Biologists still don't understand the mechanisms by which genetic and environmental influences interact to produce well-functioning organisms. This project takes advantage of the wealth of research on stress hormones in the Trinidadian guppy (Poecilia reticulata) to ask how differences in stress hormones coordinate favorable changes in traits influenced by these hormones such as behavior, color, and body size. To address these questions, the project measures hormone levels and various behaviors in fish reared in the laboratory using a breeding design that distinguishes the effects of genetic background and rearing environment. The project will reveal how long- and short-term environmental differences alter hormone levels and the consequences of changes in hormone levels on traits that influence guppy survival. The results will reveal the hormonal mechanisms by which genes and the environment interact to shape multiple traits. In addition, hormone levels - in particular stress hormone levels - are often used to predict health and fitness in wild and domestic animals, and understanding how genetics and environment interact to modify levels in natural populations will improve predictions of how animals respond to novel or changing environments, such as habitat degradation, invasive species, and climate change. This dissertation improvement grant will support the training of a graduate student and research involvement of multiple undergraduate students. The project will also reach out to local middle and high schools using guppies as a model for inquiry-based science in the classroom.
