During her doctoral research, Emily Durkin, Ph.D., experimentally evolved a population of facultatively parasitic mites, Macrocheles muscaedomesticae (shown here attached to Drosophila hydei flies) to exhibit an increased propensity in host-attachment behavior using artificial selection. Her research was the first to provide an estimate of heritability for infectious behavior in a facultative parasite, suggesting natural selection can act upon facultative strategies.