Introduced mammals in the Neotropics and the genetic paradox of invasions

Abstract

The information on the number of mammalian species introduced and established into the Neotropical Region and the knowledge on their history of introduction and ecological-genetic aspects are rather variable. To improve our understanding on these topics, we provide an updated list of mammalian species that have established wild populations in the Neotropics and, where possible, compare genetic variability between native and introduced populations in order to evaluate whether the genetic paradox of invasions (GPI) applies to these species. Our search exposed an evident lack of genetic data for most populations introduced in the Neotropics, which restricted our analysis to 10 out of the 51 mammalian species introduced and to only three neutral molecular markers. Losses of genetic variability were a frequent feature of introduced populations, suggesting that these populations have overcome low genetic variation and successfully established in the new environment adding support to the conditions needed to be considered paradoxical in the sense of the GPI. However, it was not possible to affirm that the magnitude of the loss is related to the number of introduction events or the number of individuals introduced or translocated. Alternative approaches to obtain better estimates of genetic diversity associated with the evolutionary potential of the species at the initial stages of invasion are needed. They will provide valuable insight into ecological and evolutionary processes involved in biological invasions, and useful information for species-based risk assessment of invasion.