title: Tipping the scales: Evolution of the allometric slope independent of average trait size.
abstract: 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 well documented for over one hundred years, little is known regarding how selection acts to generate these patterns. In part, this is because it is unclear the extent to which the elements of log-linear scaling relationships-the intercept or mean trait size and the slope-can evolve independently. Here, using the wing-body size scaling relationship in Drosophila melanogaster as an empirical model, we use artificial selection to demonstrate that the slope of a morphological scaling relationship between an organ (the wing) and body size can evolve independently of mean organ or body size. We discuss our findings in the context of how selection likely operates on morphological scaling relationships in nature, the developmental basis for evolved changes in scaling, and the general approach of using individual-based selection experiments to study the expression and evolution of morphological scaling.
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, 77204-5001.|Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland.
authors.forename: R Craig
authors.initials: RC
authors.lastname: Stillwell
authors.affiliation: Department of Biology, Lake Forest College, Lake Forest, Illinois, 60045.|Department of Integrative Biology, Michigan State University, East Lansing, Michigan, 48824.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Shingleton
authors.affiliation: Department of Integrative Biology, Michigan State University, East Lansing, Michigan, 48824.|Department of Biology, McMaster University, Hamilton, Ontario, L9H 6X9, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Dworkin
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, 77204-5001. frankino@uh.edu.
authors.forename: W Anthony
authors.initials: WA
authors.lastname: Frankino
mesh_terms: D000818:Animals; D049628:Body Size / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development; D019143:Evolution, Molecular; D008957:Models, Genetic; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic
keywords: Allometry; constraint; morphological evolution; scaling; selection-artificial