Dr. John D. Hatle Assistant Professor B.A. Luther College, 1991 Ph.D. University of Louisiana – Lafayette, 1998 Post-doc Illinois State University, 1998-2003 Joined UNF faculty in 2003 Email: jhatle@unf.edu Homepage

I am interested in the physiological abilities of animals to respond to the environment, and the limits on these responses. I study how insects make clutches of eggs and age as a way of addressing this basic question in biology. The lubber grasshopper (Romalea microptera) is used for these studies.We have described phenotypic plasticity in egg production and identified developmental phases in which egg production does not respond to changes in diet. Lubber grasshoppers need to attain a threshold of protein storage to initiate reproductive development. After attaining the threshold, the reproductive tactics of an individual female becomes increasingly unresponsive to changes in food availability, first fixing age at laying and later fixing number of egg to be laid. In these studies, we track egg-yolk protein (vitellogenin) or the hormone that stimulates the production of egg-yolk protein (juvenile hormone) throughout development. We intend to compare they physiology underlying plasticity due to diet vs. photoperiod, because we hypothesize that these environmental manipulations produce plasticity in fundamentally different ways. We also plan to test the ability of juvenile hormone manipulations to commit grasshoppers to the fixed phase of egg production.

I also study aging in insects. Calorie restriction (i.e., eating only ~70% of the calories of a normal diet) extends lifespan in many organisms, including female lubber grasshoppers. We have shown that reducing calories after middle-age (60% of the way through adult life) enhances longevity in female grasshoppers. We are now beginning to address the roles of heat shock proteins and insulin-like molecules in aging.