Determinants of introduction success in alien mammals

Despite intensive research on colonization by non-native species, ecologists still cannot accurately predict their invasive abilities and likely ecosystem impacts. This study was set out to analyze the determinants of the success of mammal introductions. We applied several types of phylogenetic linear and logistic multiple regression methods. Determinants of success were divided into external (introduction-specific) factors, principally introduction effort (measured as the number of introductions per species), and the proportion of introductions to islands/mainland; and intrinsic (species-specific) factors, including life history (litter size, body mass), ecological (diet breadth, activity breadth, trophic level), biogeographical (latitudinal range), and neuro-behavioral (brain size and sociality) traits. We found that the main determinants of introduction success are introduction-specific factors (i.e., introduction effort and island/mainland proportion) and not those of the species itself. A species' neuro-cognitive traits are the exception, and these probably play a key role in the ability of founder individuals to recognize and utilize the resources available in novel environments and thus survive the bottleneck imposed by low initial population numbers.