Final answer:
Invasive species can drastically modify ecosystems, outcompete or prey on native species, introduce diseases, and potentially lead to native species' extinction, resulting in ecological imbalance and biodiversity loss.
Step-by-step explanation:
Invasive species can cause harm to their environment by various means, including ecosystem modification, out-competing native species, and introducing new parasites and diseases. For instance, the introduction of North American beavers in Tierra del Fuego has transformed forests into meadows, significantly altering the habitat. Likewise, invasive species like the Nile perch in Lake Victoria have led to the extinction of native species due to predation. Additionally, invasive species sometimes serve as vectors for diseases affecting both wildlife and human populations, leading to increased health concerns. Therefore, the presence of invasive species often results in ecological imbalance, which can have cascading effects on the ecosystem, including the loss of biodiversity and even the extinction of native species.