Biology Department Colloquium with Dr. Daniel Bolnick '96

“Why genetic variation persists within populations, and why we should care”
Natural selection tends to remove less-fit genotypes from populations, because they survive or reproduce at a lower rate. Consequently, we expect that selection will gradually eliminate variation within populations, leading to a monoculture of genetically identical individuals. But this does not actually happen: variation persists within most natural populations. Is this variation neutral, persisting only because it is functionally irrelevant and does not affect fitness? Or, might natural selection actually promote diversity? I argue that natural selection often favors diversity for its own sake: there can be benefits to being different from everyone else in a population. Drawing on ecology, immunology, animal behavior, and evolutionary genetics, I will present a set of studies illustrating some of the reasons why genetic variation persists, and why this variation has practical consequences that we should care about.

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