Research in the Ketterson Lab

Research interests: Physiological and behavioral ecology, phenotypic integration, hormones and behavior, adaptation and constraint, avian biology, animal migrations, animal behavior, sex and gender

     

Main Research Interests

Natural selection shapes organisms as integrated sets of traits, but it is unclear how easily these sets of traits can be assembled and disassembled in response to selection. Hormones often underlie the co-expression of traits, and these hormonal correlations may promote adaptation in some contexts, but may delay evolutionary response in others. Therefore, by understanding the ways in which hormones mediate phenotypes, we can better understand the evolution of life histories, sexual dimorphism, and population divergence.

Phenotypic integration and independence can be studied via experimental manipulations of hormonal phenotypes, assessment of patterns of natural variation in hormones in relation to phenotype and fitness, comparisons of hormonal phenotypes across populations, and mechanistic studies of hormones and their interaction with target tissues. The research conducted in the Ketterson lab currently employs all these approaches by focusing on testosterone and its effects on the phenotype of males and females of a songbird, the dark-eyed junco.

Junco Research in the Field

Research in the Ketterson lab happens both in the lab and in the field, studying populations of juncos all over North America. Click to learn more about our field research sites!

     

Specific Research Projects

Some of the ongoing research projects in the Ketterson lab include:

Examining the evolution of hormone-mediated suites of traits by asking whether the relationships between testosterone and various phenotypic traits are consistent or different across populations facing different selective pressures. See Christy Bergeon Burns's and Jonathan Atwell's pages for more details.

Using a long-term data set on junco reproduction and paternity to understand how engaging in multiple mating affects the fitness of males, females, and their offspring, as well as to determine what traits underlie the variation in which individuals are likely to engage in extra-pair mating, and what forces shape the observed patterns of extra-pair mating over time. See Nicole Gerlach's page for more details.

Using molecular and neuroendocrine techniques, we are beginning to understand how an individual's ability to process T may predict T-mediated phenotypes. For example, are males and female similarly sensitive to T and its metabolites in brain nuclei that regulate reproductive and social behaviors? At the neural level, do the sexes use similar mechanisms to achieve outwardly similar phenotypes? Using quantitative real-time PCR and immunocytochemistry, we are investigating the functional consequences of individual variation and sex differences in neural sensitivity to T. For more information, see Kim Rosvall's page.

Investigating how variation in endocrine production and response mechanisms, such as the HPG axis or neural steroid sensitivity, may relate to hormone-phenotype relationships across divergent subspecies. See Christy Bergeon Burns's page for more details.

Using the junco as a model for understanding how sexual dimorphism develops, both in individual lifespans, by measuring hormones during development and in adulthood and seeing how they relate to behavior and morphology; as well as in evolutionary time scales, by examining how selection acts on females that are more/less similar to males. See Kristal Cain's page for more information.

Determining the function of high amplitude, long-range song (LRS) and low amplitude, short-range song (SRS) in inter- and intrasexual interactions, and relating among-subspecies variation in LRS and SRS to reproductive isolation and speciation within the genus Junco. See Dustin Reichard's page for more information.

Using a recently completed large scale sequencing project to develop microarrays to analyze changes in gene expression in the junco. Following years of effort and data collection to understand the effects that testosterone has on physiology and behavior, we are now able to asses what changes are occurring "under-the-hood." Understanding these changes will allow a greater understanding of the way multiple organ systems interact in response to changes in testosterone in response to social challenges or seasonal shifts. See Mark Peterson's page for more details.