Toothpick Fish Lab

For this lab, we had to "mate fish", and take note of what color offspring it produces. But certain colors didn't blend well, causing those fish to die. The different phenotypes were green, red, yellow and orange, while the possible genotypes were GG Gr Gy rr yy ry (G=green, r=red, y=yellow). The green was dominant while the red and yellow alleles were recessive to the green, but co-dominant to each other resulting in orange when combined. We first pulled out eight green fish, two red fish, one yellow fish and one orange fish. All of the yellow fish died as a result of a lack of camouflage. For the next generation, the population number decreased because there was one less fish to mate. We pulled out seven green fish, two red fish, no yellow fish and two orange fish, therefore none of our fish had to be put in the morgue. In the third generation, we had seven green fish, one red fish, two yellow fish, and one orange fish. The two yellow fish that were produced died and had to be put in the morgue. With two less fish in the mix, the population decreased even more. Six green fish, two red fish and one orange fish were produced in the fourth generation, but then a natural disaster occurred; all of the seaweed and algae died. The green fish then had no camouflage, so all the green fish became extinct; hence, a drastic population decrease. The survivors of the fourth generation were two red fish and one orange fish.

Over time, the population decreased greatly because of the many deaths of a certain color fish. The reason that all of the yellow alleles have not become extinct is because it is recessive to one color and co-dominant to another. For that reason you could have a green fish with a yellow allele that would not have been killed within the first three generations. You could also have an orange fish with one red allele and one yellow which also would not have died. On the other hand, the green fish became extinct so quickly because green is dominant. Any fish with in the fourth generation with a green allele died, causing all green alleles to become extinct. Since the red fish and orange fish cannot mate to make green (because non of them carry a green allele) there will not be another green fish