Meeting Abstract

S11.4  Friday, Jan. 7  The evolution of the vestibular system and controlled aerial descent in non-specialized arboreal squamates HERREL, A*; BOISTEL, R; LOSOS, J; VANHOOYDONCK, B; MNHN/CNRS; Universite de Poitiers; Harvard University; University of Antwep anthony.herrel@mnhn.fr

Controlled aerial descent has evolved at least 30 times independently in different vertebrate and invertebrate lineages. A whole suite of morphological modifications, such as patagia, lateral skin folds and webbed feet have been suggested to enhance descending ability. Yet, among squamates several at first sight unspecialized species are capable of some form of controlled aerial descent. Here, we provide new data on the capacity to perform a controlled aerial descent in a relatively unspecialized Iguanid lizard (Anolis pentaprion). Our data show that A. pentaprion has few morphological specializations but rather uses existing structures to increase its surface area during a controlled descent. These behavioral adjustments allow this species to change its orientation during the descent and reduce terminal velocity upon impact. In addition, we use synchrotron based microtomography to quantitatively compare the structure of the semi-circular canals in six squamates that have independently evolved the ability to perform a controlled aerial descent (Holaspis guentheri, Anolis pentaprion, Draco volans, Ptychozoon kuhlii, Leiolepis belliana and Chrysopelea ornata) and compare it to the inner ear structure of closely related terrestrial species. Our data suggest that inner ear structure shows strong phylogenetic signal, and the inner ear of squamates capable of performing controlled aerial descent appears relatively unspecialized. Finally, our data suggest that the initial steps in the evolution towards controlled aerial descent are likely associated with behavioral rather than morphological specializations.