Meeting Abstract

1.4  Friday, Jan. 4  From field metabolic rates to genomics, the integrative digestive physiology of snakes SECOR, S.M.; University of Alabama, Tuscaloosa ssecor@biology.as.ua.edu

Snakes feed across a continuum of feeding habits, however little is known regarding the frequency at which snakes feed. Following a 3-year field study on their feeding habits and field metabolic rates, Ken Nagy and I calculated that active foraging coachwhips (Masticophis flagellum) feed on average at 10-day intervals, whereas sit-and-wait foraging sidewinders (Crotalus cerastes) feed at 40-day intervals. These findings sparked the question: might snakes exhibit variation in their digestive physiology given differences in natural fasting durations? Our studies on nearly two dozen species revealed that snakes which feed relatively frequently in the wild narrowly regulate intestinal performance, whereas species which routinely experience long fasting episodes widely regulate intestinal form and function with each meal. The evolutionary rationale for this dichotomous response resides in energy conservation. The mechanistic bases for the two modes of regulation stems from whether intestinal microvilli maintain length with fasting (narrow regulation) or dramatically shorten with fasting and then length with feeding (wide regulation). For infrequently feeding Burmese pythons, the increased expression of more than 2400 genes underlie the rapid postprandial transformation of their intestinal morphology and function. I have had the good fortune to gain from Ken and my other mentors that in order to decipher the evolutionary and proximate mechanisms of adaptation, work needs to start in the field before continuing with approaches in the laboratory that then can transcend multiple levels of design.