Meeting Abstract

120.1  Tuesday, Jan. 7 10:30  Tipping the scales: Evolution of the allometric slope independently of average trait size FRANKINO, W. A.*; STILLWELL, R. C.; DWORKIN, I. M.; SHINGLETON, A. W.; University of Houston; University of Houston; Michigan State University; Michigan State University frankino@uh.edu

The scaling of body parts is central to the expression of morphology across body sizes and to the generation of morphological diversity within and among species. Although patterns of scaling relationship evolution have been documented for over one hundred years, little is known regarding how selection acts to alter these patterns. In part, this is because the degree to which the elements of scaling relationships, mean trait size and the slope, can evolve independently is not known. Here, using the wing:body size scaling relationship in Drosophila as an empirical model, we demonstrate that the slope of a morphological scaling relationship can evolve independently of mean trait size. Our success is likely due to in part to our employment of a developmentally-timed diet manipulation to isolate the nutritional static allometry from the genetic static allometry and to our application of selection over many (17) generations. We discuss our findings in the context of how selection likely operates on scaling in nature, the developmental basis of the integration of mean trait size and the scaling relationship slope, and the general approach of using individual-based selection experiments to study the expression and evolution of morphological scaling.