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Michael Lynch is a Professor in the School of Life Sciences at Arizona State University and founding director of the Biodesign Center for Mechanisms of Evolution. He received his B.S. in Biology from St. Bonaventure University, and his Ph.D. in Ecology from the University of Minnesota. Dr. Lynch has served as President of the Genetics Society of America, the Society for Molecular Biology and Evolution, the Society for the Study of Evolution, and the American Genetic Association. He is a member of the US National Academy of Sciences, and a fellow of the American Academy of Arts and Sciences. His research is focused on mechanisms of evolution at the gene, genomic, cellular, and phenotypic levels, with special attention being given to the roles of mutation, random genetic drift, and recombination. This work relies on the integration of theory development and computational analysis with empirical work on several model systems, including the microcrustacean Daphnia, the ciliate Paramecium, and numerous microbial species.
Mutation, Drift, And The Origin Of Subcellular Features
Although natural selection may be the most powerful force in the biological world, it is not all powerful. As a consequence, many aspects of evolution of the molecular level can only be explained by the inability of natural selection to operate. This general principle explains a lot about the diversity of genome architectures across species, and also appears to extend to numerous higher-level features of cells: the evolution of the ~1000-fold range in mutation rates that exists among species; greatly elevated rates of transcription error; the divergence of protein architecture; and the restrictions on
the maximum growth capacity of cells.
An emerging fundamental principle underlying all of these observations is that although natural selection relentlessly pushes traits to the highest possible level of refinement, the limits to perfection are dictated by the power of random genetic drift (the role of chance in evolution) rather than by intrinsic molecular limitations. The implications of this drift-barrier hypothesis are that the population- genetic environment (i.e., population size, recombination and mutation rates) imposes a fundamental constraint on the paths that are open vs. closed for evolutionary exploration in various phylogenetic lineages, hence defining the patterns of adaptation seen at the molecular and cellular level.
Genomics Reveals The Mechanisms Of Evolution
Owing to the pronounced technological achievements in genomics and other “omics” fields, a number of new model systems are emerging in biology. In the fields of ecological and evolutionary genomics, foremost among these are: 1) Daphnia pulex, a globally distributed aquatic microcrustacean of interest because of its variation in asexual/sexual mating systems; and 2) Paramecium aurelia, a complex of ciliated protozoan species that emerged after whole- genome duplication 100s of millions of years ago, and yet remain unchanged morphologically.
The focus of the talk will be on the genomic methods that have developed over the past decade, and their applications to these systems. Some of the problems to be discussed include: 1) the use of molecular markers in populations to infer the strength of selection across the genome, to identify key genes associated with major morphological changes, and infer historical changes in population size; 2) the role of gene duplication in the origins of evolutionary novelties and the emergence of new species. Some results from long-term evolution experiments involving the bacterium Escherichia coli will also be discussed.