Islands: The ecosystems most vulnerable to biological invasions

Abstract

Islands are ecosystems particularly vulnerable to biological invasions due to their geographic isolation, high specialization and low pressure from natural predators and competition. In fact, invasive species have contributed to 86% of the extinctions of island endemic species. In this research, we review the ecological impacts of biological invasions on islands, both on the functional traits of native species and on different ecological functions and interactions. The introduction of species can affect the functional traits of species, either by increasing functional diversity by adding new traits into the ecosystem, or by reducing it by introducing redundant traits to those of native species. Ecological interactions, both mutualistic (pollination, seed dispersal, plant-microorganism) and antagonistic (herbivory, pathogenic parasitism, predation), can also be altered. The indirect impacts of invasive species, complex and difficult to quantify, can be crucial in island ecosystems, which are commonly affected by multiple invasive species that may interact with each other. Although non-native species can cause significant ecological disruptions, in some cases they can also functionally replace extinct native species. Addressing the knowledge gaps identified in this study will be essential to protect island ecosystems from biological invasions. Future research should adopt interdisciplinary and collaborative approaches that integrate contextual variation and the different levels of ecological organization. Promoting this type of research will be essential to design more effective conservation strategies aimed at preserving not only island biodiversity, but also the stability and functionality of these unique ecosystems.