Little evidence for morphological change in a resilient endemic species following the introduction of a novel predator

Human activities, such as species introductions, are dramatically and rapidly altering natural ecological processes, and often result in novel selection regimes. To date, we still have a limited understanding of the extent to which such anthropogenic selection may be driving contemporary phenotypic change in natural populations. Here we test whether the introduction of the piscivorous Nile perch, Lates niloticus, into East Africa's Lake Victoria and nearby lakes coincided with morphological change in one resilient native prey species, the cyprinid fish Rastrineobola argentea. Drawing on prior eco-morphological research, we predicted that this novel predator would select for increased allocation to the caudal region in R. argentea to enhance burst-swimming performance, and hence escape ability. To test this prediction, we compared body morphology of R. argentea across space (nine Ugandan lakes differing in Nile perch invasion history) and through time (before and after establishment of N...