Meeting Abstract
59.4 Wednesday, Jan. 6 To breed or not to breed: stress and reproductive decision-making in Galapagos marine iguanas VITOUSEK, Maren N.*; MITCHELL, Mark A.; ROMERO, L. Michael; AWERMAN, Jessica; WIKELSKI, Martin; University of Colorado, Boulder; University of Illinois at Urbana-Champaign; Tufts University; Tufts University; Max Planck Institute for Ornithology and Princeton University maren.vitousek@colorado.edu
It is unusual for seasonal breeders to frequently skip opportunities for reproduction. We investigated the relationship between physiological state and reproductive decision-making in Galápagos marine iguanas (Amblyrhynchus cristatus), a species in which females typically reproduce biennially, although the proportion of breeding individuals varies significantly across years. Nearly all adult-sized females initiated follicular development prior to the lekking period, but 38% of females resorbed all developing follicles 5-15 days before the start of copulations. Receptive and non-receptive females differed in reproductive hormones during the mate choice period. Testosterone peaked in receptive females immediately prior to copulation. Non-receptive females showed significant peaks in both testosterone and progesterone during follicular atresia. Both baseline and stress-induced corticosterone levels were significantly lower in receptive females two to three weeks prior to the period of reproductive decision-making (and the onset of follicular atresia in non-receptive females). Females that continued to develop follicles were also in higher body condition and initially produced larger follicles. Reproduction is extremely costly in this long-lived species, and increases the likelihood of mortality in the year following breeding; females could therefore gain significant benefits from being attuned to indicators of reproductive success. We suggest that corticosterone may modulate reproductive decisions by altering individual sensitivity to both internal and external cues of the likelihood of successful reproduction.
