Meeting Abstract

130.3  Tuesday, Jan. 7 14:00  Biogeography and body shape evolution in parallel radiations in the Australian skink genus, Lerista MORINAGA, G*; BERGMANN, P J; Clark University; Clark University gmorinaga@clarku.edu

Squamates are notable for their morphological diversity, exhibiting a variety of body sizes and shapes. Lizards in particular show a wide array of body plans, ranging from lizard-like bodies, exhibiting a tetrapedal and pentadactyl morphology, to snake-like bodies, exhibiting elongate bodies and lacking external limbs. In lizards, the snake-like body plan has independently evolved at least 25 times. This repeated transition from lizard-like to snake-like bodies makes lizards an excellent system in which to study body plan evolution. We focus on the species rich Australian skink genus, Lerista, exhibiting not only lizard-like and snake-like body plans, but also intermediate forms with varying degrees of limb reduction and body elongation. Using a detailed morphometric dataset of 61 species of Lerista, we find that most species fall into two main clades that have undergone parallel radiations in the morphospace. In order to address questions of sympatry between the clades and morphologies, we mapped the geographic ranges of 71 species. We hypothesized that the two main clades would be largely allopatric and for allopatry to occur between morphologically similar species due to competitive exclusion. Finally, we tested for co-evolution between relative body size and relative limb lengths and relative limb element lengths. As expected, relative limb lengths co-evolved with relative body length, and all relative limb elements evolved in a correlated manner with one another, indicating that limbs are reduced as the body is elongated. Furthermore, the rate of change of hind limb elements was different between the two clades, suggesting that Lerista have evolved similar morphologies through different ways.