Research

Field site: Eagle Lake, California

Thamnophis elegans (western terrestrial garter snake)

Color polymorphism in Thamnophis elegans

Comparative evolution and ecology of senescence in reptile populations

Populations of garter snakes in the Sierra Nevada mountain range have two genetically determined growth phenotypes coinciding with lakeshore and meadow habitats. Fast growth animals (found in lakeshore populations) have early reproduction and short lifespans (5 years) while slow growth animals (in mountain meadow sites) have late reproduction and are long lived (ca. 15 years). We believe the key ecological difference between the two habitats is the near absence of predators in meadow sites, resulting in a low-hazard selective environment.

Current research explores the differences in predation rates, population dynamics and age-specific mortality and fecundity rates between these garter snake populations. This research also investigates the physiological mechanisms behind the extended lifespans of the slow growth phenotypes (such as differential rates of cellular oxidative damage). Much of this work is in collaboration with Dr. Stevan J. Arnold at Oregon State University.

semi-natural population of baboons

Biodemographic indices of reproductive senescence in baboons

As part of a large collaborative project, lead by Dr. Marc Tatar and the Southwest Foundation for Biomedical Research, we are developing the baboon as a model for studying human aging. Our work focuses on the biodemographic indices of reproductive senescence. Specifically, our reproductive aging project involves hormonal profiling of aging female baboons and their longitudinal decline in fecundability, ending ultimately in the menopause.