The ability of Drosophila hybrids to locate food declines with parental divergence

Hybrids are generally less fit than their parental species, and the mechanisms underlying their fitness reductions can manifest through different traits. For example, hybrids can have physiological, behavioral, or ecological defects, and these defects can generate reproductive isolation between their parental species. However, the rate that mechanisms of postzygotic isolation other than hybrid sterility and inviability evolve has remained largely uninvestigated, despite isolated studies showing that behavioral defects in hybrids are not only possible but might be widespread. Here, we study a fundamental animal behavior—the ability of individuals to find food—and test the rate at which it breaks down in hybrids. We measured the ability of hybrids from 94 pairs of Drosophila species to find food and show that this ability decreases with increasing genetic divergence between the parental species and that male hybrids are more strongly (and negatively) affected than females. Our findings quantify the rate that hybrid dysfunction evolves across the diverse radiation of Drosophila and highlights the need for future investigations of the genetic and neurological mechanisms that affect a hybrid’s ability to find a suitable substrate on which to feed and breed.