How does the gill raker trait relate to diet breadth in sticklebacks?

• A. More numerous and longer gill rakers are associated with detritivorous or plankton-rich diets; fewer or shorter gill rakers with benthic feeding.
• B. Gill rakers do not relate to diet.
• C. Gill raker length is only influenced by water temperature.
• D. More gill rakers lead to narrower diet.

Answer: (A)

Gill raker morphology directly influences what size prey a stickleback can efficiently filter from the water. More numerous and longer gill rakers increase filtering surface, making it easier to capture many tiny particles like plankton or detritus. This suits detritivorous or plankton-rich diets and helps support a broader, plankton-based foraging niche. In contrast, benthic feeding focuses on larger prey near the bottom, where heavy filtering is less needed, so having fewer or shorter gill rakers is advantageous. In short, gill raker traits adapt to the prey available, linking anatomy to diet type and overall diet breadth.