INTERACTIONS OF BEHAVIOR AND PHYSIOLOGY DURING THE ANNUAL REPRODUCTIVE CYCLE OF THE RED-SIDED GARTER SNAKE (THAMNOPHIS SIRTALIS PARIETALIS)

Abstract

Canadian populations of the red-sided garter snake (Thamnophis sirtalis parietalis) have a severely limited yearly period-for growth and reproduction. Breeding occurs immediately on emergence from winter dormancy, before annual gonadal recrudescence occurs. Because this temporal dissociation of gonadal function and reproductive behavior is unlike that occurring in other vertebrates, T. sirtalis presents an array of related questions concerning the role that physiology plays in controlling reproductive behavior. Attractivity of females is the result of a pheromone produced in the liver and related chemically to vitellogenin, a precursor of yolk. This pheromone communicates potential fecundity. Male sexual activity requires a period of winter dormancy, and sexual behavior appears to be independent of the presence of the testes and pituitary. Sexual receptivity of females is effected by environmental temperature.