Meeting Abstract
Though many teleosts appear to be fully aquatic and show no obvious morphological adaptation to life on land, they are still able to produce a tail-flip jump to move effectively across terrestrial environments. This study examined killifishes in the order Cyprinodontiformes, which display a gamut of jumping behaviors, from those which can propel themselves up to eleven body lengths in a single jump to those that struggle to become airborne. We hypothesized that, as killifishes spend more time on land, selection pressures should drive the evolution of a morphology better suited for terrestrial locomotion and that species-level variation in fish size and shape is associated with different jumping abilities. Based on results from previous comparative studies, we predicted that species with shorter, deeper bodies would generate less effective jumps (i.e., producing less displacement), relative to fish with larger longer, shallower bodies. We filmed ten individuals (600fps) from three species of killifish that vary widely in their morphology: Gambusia affinis ( “good” jumper), Jordanella floridae (intermediate jumper) and Poecillia mexicana (“poor” jumper). While that there was no clear effect of body shape, we found that smaller, lighter species jumped further (when distance is calculated in body lengths), relative to larger, heavier species. In addition, the time it took to complete the jumping behavior was negatively correlated with how far a fish could jump; that is, faster fish fly farther. We predict that amphibious fish species will evolve smaller body sizes and rapid behaviors to facilitate moving about on land.
