Condition-dependent Signal Reception: Limitations and Functions of Carotenoids in Avian Color Vision

Project: Research project

Description

Animal signals like brilliant colors communicate reliable information about individual quality to signal receivers (e.g. potential mates) because they are expensive to produce or maintain. However, few studies have considered whether signal reception by receivers is also differentially costly, which would have profound implications for the evolution of animal signaling systems. I propose to study the costs and behavioral significance of a signal reception mechanism in a communication system where the same molecules may underlie the production and reception of the signal. Flashy red carotenoid colors in birds are classic examples of sexually selected quality signals, because color production is dependent upon dietary intake and health actions of limited carotenoid pigments. Carotenoids, however, are also present in the avian eye, where they may play key roles in photoprotection, light absorption, and ultimately how the visual system is tuned to seeing color. Thus, I hypothesize that carotenoid accumulation in the eye is a condition-dependent trait (like carotenoid coloration) that controls the extent to which individuals can visually discriminate carotenoid-based color variation. To test these hypotheses, I will dovetail biochemical, physiological, nutritional, and behavioral approaches in ecological and experimental studies of an abundant songbird (the house finch, Carpodacus mexicanus) that is a model species for studies of sexual selection and carotenoid coloration. id=SP

Description

I am writing to request REU supplement funding for my current NSF grant Conditiondependent signal reception: limitations and functions of carotenoids in avian color vision (IOS-0923694). This research project examines the control and value of carotenoid pigments in the eyes of house finches (Carpodacus mexicanus) across the urban, suburban, and rural desert landscapes of Phoenix, Arizona. This REU supplement will fund an undergraduate student who will be working directly with myself (Kevin McGraw) conducting population genetic analyses of blood samples that we have obtained from a large field survey of finches. We have found notable microgeographic variation in visually mediated foraging behavior (i.e. food color preferences) in our studies of urban, suburban, and rural house finches, such that birds from populations with redder males (e.g. rural/desert sites) have a feeding preference for redder foods. While we are also testing environmental and physiological mechanisms underlying this observation, we are now anxious to perform genetic analyses of finches using microsatellites to determine if birds from urban, suburban, and rural sites are genetically distinct, which would have major implications for sexual selection and the evolution of mating preferences, feeding preferences, and male coloration. The student will be strongly encouraged to use our data on genetic differentiation and variation, gene flow, and effective population size to develop an independent research project during the summer. The REU supplement will provide an exciting and intellectually stimulating research experience for an undergraduate, and will contribute to our understanding of color vision and production as well as urban impacts on animals

Description

I am writing to request REU supplement funding for my current NSF grant Conditiondependent signal reception: limitations and functions of carotenoids in avian color vision (IOS-0923694). This research project examines the control and value of carotenoid pigments in the eyes of house finches (Haemorhous mexicanus) across the urban, suburban, and rural desert landscapes of Phoenix, Arizona. This REU supplement will fund an undergraduate student who will be working directly with myself (Kevin McGraw) conducting antioxidant, oxidative stress, and immunological analyses of tissue samples that we have obtained from a large field survey of finches. We have found notable microgeographic variation in visually mediated foraging behavior (i.e. food color preferences) in our studies of urban, suburban, and rural house finches, such that birds from populations with redder males (e.g. rural/desert sites) have a feeding preference for redder foods. While we are also testing environmental mechanisms underlying this observation, we are now anxious to perform physiological analyses of finches to determine how birds from urban, suburban, and rural sites may differ in their internal uses of carotenoids (e.g. as antioxidants, immunostimulants). The student will be strongly encouraged to use our previously gathered data on coloration, vision, and behavior to develop an independent research project during the summer. The REU supplement will provide an exciting and intellectually stimulating research experience for an undergraduate, and will contribute to our understanding of color vision and production as well as urban impacts on animals.

Description

I am writing to request REU supplement funding for my current NSF grant Conditiondependent signal reception: limitations and functions of carotenoids in avian color vision (IOS-0923694). This research project examines the control and value of carotenoid pigments in the eyes of house finches (Carpodacus mexicanus), both in our primary urban study site and in surrounding suburban and rural desert environments. This REU supplement will fund an undergraduate student who will be working directly with myself (Kevin McGraw) on a key lab experiment that will occur during the molt period (July-August). Specifically, this research will determine (1) how carotenoid access and oxidative stress affect carotenoid accumulation and coloration during molt, and (2) how urban and rural birds differ in carotenoid uptake and expression patterns under controlled conditions. We will accomplish these goals by experimentally manipulating dietary carotenoid amounts and oxidative stress in captivity during the molt period and assessing feather color, antioxidant and health state, and retinal carotenoids. The student will be strongly encouraged to develop and conduct an independent research project during the summer. The REU supplement will provide an exciting and intellectually stimulating research experience for an undergraduate, and will contribute to our understanding of color production and vision as well as urban impacts on animals.
StatusFinished
Effective start/end date8/15/097/31/13

Funding

  • NSF: Directorate for Biological Sciences (BIO): $324,000.00

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color vision
carotenoids
color
research projects
college students
deserts
birds
feeding preferences
pigments
funding
molting
students
oxidative stress
animals
antioxidants
sexual selection
summer
foods
eyes
Carpodacus mexicanus