Meeting Abstract

60.3  Wednesday, Jan. 6  Pelvic Sexual Dimorphism in the Carnivora: A Phylogenetic Approach SCHUTZ, H*; KRIEGER, J.D.; GURALNICK, R.P.; GARLAND, T. Jr.; Univ. of California, Riverside; The Natural History Museum; Univ. of Colorado, Boulder; Univ. of California, Riverside heidisc@ucr.edu

In many mammalian groups, the pelves of females are differently shaped and are relatively and absolutely larger than those of males, regardless of dimorphism in body size. This pattern of dimorphism is the opposite of that found in body size and craniodental features. Thus, pelvic dimorphism is potentially driven by evolutionary processes different than those affecting body size and other structures. The pelvis serves three biomechanical roles in mammals: weight-bearing, reproduction, and locomotion. Weight-bearing affects pelvic shape due to the stress that body mass places on the limbs. Reproduction affects pelvic shape by requiring an ample aperture for the passage of offspring, and the relationship between maternal size or maternal pelvic geometry and offspring size have been linked to indicators of female pelvic size and shape. Locomotion affects pelvic shape through requirements for limb orientation and muscle attachment, and pelvic shape varies considerably with locomotor mode, even within the same species where locomotor differences can be very subtle. This study employed a comparative phylogenetic approach to examine variation in the magnitude of pelvic size and shape dimorphism in relation to the independent variables of mating system, relative offspring size, and locomotor mode. Pelvic shape and size dimorphism varied with all variables in a complex mosaic of interactions. Mating system had a greater effect on size than on shape dimorphism, and locomotor mode had an effect on both size and shape dimorphism. Of the two offspring size ratios, the ratio of offspring mass to female pelvic size had a different effect on shape and size dimorphism than the ratio of offspring mass to female mass.