopodidae occurred before the Miocene aridification of Australia. However, the current morphological diversification of Flap-footed Lizards is concordant with the opening of new habitats and the spread of the new squamate fauna that arrived from Asia during the Miocene aridification of Australia. Pygopodid lizards diversified in body shape and size from an ancestral terrestrial form with tail that was longer than the body, leading to different morphologies that do not fully agree with previous categorisations of the species’ ecologies. The evolution of body size in Flap-footed Lizards experienced an initial strong phenotypic rate that led to large disparity and was followed by a decline during the rest of its evolutionary history. Hence, the evolution of body size and the colonization of warm regions of Australia are positively associated with speciation whereas the diversity of body shapes could be linked with ecological divergences, thus suggesting that pygopodids deserve further investigation to test whether they must be considered an example of adaptive radiation.

Key words. Squamata, Gekkota, adaptive radiation, ecomorphology, speciation.