Meeting Abstract

P1.108  Sunday, Jan. 4  THE PHYSIOLOGICAL CONSEQUENCE OF MALARIA INFECTION IN THE WESTERN FENCE LIZARD, SCELOPORUS OCCIDENTALIS. SCHOLNICK, D. A.*; MANIVANH, R. V.; SAVENKOVA, O. D.; Pacific University, Oregon; Pacific Unversity, Oregon david.scholnick@pacificu.edu

We examined the influence of reduced hemoglobin concentrations resulting from malaria infection on thermoregulation and metabolism in the Western fence lizard, Sceloporus occidentalis. Malaria infections diminish the oxygen carrying capacity of the blood, depressing hemoglobin concentrations by as much as 25% in lizards. Western fence lizards collected from central and southern Oregon were screened for Plasmodium mexicanum. Malaria infected and uninfected lizards were placed in a temperature controlled treadmill at preferred body temperature (34.5^oC) and induced to walk at constant speed for 5 minutes (0.7 m min^-1) or sprint maximally to exhaustion (< 2 min of activity). Malaria infection significantly increased preferred body temperature in a thermal gradient following sustained activity (2 to 4^oC increase; ANOVA P < 0.05) but had little impact on thermoregulation following exhaustive exercise. There was a strong negative correlation between hemoglobin concentration and post-activity body temperature but no indication of post-exercise anapyrexia typically reported in oxygen limited lizards. Excess oxygen consumption during recovery was about 40% higher in infected lizards when compared to uninfected after similar levels of activity. Malaria infection significantly elevated blood lactate following sprint or endurance activity (20 and 36% elevation, respectively) when compared to uninfected lizards. Our findings suggest that there are additional metabolic costs, measured as excess oxygen consumption and thermoregulation disruptions associated with malaria induced hemoglobin depression. These results may help explain limited size and reproductive success previously measured in malaria infected lizards.