Question

You are interested in studying the evolution of guppy coloration. In order to do so, you purchase 20 guppies of the same colors from a pet shop. You then put 10 matching fish into each of two large tanks so that the fish populations are phenotypically similar. Guppies lay live young about every month, but guppies will eat their young. To help the baby fish (fry) live, you decorate the tanks with horribly tacky, GloFish® aquarium plants. Tank 1 has yellow plants, and tank 2 has blue plants. After two years of maintaining the tanks, all of the original parents are dead, but the tanks still have 10 guppies each. There are differences in the pigmentation of the fish in the two tanks.

1. The starting and ending sizes of the populations did not change. Does that mean that the populations were in Hardy-Weinberg equilibrium? EXPLAIN

Answer 1

A. The starting and ending sizes of the populations did not change. This is not a criteria of the Hardy-Weinberg equilibrium. In the Hardy-Weinberg equilibrium there should be no natural selection processes such as competition but as we can see the initial and ending populations are the same. According to the question each guppy lays egg every month and after 2 years only the original parents dies and to prevent the parent from eating their young ones we have decorated the tank with Glofish aquarium plants, but this didn't help because if the parents did not eat their young ones then the progeny size should be atleast 100 individuals in each tank. Hence the parents ate their young ones and the 10 which are left were selected through competition. Hence the population was not in Hardy-Weinberg equilibrium.

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