medium · SAT Reading & Writing

The 'Allee effect' is a phenomenon in biology in which a population's per capita growth rate decreases as its density falls below a certain threshold. In small populations, individuals may struggle to find mates or provide group defense against predators. Ecologists argue that understanding the Allee effect is critical for conservation, as endangered species may fail to recover even if the original causes of their decline, such as hunting, are removed. Based on the text, which choice best explains why a small population might continue to decline even after hunting has ceased?

1. Because their low numbers make it physically difficult for them to reproduce or protect themselves.
2. Because hunting has caused a permanent change in the species' genetic makeup.
3. Because the species has reached its 'threshold' and is now physically too large for its environment.
4. Because hunting is the only external factor that can trigger the Allee effect in an ecosystem.

Sign up free to see the explanation and track your rank →