Meeting Abstract
Morphological scaling is central to the expression and evolution of morphology. Scaling relationships fit to populations of individuals describe how overall shape changes with body size, and changes in scaling relationship parameters underlie the generation of much morphological diversity seen within and among biological groups. We take a developmental approach to model the expression and evolution of morphological scaling. Under our model, final trait and body size is a function of their relative sensitivity to changes in access to nutrition during well-defined growth windows. Because individual growth is dependent on access to nutrition, each individual can express a continuum of trait and body sizes. The function that describes these potential trait and body sizes is, in effect, a ‘cryptic’ scaling relationship on which the observed phenotype exists as a single point. Importantly, individuals can vary in their sensitivity to nutritional variation, producing differences among individuals in the intercept and slope of their individual cryptic scaling relationships. Our model reveals that the distribution of these individual cryptic scaling relationships can dramatically affect how the population-level scaling relationship responds to selection. Here we present data illustrating individual cryptic scaling relationships from several biological systems, and we use these data to explore our model’s predictions of the response to different patterns of selection.
