Prof. Steven N. Evans

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It is a challenge to explain biological phenomena that appear to arise from the complex
interaction of many genes in response to natural selection acting through the mechanisms of
mutation and recombination. The proportions of a large population that have various
genotypes form a probability measure on the space of possible genotypes and, under suitable
assumptions, it is reasonable to model this probability measure as evolving in time according
to a relativelysimple, continuous-time, measure-valued dynamical system. I will explore the
structure of this dynamical system and its equilibria with a view to shedding light on
evolutionary explanations of the similar patterns of senescence and mortality seen in many
multi-cellular organisms. In particular, I will point out how the non-linear nature of the
dynamical system causes problems with a popular explanation of the Gompertz-Makeham
mortality curve and requires a reformulation of Haldane's Principle, one of the cornerstones of
the theory of mutation accumulation. This is joint work with David Steinsaltz (Oxford)
and Kenneth W. Wachter (Berkeley).

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University of California at Berkeley
Lecture Hall, Cologne Biocenter
Contact: not specified