HANNA, Jandy; Duke Univ., Durham, NC: Vertical climbing energetics in prosimian primates

As a primarily arboreal radiation, all non-human primates must climb in order to feed, escape predators, and sleep. However, some primates such as apes, spider monkeys, and lorises have morphological and behavioral specializations (i.e. long limbs and long strides) that may enhance efficiency during vertical climbing. This project represents the first test of the relationship between locomotor (and morphological) patterns and metabolic cost during vertical climbing. Loris tardigradus is a prosimian primate with several morphological characteristics related to climbing, while Cheirogaleus medius is a generalized prosimian primate with no reported traits for climbing. Initially, I collected videorecords of these species during climbing on a rigid support and found that L. tardigradus uses larger joint excursions and longer step lengths than C. medius. Then, I used a variable speed rope-treadmill and a Sable^� gas analysis system to measure oxygen consumption during steady-state climbing. Experiments were videotaped to determine step length during flexible support climbing, as well. Subjects climbed the treadmill for 20 to 30 minutes at a constant speed, while oxygen content of the air was recorded. Additionally, resting metabolic rate was determined for each subject in order to provide a measure of the relative increase in active metabolic cost. Results suggest that the specialized climber, L. tardigradus, uses less energy to climb at a given speed than C. medius. These data, in combination with step length data, suggest that, like various other locomotor modes, climbing is �priced by the step,� (Alexander & Ker, 1990; Kram & Taylor, 1990). Thus, primates with morphological and behavioral traits related to long step lengths may have an energetic advantage during climbing. (Supported by an NSFGRF, a Sigma Xi GIAR, and an Aleane Webb institutional DIG)