RESEARCH IN HONG KONG

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MUTATION RATES IN LARGE AND SMALL POPULATIONS

MSc Chaowei (Charlene) Zhang

Mutations are the ultimate source of genetic variation, but with the exception of few model species, we still know little about de novo mutation rates in the wild, how much intraspecific variation there is in mutation rates, and what ultimately determines large difference in mutation rates among different species and populations. The drift-barrier hypothesis posits that the species effective population size is an important determinant of mutation rate: since most mutations are harmful and selected against, and because selection is more efficient in large than in small populations, drift in small populations renders them prone to increased mutation rates. However, since estimation of mutation rates is challenging, very little is known about intraspecific variability in mutation rates, and tests of the drift-barrier hypothesis at intraspecific level are missing. Our aim is to obtain accurate estimates de novo mutation rates from multiple stickleback populations differing dramatically in the amount genetic drift they have experienced and test if there is a negative relationship between mutation rate and effective population size as predicted by the drift-barrier hypothesis.