Which trait besides armor plates is often examined in stickleback genetic studies to understand ecological adaptation?

Which trait besides armor plates is often examined in stickleback genetic studies to understand ecological adaptation?

• A. Gill raker number
• B. Fin width
• C. Eye color
• D. Scale thickness

Answer: (A)

Gill raker number is a key trait because it directly reflects feeding strategy and the ecological niche a stickleback occupies. The gill raker apparatus acts like a sieve inside the throat area: more numerous or longer gill rakers improve the ability to filter and capture very small prey, such as plankton, which is common in lake (limnetic) environments. In contrast, populations that feed on larger prey in benthic habitats tend to have fewer, coarser gill rakers. This link between gill raker morphology and diet makes the trait highly responsive to ecological selection and evidence of adaptive divergence, which is why researchers study it alongside armor plates. The other traits—fin width, eye color, and scale thickness—don’t show as consistent a pattern tied to feeding ecology across populations, so they’re not as informative for understanding ecological adaptation in sticklebacks.

Gill raker number is a key trait because it directly reflects feeding strategy and the ecological niche a stickleback occupies. The gill raker apparatus acts like a sieve inside the throat area: more numerous or longer gill rakers improve the ability to filter and capture very small prey, such as plankton, which is common in lake (limnetic) environments. In contrast, populations that feed on larger prey in benthic habitats tend to have fewer, coarser gill rakers. This link between gill raker morphology and diet makes the trait highly responsive to ecological selection and evidence of adaptive divergence, which is why researchers study it alongside armor plates. The other traits—fin width, eye color, and scale thickness—don’t show as consistent a pattern tied to feeding ecology across populations, so they’re not as informative for understanding ecological adaptation in sticklebacks.