Final answer:
The larger number of large mammals in Africa compared to other continents is due to Africa's suitable habitats, earlier human coexistence with these species, and effective conservation practices despite challenges like poaching. The decline in large mammals elsewhere, often due to human activities, results in significant ecological impacts and disrupted ecosystems.
Step-by-step explanation:
The existence of numerous large mammals in Africa as compared to other continents is the result of various factors including historical human activities, habitat suitability, and conservation efforts. Historically, human alteration of ecosystems has led to the extinction of large mammals, particularly on continents such as Australia and the Americas where human arrival correlated with a swift decline in these animals. In comparison, Africa and Eurasia experienced human presence much earlier, allowing for a longer period of coexistence and adaptation.
Africa's unique ecosystems, such as the vast savannas, provide an abundant supply of grasses which are crucial food sources for many large grazing mammals. This abundance supports large herds and promotes biodiversity. Additionally, conservation efforts in Africa, including creating national parks and game preserves, have played an important role in protecting these species despite challenges such as poaching.
Conversely, the loss of large mammals in other regions has often been catastrophic, leading to trophic cascades and altered ecosystems, such as the loss of carnivores leading to herbivore overpopulation and subsequent vegetation depletion. Protecting large mammals can also have an umbrella effect, conserving a greater diversity of smaller organisms and maintaining ecosystem health.