April 1 2015
12:00 LSB 2320
Cornell Lab or Ornithology, Cornell University
Why kin selection is not dead: Evidence from a marginal cooperative breeder
Cooperative breeding refers to any case in which more than just two individuals tend a single nest or brood. While its relatively rare in the animal kingdom, it represents an evolutionary paradox, because individuals appear to be sacrificing personal reproduction for the good of the group. In the 1960s inclusive fitness theory and Hamiltons rule provided a novel framework for understanding why individuals might sacrifice personal reproduction to come to the aid of close kin, an explanation that was recently challenged by modeling efforts and lackluster attention to empirical evidence. Western bluebirds offer an unusual opportunity to explore the role of inclusive fitness in facultative decision-making within a fluid system where individuals are plastic in terms of whether they remain near kin and whether they breed independently or become helpers. This presentation brings together evidence from a long-term study to explore the role of kinship and inclusive fitness benefits in a suite of decisions that lead to breeding near kin and occasionally helping at nests of close relatives. A combination of experiments and demographic data provide a good case for the importance of kinship, resources, and limitations on breeding, and highlight how settling in close proximity to kin provides opportunities for facultative helping in the event of failure to get a mate. Our results provide a perspective on local settlement that does not require ecological constraints, which are ubiquitous, while also pointing to interesting possibilities for how sexual selection and kin selection can interact, favoring helping through both current and delayed fitness benefits.