Comparative studies reveal that some characters evolve in a mosaic fashion, whereas others exhibit trends for correlated evolutionary changes. I argue that such evolutionary trends likely reflect the architecture of constraints that various components of an organism impose on each other. Recent advances in developmental genetics have shown that several gene networks and signalling cascades, which operate as relatively context-independent developmental modules, also act as evolutionary building blocks, but the conditions under which developmental modularity promotes the formation of evolutionary building blocks have not been systematically analyzed in theoretical models. Here, I discuss conditions under which developmental modules will tend to act as coherent evolutionary units. I also introduce a theoretical model that promises new insights into the coevolutionary dynamics of multiple traits by simulating the evolutionary fate of multiple genetic loci linked by various degrees of fitness epistasis.
Gerhard Schlosser has been assistant professor at the Brain Research Institute, University of Bremen, since 1999. His research focuses on the development and evolution of neurogenic placodes in frogs. He studied biology at the universities of Freiburg and Ann Arbor, Michigan from 1982 to 1989 (MSc, University of Michigan, with a thesis on “Are Projection-Neurons in the Chick Spinal Cord Arranged in a Segmentally Repetitive Pattern?,” 1987, accepted as diploma thesis, University of Freiburg, 1989). In parallel he studied philosophy at the University of Freiburg from 1984 to 1990, where he obtained his first PhD, summa cum laude, with a thesis on “Die Einheit der Welt und ihre wissenschaftliche Deutung. Wissenschaftstheoretische und systemtheoretische Überlegungen zum Unifikationismus“ (Unity of the world and its scientific explanation. Unificationism from the perspective of philosophy of science and systems theory). From 1991 to 1996, while a research assistant in the laboratory of Prof. Gerhard Roth at the Brain Research Institute, University of Bremen, he pursued his PhD studies in biology (PhD, summa cum laude, with a thesis on “Comparative Studies on the Development of the Peripheral Nervous System in Frogs,” 1995). In 2003 he obtained his Habilitation in Zoology at the University of Bremen (thesis: "Early Development of the Peripheral Nervous System in Amphibians and its Evolutionary Modification“). Dr. Dr. Schlosser has worked at the Centro de Investigaciones en Biologia Celular y Molecular of the Universidad de Costa Rica (1993), and as a postdoc in the laboratory of Prof. R.G. Northcutt at the Scripps Institute of Oceanography and in the Department of Neuroscience of the University of California, San Diego (1996-1998), where he was also involved in a research project on neurogenesis in amphibians in collaboration with Prof. C. Kintner at the Salk Institute. In 1998-1999 he was a Fellow at the Hanse Institute for Advanced Study, Delmenhorst, Germany.