Convergent morphological evolution in Squamata: developmental modularity and body elongation patterns

Abstract

Evolution of snakelike morphology, characterized simultaneously by body elongation and limb reduction, has occurred several times along evolutionary history of Squamata. Ecomorphological studies suggests that the multiple origins of snakelike morphologies in squamates has frequently occurred in association with the occupation of different habitats, resulting in two distinct ecomorphs: epigeous species, which generally have elongated trunk and tail, and fossorial species, which generally have elongated trunk and short tail. The elongation of these body regions (trunk and tail) could be given by an increase of vertebrae number or lenght. However, there are no broad studies investigating how body elongation has occured in snakelike ecomorphs of Squamata, neither studies on the developmental basis associated with trunk and tail as independent developmental modules in squamate species. The aims of the present research project are: to investigate if trunk and tail constitute independent developmental modules in different lineages of Squamata (except Serpentes), to characterize the main developmental genes associated with body axis regionalization in species of a lizard family (Gymnophthalmidae) that present elongated morphologies and finally, to observe the effects of overexpression of these genes in diferentiation of body axis regions (trunk and tail) during embrionic development of Reptilia. (AU)