Meeting Abstract
P2.10 Wednesday, Jan. 5 Sex ratio influences courtship behavior in the butterfly Bicyclus anynana DRUCKER, C.B.; WESTERMAN, E.L.*; MONTEIRO, A.; Yale University; Yale University; Yale University erica.westerman@yale.edu
Successfully identifying, attracting, and keeping a mate is one of the most important tasks an individual completes in life; and has led to sexual selection for a wide variety of mating behaviors. One factor driving mate behavior and consequent male-female interactions and intra-sexual interactions is the operational sex ratio (OSR). However, the degree to which OSR influences mating behavior through altering male-female interactions and intra-sexual competitive interactions simultaneously is rarely studied. We therefore explored the effects of OSR on inter- and intra-sexual interactions in the butterfly Bicyclus anynana. We manipulated OSR by setting up cages, each with three individuals, where half the cages contained one male and two females (OSR of 1:2) and the other half contained two males and one female (OSR of 2:1), and monitored the activity of all individuals. We predicted that male-female interactions would be plastic in response to OSR and increase with increased male-bias, unless mate competition played a greater role in determining mating outcome. We found male courtship of females to be significantly greater in the female-biased than the male-biased treatment, and the activity level of the two males to be highly correlated within trials in the male-biased treatment. No behavior varied between treatments for females. Our results suggest that male-female interactions are plastic in response to OSR, but this plasticity is essentially driven by changes in male-male interactions that play a predominant role. These findings indicate that the addition of intra-sexual competition is sufficient to decrease inter-sexual interactions, that this behavioral plasticity in response to changes in OSR may be sex-specific, and that both mate attractiveness and mate competition are important components of mate selection in B. anynana.
