Meeting Abstract
Snake-like body shapes have evolved convergently many times in all major clades of vertebrates. Although these species superficially look similar, it is unknown whether they have arrived at this convergent body shape through similar patterns of evolution of their body parts. Several clades of lizards have evolved snake-like body shapes and have multiple intermediate phenotypes between short-bodies with pentadactyl limbs and elongate bodies without limbs. The pathways of body part evolution were studied here for seven such clades of lizards: Bachia, Brachymeles, Chalcides, Hemiergis, two clades of Lerista, and Scelotes. Patterns of digit gain and loss, the integration of body parts, the occurrence of threshold relationships between body parts, and phylomorphospace occupation were compared among these clades to test whether they evolved their body parts following convergent pathways. On the one hand, clades had similar patterns of digit gain and loss evolution and integration of body parts. On the other hand, different clades had different pairs of traits related by threshold-like versus gradual relationships. Results from the phylomorphospace gave a complex picture of body shape evolution, but suggested that most clades evolved differently. These findings showed that although all seven clades have evolved similar snake-like body shapes, the evolutionary pathways that they followed to arrive at these body shapes differ, suggesting a lack of constraint in how body shapes can evolve.
