May 11 2011

12:00 LSB 2320

Michael A. Bell
Department of Ecology and Evolution, SUNY, Stony Brook

Vertical Integration of Evolutionary Mechanisms: Pelvic Reduction in the Threespine Stickleback Vertical Integration of Evolutionary Mechanisms: Pelvic Reduction in the Threespine Stickleback


More than 3.5 billion years of evolutionary history has produced existing biological diversity. The traits that form this diversity reflect mechanisms that act simultaneously at several levels of causation and can influence each other. The causal levels range from DNA sequences, genetic architecture, gene expression, and developmental genetic networks to ecological interactions involving individuals, populations, and metapopulation systems. Since mechanisms at one level of causation influence mechanisms at higher and lower levels, evolutionary biology must develop model systems in which “vertical integration” of evolutionary mechanisms – up and down the chain of causation – plus the consequences of those mechanisms for evolutionary history can be studied. While we have very good models to study mechanisms at one or a few adjacent levels of causation and other systems in which evolution has been observed over long geological periods, few model organisms can be studied at all levels of causation and observed over extended periods. Thus, we know little about mechanistic interactions across multiple causal levels and their consequences for evolutionary history. It is feasible to study evolution of pelvic girdle reduction in the threespine stickleback fish (Gasterosteus aculeatus) at every level of causation and to integrate knowledge of these mechanisms with genetic and phenotypic properties of extant and fossil lineages. The power of vertical integration of evolutionary mechanisms is apparent from its ability to explain otherwise inexplicable patterns of genetic and phenotypic variation in pelvic reduction of the threespine stickleback. The ability now to study whole genomes of previously non-model species has made vertical integration of evolutionary mechanisms from DNA sequences to modern populations and fossil lineages feasible, but its importance in evolutionary biology is underappreciated.











































































































































































































































































































































































































































































































































































































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