Meeting Abstract

P3-75   -   Morphological evolution of limbs as a function of habitat use; a comparative analysis in Sceloporus lizards Ronnebaum, AC*; Rivera, JA; Fuentes-G, JA; Martins, EP; Arizona State University; Arizona State University; University of Alabama; Arizona State University aronneba@asu.edu

Although shorter limbs may offer arboreal animals more stability while climbing, animals that live in complex habitats may balance competing selective pressures by varying the relative lengths of different limb segments. The genus Sceloporus boasts a diverse group of lizards that vary tremendously in morphology and ecology with over 100 described species. Taxa can be found from beaches to high elevation alpine forests and vary in size from 39.67mm to 125.15mm snout-to-vent length. Moreover, some species possess sexual size dimorphism while other species show little difference in size between the sexes. With recent advancements in imaging technology, we can gain new and detailed information about skeletal morphology and how it relates to habitat use. Here, we use CT imaging and phylogenetic comparative analyses to compare limb morphology of terrestrial and arboreal species to determine if habitat preference has resulted in differences in limb length. Additionally, we test whether this relationship is the same among males and females. We found that habitat use relates to forelimb length for both sexes such that arboreal species have longer forelimbs. Importantly, the overall difference is driven by the humerus, radius, and digit length in females but in males the difference in forelimb length is only driven by the humerus and the digit. We found no difference in hindlimb lengths between arboreal and terrestrial species. Our results suggest that speed and efficiency on broad tree trunks may be an important selective pressure on arboreal lizards that counteract the benefits of shorter limbs when on narrow twigs. We discuss also differences in the evolution of limb segments and between the sexes.