Predator-Mediated Selection on Burst Swimming Performance in Tadpoles of the Pacific Tree Frog, Pseudacris regilla

Abstract

Two experimental approaches were used to determine if burst swimming speed in Pseudacris regilla tadpoles is subject to selection by predatory garter snakes, Thamnophis sirtalis. In eight out of 10 experiments in seminatural arenas, fast tadpoles survived snake predation more often than expected (P < 0.01). In videotaped encounters, tadpoles that escaped attacks swam 1.68 times as fast (P < 0.0001) and nearly four times as evasively (P < 0. 05) as those that were captured. Burst swimming speed is clearly important to success at escaping snakes in experimental arenas and, given widespread snake predation on tadpoles, is probably subject to predator-mediated selection in nature.