When fish release their gametes into open water for fertilization, ____ isolation usually prevents the fusion of egg and sperm from different species.

A) ecological
B) gametic
C) temporal
D) behavioral
E) mechanical

Gametic isolation refers to the prevention of fusion of gametes from different species. This is because the proteins on the surface of the egg and sperm must recognize and bind specifically to each other, and if they do not match, fertilization cannot occur. It is a type of prezygotic reproductive isolation that prevents the formation of a hybrid zygote. Ecological isolation, temporal isolation, and behavioral isolation are also prezygotic mechanisms, while mechanical isolation is a type of postzygotic barrier.