Did all Alaska lake stickleback populations undergo exactly the same evolutionary changes during freshwater adaptation?

• A. True
• B. Not enough data
• C. Only some populations
• D. False

Answer: (D)

The main idea is that evolution in response to freshwater in Alaska sticklebacks follows a similar direction across many populations, but the exact changes aren’t identical in every lake. Many freshwater populations show common trends—like reduced armor plates and shifts in body shape that help them thrive in new environments—but the degree and specifics of those changes vary from lake to lake. Different lakes present different predator pressures, prey types, and ecological contexts, and the starting genetic variation in each population isn’t the same. As a result, some populations converge on similar traits through similar genetic routes, while others achieve different versions of those traits or use different genetic changes altogether. So, it’s not correct to say all populations underwent exactly the same evolutionary changes.