Meeting Abstract

88.6  Friday, Jan. 7  Sex differences in the effect of environmental cues on reproductive development in pine siskins WATTS, H.E.*; SIMENHOFF, C.L.; HAHN, T.P.; Loyola Marymount University; Univ. of California, Davis; Univ. of California,Davis; Univ. of California, Davis hwatts1@lmu.edu

To ensure that reproduction only occurs when success is likely, organisms have evolved to use environmental cues to regulate the reproductive axis appropriately. Although much research has examined changes in reproductive physiology in response to proximate environmental cues, relatively little is known about the extent to which males and females differ in their responses. Here, we compare the use of food and social cues by male and female pine siskins (Carduelis pinus) to time the onset of reproduction. We experimentally manipulated food type and the presence of a potential mate as birds transitioned from non-breeding to breeding condition, in order to assess effects on reproductive physiology in each sex. Both males and females were responsive to food type during the initiation of reproductive development. Access to preferred food types (seeds) enhanced initial gonadal development in both sexes. In contrast, females but not males, were responsive to the presence of a mate during completion of reproductive development. Interestingly, the effects of a mate on female reproductive development appear to be modulated by the degree of affiliation of the pair. The observed sex difference in responsiveness to social cues may relate to differential reproductive investment by males and females.