The elaborate and diverse visual displays of animals have inspired biologists and challenged our understanding of evolution for centuries. Many colorful displays are costly to produce, making them reliable signals of an individual's quality to mates and rivals. In this signaling system, the perception of color is essential; however, relatively little is known about the costs of and constraints on the performance of the visual system. Yellow, orange, and red carotenoid pigments are the basis of the colorful displays of many bird species, including the house finch (Carpodacus mexicanus), and carotenoid coloration is affected by an individual's health and dietary access to these pigments. Interestingly, carotenoids also accumulate in the avian eye where they filter light, protect the eye, and tune color vision. Therefore, carotenoid pigments may provide a unique biochemical link between the production and perception of colorful visual displays.
The investigators will use dietary manipulations, biochemical analyses, and behavioral experiments to investigate how carotenoid accumulation in the eye affects color-based foraging and mate selection of house finches. They will change carotenoid levels in the eye by feeding the birds diets with high and low levels of carotenoid pigments and then compare the foraging and mate choice for colorful plumage in a series of behavioral experiments.
These studies provide a new direction for the study of signal and sensory system evolution. Results will be published in scientific and layperson (e.g. magazines and public presentations) forums to foster scientific learning among broader audiences. These studies will provide opportunities for undergraduate, minority, and youth scholars within the institution and community to participate in laboratory analyses and behavioral experiments.
