Bruce Lyon (PI) and Daizaburo Shizuka Proposal #:IOS-0808579 Cognitive constraints on adaptation: chick recognition as host defense against conspecific brood parasites
Parents typically preferentially care for their own offspring over the offspring of others when they can tell them apart. Some birds, that are commonly called brood parasites, exploit parental care by laying their eggs in the nests of others. An outstanding question is why victims of this type of reproductive parasitism provide care for the offspring of other individuals or even of other species, particularly when the offspring vary dramatically from their own. This recognition failure is especially surprising considering that hosts of brood parasites have often evolved the ability to recognize and reject brood parasite eggs that look much like their own. In this study, Shizuka and Lyon develop a theoretical model to show how a constraint in the general process of learning to recognize offspring may explain why brood parasitic offspring are accepted in some species, but not others. The experimental portion of the study will then address whether this model can apply to American coots (Fulica americana), a waterbird. Female coots lay eggs in each other's nests, and many of these parasitic eggs hatch along with the host's eggs. Preliminary data suggests that some parent coots recognize parasitic chicks and treat them differently from their own. The experiments will determine (a) whether coots can recognize and discriminate between host and foreign chicks, (b) what general type of learning mechanism is used to develop recognition, and (c) whether chick vocalizations are the cues used in recognition. By integrating a theoretical model with experimental manipulations of cognition, this study will contribute to a greater understanding of how the mechanisms organisms use to solve ecological problems can constrain adaptive evolution. The project will train undergraduate students in field research and molecular methods, and the findings will be incorporated into an Ecology Talk program for local K-12 students.
