Question

Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?

Answer 1

disruptive selection

Step-by-step explanation:

Disruptive selection is a type of selection which favours extreme values of a trait over intermediate values. E.g. long gill rakers or short gill raker, it will not favour intermediate gill raker length. Since the genetic variation is long gill rakers for open-water feeders and short gill raker for shallow water feeder, the lake will be made of mainly fish with long gill raker or short gill raker, there will not be intermediate, this is disruptive selection which is necessitated by the nature of the lake (open water in the middle and shallow water around the sides).