On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time.
When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.
If one builds a canal linking a predator-rich pond to a predator-poor pond, then what type of selection should subsequently be most expected among the mosquitofish in the original predator-rich pond, and what type should be most expected among the mosquitofish in the formerly predator-poor pond?
A) stabilizing selection; directional selection
B) stabilizing selection; stabilizing selection
C) less-intense directional selection; more-intense directional selection
D) less-intense disruptive selection; more-intense disruptive selection

Question

Quizplus · Accepted Answer

When the predator-rich pond is connected to the predator-poor pond, there will be gene flow between the two populations of mosquitofish. As a result, the directional selection for short, fast bursts in the predator-rich pond will likely become less intense because some of the genes for continuous swimming from the predator-poor pond will enter the population. Similarly, the directional selection for continuous swimming in the predator-poor pond is expected to become more intense because some of the genes for short, fast bursts from the predator-rich pond will enter the population. Therefore, the answer is less-intense directional selection for the predator-rich pond and more-intense directional selection for the formerly predator-poor pond.

On the Bahamian Island of Andros, Mosquitofish Populations Live in Various