The Genetic Architecture of Adaptation in Laboratory Yeast Populations

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0075594ZeylThe genetics of adaptation will be studied in laboratory yeast populations to test current theories of how populations respond genetically to selection. Every 24 hours, approximately 2 million cells from each population will be transferred to a tube of fresh medium. As the cells reproduce, random mutations that improve growth and survival in this environment will spread, changing the genetic makeup of the population. Each population undergoes about 2400 generations per year, allowing a substantial amount of genetic change to be observed. Samples of each population will be frozen every 100 generations, allowing both the degree of adaptation and the genes of each population to be compared directly to those of its ancestor.The adaptations that fit organisms to their environments are a central feature of biology, but in most organisms adaptation cannot be observed in action or studied in genetic detail. Some fundamental questions therefore remain unanswered. For example, does adaptation typically involve few mutations with major effects, or many mutations each with a slight effect? Is adaptation a reproducible process, or does the randomness of mutation make every response to selection unique? In this project the process of adaptation will be observed directly, as it occurs. The powerful techniques of yeast genetics will then provide new insight into how the genes match an organism to its environment.