Meeting Abstract
Gecko toe pads have been investigated for over 200 years, and interest in them has burgeoned since the turn of the millennium. Geckos are very diverse (~1700 species). About 60% of species have toe pads comprised of a hierarchy of morphological specializations involved in effecting adhesion and release. Toe pads are complex adaptations and their evolutionary history remains contentious. Since the 1950s arguments advanced advocating either a single or multiple origins of toe pads have been hampered by the poor resolution of gekkotan interrelationships. Employment of recently-constructed (from 2012 onward) robust, molecularly-based phylogenies of the Gekkota has failed to resolve the question of one or more origins of the adhesive system, largely because toe pads have been assessed as a single attribute, with scant attention being paid to their anatomical diversity. To attempt to rectify this we examine 34 features of gecko digits and investigate each using model-based ancestral state reconstruction. In this initial approach we undertake a pan-gekkotan overview to determine what, if any, broad-scale patterns exist. We find few characters common to all pad-bearing geckos, with particular features instead characterizing more restrictive clades, consistent with multiple origins of toe pads. We recognize that more refined studies within families will be needed to elucidate finer details of pattern. Exploration of this issue is important not only for understanding the evolution of the adhesive apparatus of geckos (and for what that can tell us about the evolution of complex adaptations), but also for gaining greater insights into which of its features are essential to model in biomimetic applications of its functional attributes.
