Meeting Abstract
Investment in current versus future reproduction is a prominent trade-off in life-history theory, and is likely dependent on an individual’s life expectancy. The terminal investment hypothesis posits that a reduction in residual reproductive value (i.e. potential for future offspring production) will result in increased investment in current reproduction. We tested the hypothesis that male decorated crickets (Gryllodes sigillatus), when cued to their impending mortality, increase investment in current reproduction by shifting the composition of their nuptial food gifts, or spermatophylaxes, in a way that increases their gustatory appeal to females. Using a repeated measures design, we analyzed the amino acid composition of spermatophylaxes derived from males both before and after injection of either a saline control or an immune challenge solution of heat-killed gram-negative bacteria, the latter of which, although non-pathogenic, may signal an impending threat to the survival of the cricket. The gustatory appeal of spermatophylaxes was assessed by mapping their composition on a fitness surface derived in an earlier study that identified female preference for amino acid composition of nuptial food gifts. We found that immune-challenged males maintained the level of attractiveness post-treatment, while control males produced significantly less attractive gifts post-injection. These results are consistent with the hypothesis that cues of a survival threatening infection stimulate terminal investment in male decorated crickets with respect to the quality of their nuptial food gifts.
