Schoener and Spiller's studies, in which lizards were introduced into islands in the Bahamas, showed that lizards _______ the densities of common spiders and _______ the densities of rare spiders.
A) decreased; decreased
B) increased; decreased
C) decreased; increased
D) increased; increased

Question

Quizplus · Accepted Answer

Lizards are predators of spiders. So, when lizards are introduced into an island, they will eat some of the spiders, which will decrease the density of spiders. However, lizards are more likely to eat common spiders than rare spiders. This is because common spiders are more abundant and easier to find. So, the introduction of lizards will decrease the density of common spiders more than the density of rare spiders.

Schoener and Spiller's Studies, in Which Lizards Were Introduced into Islands