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?

Question

Quizplus · Accepted Answer

In a large lake with a high density of these fish, disruptive selection is the most likely type of selection to occur. This is because the longer gill rakers are advantageous for capturing open-water prey, while the shorter gill rakers are better for capturing shallow-water prey. Therefore, individuals with intermediate gill-raker lengths are likely to be at a disadvantage as they cannot efficiently capture either type of prey, leading to selection against this phenotype and potentially favoring the extremes of gill-raker length.

Three-Spined Stickleback Fish (Gasterosteus Aculeatus) Show Substantial Heritable Variation in Gill-Raker