Question

Background: You perform an artificial selection experiment in the laboratory on the fruit fly Drosophila. You release 100 flies to start your population into a long tube that has light on one end, and is completely dark on the other end, with food distributed throughout. Most flies hang out in the middle of the tube where it is partially light. Every generation, you pick the eight flies closest to the light end, and the eight flies closest to the dark end, and put those 16 flies into a new, empty version of the light/dark tube to start the next generation of the population. After 50 generations, you observe that no flies spend time in the middle of the tube; all congregate at one end or the other.

Question: Explain why the flies evolved to prefer either light or dark.

Your answer:

Sentence 1: Describe the variability that was initially present in your starting population.

Sentence 2: State which individuals had the highest fitness, and why.

Sentence 3: Explain what evolutionary force acted on the population, and why and how it acted.

Sentence 4: Describe how the population evolved. Be as specific as you can (e.g., say “increased” or “decreased”, rather than just “changed”.)

Answer 1

Answer- the variability in the first generation was the adaptation to live in light as well as dark. The highest fitness was of the flies living either near light or near dark because they were able to survive even after so much generations. The evolutionary force, artificial selection acted on the species as they were provided with the environmental conditions which make them to inherit the characters. The population of light side and dark side both increased.