The role of malaria parasites in invasion biology

Abstract

Invasive organisms are non-indigenous species that are introduced outside its natural range, where they expand and establish. These non-indigenous species colonize new habitats and undergo rapid proliferation, imposing severe ecological and health impacts on invaded ecosystems. However, not all the translocated species beyond their native range become successful invaders and, hence, particular features may allow some alien species to establish and spread in the new geographical range. Some evolutionary hypotheses have proposed that pathogens may play an important role in this context, explaining the invasion success of their hosts. Since bird species harbor a wide variety of malaria and related haemosporidian parasites, the bird-malaria interaction represents an ideal model to test these evolutionary hypotheses. The Enemy Release Hypothesis proposes that invasive species are more competitive in newly colonized habitats because they left behind their natural parasites in their original geographic range. Alternatively, the Novel Weapon Hypothesis builds on the idea that parasites are co-transported by the invasive species into newly colonized habitats, and these parasites can act as biological weapons if they infect and harm native competitors. Conversely, the Biotic Resistance Hypothesis claims that parasites from native community may reduce the fitness of potential invasive species and hence prevent their colonization in the new environments. In this chapter we will review the main scientific contributions showing the role of avian malaria parasites in the global spread of their bird hosts, assessing the features of both bird hosts and malaria parasites to become a fruitful invader. We will also highlight the extinctions and endangerment of numerous native species provoked by avian malaria invasions globally.