Meeting Abstract

P2.130  Tuesday, Jan. 5  Associated reproduction in a model dissociated breeder, the red-sided garter snake PARKER, M. ROCKWELL*; FRIESEN, CHRIS R.; MASON, ROBERT T.; Oregon State Univ., Corvallis parkermi@science.oregonstate.edu

Most vertebrates exhibit an associated reproductive pattern, where maximal sex steroid production, mating behavior, and gametogenesis occur simultaneously or at least in close proximity. The other pattern, dissociated reproduction, is typified by the uncoupling of one of the aforementioned components from the others. The red-sided garter snake (Thamnophis sirtalis parietalis) has long been described as a model dissociated breeder. Maximal courtship and mating in this species occur in the spring of every year following winter dormancy while sex steroid levels are basal (or at least decreasing) and no gametogenesis is occurring. Following the spring mating season, all snakes disperse from the den to various lakes and ponds of the Interlake Region of Manitoba, Canada, where they will undergo gametogenesis and/or vitellogenesis and parturition with a concomitant increase in sex steroid synthesis. Over the past two summers, we have surveyed male snakes for courtship behavior at a specific summer site (Fish Lake) and found that ~50% of the males exhibit courtship behavior (chin rubbing and body alignment). We bled all of the males to measure their total androgen levels via radioimmunoassay. Males that exhibit courtship behavior in the summer have higher total androgen levels than non-courting males, suggesting that androgens may be directly activating courtship behavior during the summer feeding period concomitant with gametogenesis. Though the intensity of late summer mating behavior pales to that induced by prolonged low temperature dormancy, this species may be unique in that it exhibits both associated and dissociated reproductive patterns.