Global determinants of prey naivete to exotic predators

Prey naivete-the failure of prey to recognize novel predators as threats-is thought to exacerbate the impact that exotic predators exert on prey populations. Prey naivete varies under the influence of eco-evolutionary mediating factors, such as biogeographic isolation and prey adaptation, although an overall quantification of their influence is lacking. We conducted a global meta-analysis to test the effects of several hypothesized mediating factors on the expression of prey naivete. Prey were overall naive towards exotic predators in marine and freshwater systems but not in terrestrial systems. Prey naivete was most pronounced towards exotic predators that did not have native congeneric relatives in the recipient community. Time since introduction was relevant, as prey naivete declined with the number of generations since introduction; on average, around 200 generations may be required to erode naivete sufficiently for prey to display antipredator behaviour towards exotic predators. Given that exotic predators are a major cause of extinction, the global predictors and trends of prey naivete presented here can inform efforts to meet conservation targets.