Meeting Abstract

12.3  Sunday, Jan. 4  The evolution of developmental patterns in the Anolis skeleton SANGER, TJ*; MAHLER, DL; LOSOS, JB; ABZHANOV, A; Harvard Univeristy tsanger@oeb.harvard.edu

One of the major challenges in modern biology is elucidating both the ultimate and proximate mechanisms of adaptive phenotypic evolution. Caribbean Anolis lizards exhibit numerous morphological specializations that are well understood in their ecological and phylogenetic contexts, making them an ideal group to examine the developmental and molecular mechanisms that underlie morphological divergence. We have begun a series of studies to more thoroughly assess skeletal variation among Anolis habitat specialists and examine its developmental bases. We are primarily interested in studying variation in cranial and limb proportions among the trunk-crown and trunk-ground habitat specialists. Trunk-ground anoles, which live primarily on broad substrates, have relatively long limbs and a short snout compared the trunk-crown anoles living higher in the canopy on narrower perches. A preliminary phylogentic reconstruction of Anolis skull evolution indicates that the face and cranium have evolved independently suggestive of developmental modularity, but also potentially indicating a complex selective history. An allometric analysis of the developing skeleton for eight species indicates that the facial region of the skull and long bones diverge at the earliest stages of morphogenesis further indicating that a change in skeletal patterning may have occurred during the divergence of these habitat specialists. Variation in skull depth and width appears to have a more complex pattern of allometric growth. Using A. carolinensis and A. sagrei as model species we have also begun examining the expression patterns of several candidate genes known to be involved in skeletal development. To conclude we summarize these expression patterns and discuss their potential roles in the divergence of anole morphology.