Meeting Abstract
Salamanders undergo a highly derived developmental cycle that requires a transition from an aquatic to a land environment, accomplished by considerable musculoskeletal and locomotor changes. Indeed, their movement capability appears to be limited to gaits up to a moderate speed, lumbering trot. Previous studies show strong metamorphic and locomotor changes linked to the transition from swimming to walking in taxa with aquatic larvae (Ambystoma). However, locomotor performance shifts in more terrestrial, direct-developing salamanders such as Spanish populations of the fire salamander (Salamandra salamandra) have not been characterized. In this study, we aimed to determine: 1) the changes in (fully viviparous) fire salamander morphology through ontogeny and 2) how these changes relate to changes in locomotor mechanics. We hypothesized that, like Ambystoma, there would be an ontogenetic transition in locomotor performance that occurs early in ontogeny and is linked to changes in limb and/or body morphology. To test our hypothesis, anthropomorphic data (e.g., body and limb length) were collected from 164 salamanders of varying age (weight range: 0.13-21.91g). High speed video data were collected using 3 GoPro cameras during five gait trials per individual. Gait variables were calculated from ~1300 strides and used to construct linear mixed effects models for statistical analysis. Mass was found to significantly influence maximum speed (p=0.02) and stride frequency (p<0.001), with smaller (i.e., younger) salamanders exhibiting higher stride frequencies and salamanders of intermediate size exhibiting the fastest speeds. These results also have bearing on early tetrapod motion as salamanders are the commonly used postural model.
