Meeting Abstract

P3.56  Saturday, Jan. 5  Age-specific patterns of morphological integration in Verreaux’s sifaka LAWLER, R.R.*; WUNDERLICH, R.E.; Boston University; James Madison University rlawler@bu.edu

Morphological traits that serve a common function or are specified by a common developmental pathway are expected to evolve tight patterns of integration via genetic and phenotypic covariances. The theory of morphological integration is explicitly developmental in that integrated traits come to be coselected or coinherited due to correlational selection acting on two or more traits during ontogeny. At present, few studies have examined how patterns of morphological integration change across ontogeny. In this study, we compare patterns of morphological integration across three age classes using data collected from a wild population of sifakas (Propithecus verreauxi verreauxi) inhabiting a protected reserve in southwest Madagascar. We examine the covariance structure among seven linear measurements (lengths of humerus, radius, hand, femur, tibia, foot, and tail) in 90+ animals from each age class. We represent patterns of integration as conditional independence graphs and use information theoretic statistics in order to analyze the patterns of integration among the three age classes. We find that yearlings have a qualitatively different pattern of morphological integration from juveniles and adults. Compared to the other two age classes, yearlings retain more statistical associations among traits. This implies that in the first year of life postcranial growth is more tightly regulated during the period when yearlings are developing locomotor coordination. Adults, however, demonstrate fewer but stronger functional associations between elements. These age-specific patterns of integration point to which traits likely experience strong correlational selection during sifaka ontogeny.