Abstract # 18:

Scheduled for Thursday, June 17, 2010 11:00 AM-11:10 AM: Session 5 (Medallion Ballroom B) Oral Presentation


CAUSES AND CONSEQUENCES OF HYPOMUSCULARITY IN PRIMATES

M. N. Muchlinski1, J. J. Snodgrass2 and C. J. Terranova3
1Marshall University, Department of Anatomy, 1542 Spring Valley Drive, Huntington, West Virginia 25701, USA, 2University of Oregon, Eugene, 3Mt. Sinai School of Medicine
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Variation in basal metabolic rate (BMR) is strongly correlated with variation in muscle mass in mammals, and both of these variables are correlated with latitude and ambient temperature. It is hypothesized that selection alters BMR in response to thermoregulatory pressures, and that selection uses muscle mass as a means to generate this variation. Primates are hypomuscular compared to most other mammals. Primates are a tropically adapted order, thus the previously proposed hypothesis that hypomuscularity may be a result of thermoregulatory pressures can be partially supported. However, there is a considerable amount of variation in muscle mass within primates. Using new muscle mass data we present a possible ecological explanation for residual variation in muscle mass in primates. Muscle mass data were collected from the African, Asian, and Malagasy strepsirrhines, and from the haplorrhine, Tarsius syrichta. We combined these new muscle mass values with an extensive literature-based sample of metatherians and eutherians. Results of our study show that muscle mass scales isometrically with body mass and that primates are hypomuscular when compared to most other mammals [t(1, 77)=-5.04; P<0.001]. Among primates, substrate preference, activity pattern, and BMR could not explain residual variation in muscle mass. However, our results find dietary differences can [t(1, 22)=-1.28; P<0.001] explain differences in muscle mass; where frugivores are hypermuscular, while insectivores and folivores are hypomuscular.