Which anatomical feature, besides armor plates, is commonly studied in stickleback genetic analyses to understand ecological adaptation?

Which anatomical feature, besides armor plates, is commonly studied in stickleback genetic analyses to understand ecological adaptation?

• A. Pectoral fin width
• B. Gill raker number
• C. Eye diameter
• D. Dorsal fin height

Answer: (B)

Ecological adaptation often shows up in how morphology aligns with feeding strategies, and genetic analyses look for traits that consistently track those ecological shifts. In the stickleback, the number of gill rakers is a classic example. Gill rakers are the comb-like bones on the inner gill arches that help filter prey from the water. More gill rakers are advantageous for capturing very small prey like plankton, which is common in pelagic feeding, while fewer gill rakers suit larger, bottom-dwelling prey. This pattern repeats across marine and freshwater populations and among lakes, making gill raker number a reliable, measurable trait that researchers can map to genetic differences. That’s why it’s a staple in studies of ecological adaptation alongside armor plates. Other traits listed can vary with the environment, but they don’t show such a clear, consistent link to a specific feeding niche across many stickleback populations, so they’re not as informative for studying ecological adaptation through genetic analyses.

Ecological adaptation often shows up in how morphology aligns with feeding strategies, and genetic analyses look for traits that consistently track those ecological shifts. In the stickleback, the number of gill rakers is a classic example. Gill rakers are the comb-like bones on the inner gill arches that help filter prey from the water. More gill rakers are advantageous for capturing very small prey like plankton, which is common in pelagic feeding, while fewer gill rakers suit larger, bottom-dwelling prey. This pattern repeats across marine and freshwater populations and among lakes, making gill raker number a reliable, measurable trait that researchers can map to genetic differences. That’s why it’s a staple in studies of ecological adaptation alongside armor plates.

Other traits listed can vary with the environment, but they don’t show such a clear, consistent link to a specific feeding niche across many stickleback populations, so they’re not as informative for studying ecological adaptation through genetic analyses.