What is the primary issue caused by non-native species in an ecosystem?

Non-native species often thrive in new environments because they encounter fewer natural predators or competitors. This absence of biological checks allows these species to proliferate unchecked, which can lead to overpopulation. When a non-native species becomes dominant, it can outcompete local species for resources such as food and habitat, disrupting the existing ecological balance. This change typically results in a decline in local biodiversity, as native species may struggle to survive in the face of competition from the non-native invaders. Therefore, the primary issue is that the introduction of non-native species can lead to significant ecological disturbances, primarily due to their unchecked growth and the subsequent impact on the native ecosystem.