Final answer:
Islands are vulnerable to invasions and extinctions primarily due to the introduction of alien species, limited geographic range, and smaller populations of island species.
Step-by-step explanation:
Islands are vulnerable to invasions and extinctions due to several factors. One major factor is the introduction of alien species. Islands have unique ecosystems with endemic species that have evolved in isolation, making them more susceptible to invasive species that disrupt the natural balance and outcompete native species for resources. The limited geographic range and smaller populations of island species also make them more prone to extinction.
Additionally, factors such as habitat loss, climate change, and human activities further contribute to the vulnerability of islands.