Multivariate phenotypic evolution in developmental hyperspace

Complex phenotypes are constructed during development by interactions among an intricate array of factors including genes, gene products, developmental units, and environmental influences. Although patterns of genetic variation and covariation play a clear role in determining patterns of phenotypic evolution (Lande 1979), it can be difficult to understand how various patterns of developmental interactions affect the evolutionary process, due to the complexity of developmental systems. However, recent advances in theory (e.g., Cowley and Atchley 1992; Atchley et al. 1994; Rice 1998, 2002; Gilchrist and Nijhout 2001; Wolf et al. 2001), and an explosion of interest in evolution and development, make it clear that a consideration of developmental interactions provides major insights into character evolution, including the evolution of phenomena such as canalization (Rice 1998), phenotypic integration (Cheverud 1996; Rice 2000), and genetic variance-covariance structure (Atchley 1984; Atchley and Hall 1991; Atchley et al. 1994; Atchley and Zhu 1997). These insights might allow one to predict (Rice 2002) or reconstruct (Lande 1979; Schluter 1996) evolutionary trajectories, and to identify the proximate basis of differentiation within or among species (e.g., Stem 1998; Kopp et al. 2000; Sucena and Stern 2000).