Meeting Abstract
Understanding how selective forces influence patterns of symmetry remains an active area of research in evolutionary biology. One hypothesis, which has received relatively little attention, suggests that the functional importance of morphological characters may influence patterns of symmetry. Specifically, it posits that features with greater functional importance should be more symmetric. The aim of this study was to examine the patterns of fluctuating asymmetry (FA) present in the limb bones of freshwater turtles (family Emydidae). Aquatic emydid turtles of the subfamily Deirochelyinae employ a hindlimb-dominant swimming style, suggesting that hindlimbs should display lower levels of FA. In contrast, some emydids are more terrestrial (subfamily Emydinae). As terrestrial locomotion places more equal importance on fore- and hindlimbs, such behaviors may minimize differences in FA. This dichotomy in propulsive modes provides an excellent test of the morpho-functional hypothesis of symmetry. Consistent with the hypothesis, we found a strong, clade-wise pattern of higher forelimb FA in aquatic species (Deirochelyinae). This pattern was not detected in the more terrestrial subfamily Emydinae, although it is possible that factors other than ecology impact may impact this. We also detected a phylogenetic signal in FA within the femur and discovered that FA has evolved at vastly different rates between the fore- and hindlimbs.
