Meeting Abstract

P1.15  Saturday, Jan. 4 15:30  Male green treefrogs use acoustic signals to manipulate the stress physiology of receivers LEARY, C.J.; Univ. of Mississippi cjleary@olemiss.edu

Agonistic interactions among male anurans characteristically involve the exchange of acoustic signals. Detection of nearby conspecific males, for instance, often results in the production of advertisement calls that are directed at the encroaching individual and may escalate to include the production of distinct aggressive calls. I examined how acoustic signals influence corticosterone (CORT) and androgen levels in male green treefrogs, Hyla cinerea. Males in natural choruses that were recently involved in an aggressive acoustic interaction had significantly higher levels of CORT than males that were not involved in an aggressive interaction. Additionally, while winners of aggressive bouts and non-aggressive males had similar circulating androgen levels, losers of aggressive bouts had significantly higher CORT levels and lower androgen levels. I subsequently simulated territorial intrusions by broadcasting isolated aggressive calls or advertisement calls to captive males to examine the effects on hormone levels in signal receivers. Males exposed to aggressive calls exhibited a dramatic increase in CORT level and a reduction in androgen level. Surprisingly, males exposed to isolated advertisement calls showed a similar hormonal response but aggressive calls were more effective at eliciting elevations in CORT. CORT level is inversely related to androgen level and high CORT/low androgens negatively affect the attractiveness of vocal signals or suppress vocalization in this species. Hence, signaling males may increase their chances of acquiring mates by eliciting elevations in CORT level in rival males. Results will be compared to previous work in anurans that showed a stimulatory effect of advertisement calls on androgen production in signal receivers.