Selection on escape performance in natural populations of guppies.

Alistair J. Cullum and Albert F. Bennett
Department of Ecology and Evolutionary Biology
321 Steinhaus
University of California, Irvine
Irvine, CA 92697-2525

American Zoologist, 36(5): 60A (1996)

Presented at:
1996 Annual Meeting of the Society for Integrative and Comparative Biology
Albuquerque, New Mexico

Abstract. — The rapid or "C" start is a reflexive escape response in fish that is believed to be important in avoiding predation. We therefore anticipate selection for improved rapid start performance in fish populations exposed to high levels of predation. Contrary to this expectation, in previously reported work we found no evidence for genetic differences in rapid start performance in guppy (Poecilia reticulata) populations from high versus low predation sites. It is possible however that selection on performance occurs in wild populations experiencing high predation frequency, but that phenotypic differences are not heritable and thus do not result in any genetic changes. To investigate this possibility, we collected fish from high and low predation sites in multiple Trinidadian streams and videotaped rapid starts initiated by a standardized stimulus. The rapid starts were digitized to yield data on angular velocity, linear velocity, and distance moved in 24ms. Preliminary results on one pair of high and low predation populations suggest that some aspects of performance differ in these wild-caught populations. Supported by NSF Grant IBN-9420155.