Mamíferos exóticos invasores no Brasil: situação atual, riscos potenciais e impactos da invasão de porcos selvagens em florestas tropicais

Abstract

The invasion of exotic species is among the leading causes of biodiversity loss worldwide. Invasive species of vertebrates are recognized as important predators and competitors, and can directly affect native flora and fauna. In addition, some vertebrates are important ecosystem engineers capable of altering physical and chemical characteristics of the environment, resulting in the creation, modification or maintenance of habitats for themselves and other species. Brazil lacks information systematization regarding exotic vertebrate species and their feral populations in the country, not to mention an extreme lack of knowledge of the impact caused by these species. Therefore the present doctoral thesis aims to systematize the information regarding exotic mammals that have established feral and invasive populations in Brazil and assess the impacts of Sus scrofa, one of the invasive vertebrate species with the greatest potential for ecosystem alteration. In the first chapter we present a literature review of exotic mammals that occur in Brazil, their ecological and biological characteristics related to the success of invasion, known impacts and current distribution in Brazil. This chapter also contains a risk invasion analysis of exotic mammal species sold as pets and that still do not occur in the wild in Brazil. All the exotic species that occur in Brazil, as well as the species sold as pets, have a high invasion risk and high potential impact on Brazilian ecosystems. In the second chapter we evaluate the use of streams in Itatiaia National Park by invasive wild pigs (Sus scrofa) and the white-lipped peccary native species (Tayassu peccary). We note that the invasive wild pigs have an ability to alter the physical integrity of streams at a higher intensity than the white-lipped peccary. The streams used by wild pigs present an excavated embankment and sedimented water course, resulting in broader, shallower streams. Finally in the third chapter we present the role of native mammals and invasive wild pigs in the removal of Araucaria angustifolia seed (pine nuts), a species of endangered tree in Brazil. Our results showed that the removal of pine nuts in areas with the presence of wild pigs is high, but that native mammals are the main pine nut removers, with no distinction between small, medium or large mammals or even between wild pigs and native species. We hope the results of this thesis assist in understanding the ecology and impact of exotic mammals in tropical environments, as well as with public policies and control legislation for invasive alien species that aim to reduce their impact on Brazilian ecosystems.