Species Specificity of Sex Pheromone Trails of Sympatric and Allopatric Garter Snakes (Thamnophis)

Abstract

Male garter snakes of the sympatric species T. butleri and T. sirtalis were tested in a Y-maze apparatus for their ability to discriminate female pheromone trails. Both species significantly chose arms containing conspecific females'' trails in tests in which the other arm contained either no pheromone trail or a pheromone trail from a female of the other species. The male T. butleri were also tested for ability to discriminate between trails of conspecific females and trails of females of the closely related but allopatric T. radix. No preference occurred, so apparently species specificity of these trail pheromones has not evolved.