Meeting Abstract
Sexual selection theory posits that animals should fiercely compete to reproduce, but in taxa that breed cooperatively, some individuals delay or even forgo reproduction entirely. Though kin selection often is evoked to explain the evolution of this reproductive strategy, other extrinsic factors likely contribute to the maintenance of fitness asymmetries. In many polytocous taxa, siblings constrain each other’s reproductive opportunities. The intensity and form of sibling competition, though, may well depend on the sex of the competitors. Using longitudinal records, we investigated how intra- and intersexual competition among siblings impacts body condition, survivorship, and reproduction in a cooperatively breeding primate – the golden lion tamarin (Leontopithecus rosalia). Our preliminary results suggest that sibling sex influences some, but not all, phenotypic outcomes in golden lion tamarins. Ultimately, this examination of sex-dependent sibling competition provides insight into the mechanisms mediating phenotypic outcomes as well as the demographic factors selecting for cooperative breeding across broad taxonomic and geographic scales.
