Our research focuses on the evolution, environmental drivers, and physiological mechanisms of life histories in vertebrates. We answer fundamental questions in aging evolution and ecology using field studies of natural populations, physiological and molecular experimentation, and mathematical modeling. We focus currently on the late-life history, and are primarily interested in the evolution of senescence and lifespan. Our current projects involve dissecting the action of putative aging genes in reptiles, testing for how reptiles escape physiological aging, and modeling senescent rates in mortality and reproduction wild and semi-provisioned primates .
Long-term ecological monitoring of multiple populations of garter snake in the Sierra Nevada mountains have revealed two life-history ecotypes located on the ends of the slow-to-fast pace of life. Fast-paced snakes have fast growth, early maturation, annual and high-effort reproduction, and short lifespan. Slow-pace of life snakes have delayed maturation, infrequent reproduction, and live twice as long as the fast-paced ecotype. These two life history ecotypes result from segregating alleles for growth.
We are asking how immune function (innate and acquired) and cellular stress response (DNA repair efficiency and oxidative stress potential) trade-off with reproduction and survival in these two ecotypes. At the same time, we are researching the endocrinological modulation of these trade-offs by examining the HPA (corticosterone) stress response and how insulin/insulin-like growth factor signaling regulates important life transitions in these organisms.
Summary of differences between slow-living and fast-living garter snake ecotypes around Eagle Lake, CA [pdf]Back to Top
We are broadly interested in dissecting the action and regulation of known longevity genes in reptiles, a group with negligible senescence. Toward this end, we are conducting transcriptome sequencing tests of the evolution of genes involved in metabolic stress and aging. Beginning with the garter snake, we have performed 454 (long read) sequencing of the snake transcriptome for gene discovery and annotation. We have then used RNA-seq (shorter read) transcript sequencing to test for gene expression differences across the transcriptome with an eye toward putative longevity genes and pathways.
Table 1: Preliminary results from sequencingBack to Top
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.Back to Top
In collaboration with many PIs that have long-term censuses of wild primates, we are modeling the rate of actuarial and reproductive senescence in representative species across the primate phylogeny. http://plhdb.nescent.org/Back to Top