Conservation and variation in the agonistic repertoire of the brook stickleback, Culaea inconstans (Kirtland)

Abstract

Interpopulation variability in behaviour is thought to play a role in the production of bio- logical diversity on this planet. The brook stickle- back, Culaea inconstans, is a prime candidate for investigations of such variability because mtDNA sequences indicate that it diverged into two distinct lineages 3.6-4.8 mya; more than enough time for differences to evolve. In this paper we show that, despite long periods of allopatry, the brook stickle- back's agonistic repertoire has remained quite conser- vative. Existing variability represents shifts in the mean population frequencies (performance parameter) of some displays, rather than changes in the compo- sition of the agonistic repertoire itself (presence or absence of behavioural elements).