Final answer:
Human activities, including habitat destruction, the introduction of invasive species, and over-harvesting, have led to a significant reduction in native species in isolated ecosystems like Lake Titicaca, similar to the biodiversity loss observed in Lake Victoria due to the introduction of the Nile perch.
Step-by-step explanation:
The few native species in Lake Titicaca can be attributed to human introduction and manipulation of species. Specifically, human activities such as destruction of habitat, introduction of exotic species, and over-harvesting have caused significant biodiversity loss in ecosystems. This pattern of species loss is evident in locations such as Lake Victoria and Lake Titicaca. The introduction of species like the Nile perch in Lake Victoria has led to the extinction of numerous endemic species, drawing parallels to the situation in Lake Titicaca. Lakes and islands are particularly vulnerable to these threats due to their isolation and unique environmental conditions.
Additionally, the global extinction rate is currently on par with the rates seen during the planet's previous mass extinctions, but with human activity as the primary driver. The rate of species extinction is no longer a slow, natural process, but an accelerated one induced by human influence, which has profound effects on biogeography and biodiversity. These human-induced changes in ecosystems have had a catastrophic impact, especially on isolated environments that host a high number of endemic species, as seen with lakes and islands around the globe.