Meeting Abstract
Animals that provide parental care to their offspring often face behavioural and immunological trade-offs. Hormones have been implicated in mediating these trade-offs, with androgens often promoting aggressive behaviours at the expense of both reduced nurturing behaviour and immunity. Conversely, prolactin can promote nurturing behaviour and immunity but may reduce aggressive behaviours. We tested the effects of these hormones on parental care and immunity in bluegill sunfish, a species in which males build nests and provide sole parental care to the offspring. Immediately after spawning, parental males received one of five hormone manipulations: (1) placebo; (2) 11-ketotestosterone (11-KT); (3) flutamide, an androgen receptor antagonist; (4) prolactin; or (5) bromocriptine, a prolactin-release inhibitor. We then recorded the frequency of nurturing and aggressive parental care behaviours and measured their immune response to exposure to Vibrio. We found that prolactin-treated males exhibited significantly more nurturing behaviours, whereas 11-KT-treated males exhibited more aggressive behaviours relative to the other treatments. Within hormone treatments, there was no apparent effect of the immune challenge on these behaviours. We discuss the hormone-mediated trade-offs during parental care and the immune response in the parental males.
