BUNCE, J.A.; EBY, S.L.; O’STEEN, S.: Does c-start performance predict survival of prey encountering predators?

The kinematics of swimming performance are increasingly well studied in fish, but the fitness value, if any, of most kinematic variables remains unknown. This study examines the relationship between classical c-start performance and the locomotor performance and survival of prey during encounters with a predator. The freshwater streams of Trinidad provide a model fauna for studies of predator-prey interactions. We studied the killifish Rivulus hartii, which occurs in two distinct populations in these streams. Populations living downstream of barrier waterfalls are subject to predation from the pike cichlid, Crenicichla alta, while upstream fish appear to live in the absence of a major predator. This laboratory study employs wild-caught Rivulus from both populations to determine (a) if locomotor performance differs between populations and (b) if any component of performance predicts survival. We used high-speed video to first document c-starts of Rivulus in response to a standard stimulus, and second to measure locomotor performance, predator evasion tactics, and time to capture during staged encounters with wild-caught Crenicichla. Preliminary analyses of the staged encounters examined predator approach distance, Rivulus maximum velocity and net distance traveled during the first fast-start response to the predator. These analyses suggest no difference in the performance variables between Rivulus populations. Survival analysis indicates that Rivulus size, but none of the measured performance components influenced time to capture. We will present analyses of the relationship between Rivulus c-start and predator-evasion performance, and compare these results with similar data on guppies, Poecilia reticulata, from the same natural populations.