Meeting Abstract

80.4  Friday, Jan. 6  Are all snakes made equal: handling hypoxic conditions. CAMPBELL, JC*; COBB , VA; Middle Tennessee State University

Fossorial animals are generally exposed to different environmental conditions than their terrestrial counterparts. Because of enclosed surroundings with little air space and reduced air flow, hypoxic and hypercapnic conditions (LO2/HCO2) would be expected, and animals that frequent such environments could exhibit physiological adaptations (e.g., reduced metabolic rates). As the early evolutionary history of snakes likely involved fossorial conditions but extant species exhibit great diversity in habitat selection and lifestyle, we hypothesized corresponding respiratory metabolic variation. We addressed this question by using closed-system respirometry to measure oxygen consumption on two fossorial and two terrestrial snake species under normal and simulated LO2/HCO2 environments at three temperatures(15, 25, 30 °C). Basal metabolic rate (BMR) was calculated by placing individuals in a respirometry chamber and measuring VO2 every hour for 24 hours using normoxic air; hypoxic/hypercapnic simulations were performed by flowing air from pre-filled gas tanks(15% O2 and 5% CO2) through the respirometry setup and measuring VO2 every hour for 12 hours. At normoxic conditions, the terrestrial species had higher BMRs than the fossorial species, particularly at the warmer temperature treatments. At LO2/HCO2 conditions, BMRs remained similar to normoxic conditions for the fossorial species, but there was a rapid increase in BMR for the terrestrial species associated with the highest temperature treatment. We suggest fossorial snakes may exhibit reduced metabolic rates as well as mechanisms to handle LO2/HCO2 conditions and that their more terrestrial species may have lost. Understanding such physiological variation may help strengthen the evolutionary lineages of snakes as well as provide insights into the plasticity of physiological systems.