Meeting Abstract
P3.177 Sunday, Jan. 6 Corticosterone regulates the transition from courtship to feeding behavior in male red-sided garter snakes (Thamnophis sirtalis). LUTTERSCHMIDT, DI; Portland State University, Oregon d.lutterschmidt@pdx.edu
Seasonal modulation of glucocorticoids plays an important role in supporting critical life-history events such as reproduction and migration. In a well-studied population of red-sided garter snakes (Thamnophis sirtalis parietalis), glucocorticoids are elevated during the brief mating season. Glucocorticoids likely facilitate energetically expensive courtship behavior, as snakes do not eat during the mating season and must migrate up to 17 km to forage at feeding grounds. Our previous data demonstrated that dispersing male red-sided garter snakes have significantly lower baseline corticosterone than courting males, suggesting that elevated corticosterone is necessary to support reproductive behavior. To test this hypothesis, I collected 40 courting male snakes and randomly assigned them to one of two implant treatments: control or 5 mg metyrapone, a corticosterone synthesis inhibitor. Snakes were housed in outdoor arenas and blood samples were collected 0, 2, 4, and 7 days post- treatment. Males were then tested on a y-maze and allowed to choose between a female or worm trail (i.e., a courtship or feeding cue). As expected, plasma corticosterone decreased significantly during the mating season (P < 0.001). A significant interaction between treatment and sampling time occurred (P = 0.024), indicating that the seasonal decline in corticosterone depended on treatment condition. Significantly more snakes receiving metyrapone (16 of 20) chose worm trails than snakes receiving the control implant (6 of 20; P = 0.004). These results indicate that a decrease in plasma corticosterone induces the behavioral switch from reproduction to foraging during the spring mating season. Future studies are needed to understand the mechanisms by which corticosterone regulates this seasonal transition in behavior.
