Meeting Abstract

15.2  Thursday, Jan. 3  Developmental mechanisms of plasticity: cellular response to muscle function in skeletal traits YOUNG, R; University of Arizona rlyoung@email.arizona.edu

Selection for local adaptation, especially to widely fluctuating environments, often favors greater sensitivity of development to environmental inputs. This sensitivity or plasticity in trait development is often noted across environments; however, the developmental mechanisms that enable incorporation of such inputs are not well understood. In skeletal traits, muscle stimulation throughout ontogeny can modify patterns of gene expression regulating rates of cell division and differentiation and thus may be critical for mediating developmental response to environmental inputs. Here, we examine the importance of muscle function for growth and differentiation in soricid shrew mandibles (Sorex monticolus). In shrews, skeletal growth is known to be highly sensitive to environmental conditions and previous studies indicate that mandible morphology is highly correlated with mandible musculature, making Sorex shrews an especially suitable system to examine developmental mechanisms of plasticity. We assess cellular response to muscle function by comparing bone microstructure across individuals experiencing different muscle loading regimes and examine the contribution of this response to variation in morphology and bite force. We discuss the implications of these results for the evolution of adaptive plasticity and morphological diversification in skeletal traits.