The Toothpick Fish Lab was an exciting lab which allowed students to experiment with genes and the environment with toothpicks. The eight toothpicks all represent three different colored fish. We formed a gene by randomly picking two alleles from a "gene pool".
Green Allele (G) -Dominant to all other alleles
Red Allele (r) -Recessive to G and incompletely dominant to yellow*
Yellow allele (y) -Recessive to G and incompletely dominant to red*
The possible results for the phenotype and genotype are listed below.
Red Allele (r) -Recessive to G and incompletely dominant to yellow*
Yellow allele (y) -Recessive to G and incompletely dominant to red*
The possible results for the phenotype and genotype are listed below.
Green- GG, Gr, Gy
Red- rr
Yellow- yy
Orange- ry
According to all the possible genotypes and phenotypes, two red fish can not mate and have a green offspring. If two red fish mate, then the offspring's phenotype would be 100% red. On the other hand, if two orange fish mate they can have a red offspring. The chances of having a red offspring with this particular genetic cross is 25% red. It is also possible for two green fish to mate and have an orange offspring. In the case the genotypes would need to be Gr and Gy. The recessive allele could be passed down to the second generation.
We started this lab by making a first generation of fish. In order to do this, we pulled out pairs of genes (without looking) and set them aside. After drawing all the genes, we recorded them in our table (shown above). After completing this, the lab told us that the fish live in a very lush and green stream with lots of seaweed and algae. As a result, the green fish are able to camouflage very well into their ecosystem. However, the yellow fish are eaten very quickly and are unable to reproduce. Therefore, all the yellow fish, yy, do not survive. Then, we repeated the same process for the second and third generation (making sure to remove all yellow offspring). At the end of the third generation, only two yellow alleles had remained. After the third generation, there were only nine fish remaining even though we started of with twelve fish. However, this would not happen in the wild because even if the fish were being eaten, they would still continue to reproduce. We repeated this process once again for the forth generation; however, this time we did not remove the yellow fish. This is because the lab informed us that harmful factory waste was recently dumped into the stream, killing majority of the seaweed and algae. This benefits the red, yellow, and orange fish because rocks and sand provide good camouflage. This time all the green fish are eaten. As a result of this environmental disaster, the population has drastically changed. This left us with only three survivors. When the environment was hostile to them, the green alleles disappeared faster than any other color. Due to the fact that "G" was the dominant allele, any genotype with "G" was eaten. Throughout the lab green was the most prevalent color. When the disaster occurred, all the green fish died. Hence, majority of the population.
Red- rr
Yellow- yy
Orange- ry
According to all the possible genotypes and phenotypes, two red fish can not mate and have a green offspring. If two red fish mate, then the offspring's phenotype would be 100% red. On the other hand, if two orange fish mate they can have a red offspring. The chances of having a red offspring with this particular genetic cross is 25% red. It is also possible for two green fish to mate and have an orange offspring. In the case the genotypes would need to be Gr and Gy. The recessive allele could be passed down to the second generation.
We started this lab by making a first generation of fish. In order to do this, we pulled out pairs of genes (without looking) and set them aside. After drawing all the genes, we recorded them in our table (shown above). After completing this, the lab told us that the fish live in a very lush and green stream with lots of seaweed and algae. As a result, the green fish are able to camouflage very well into their ecosystem. However, the yellow fish are eaten very quickly and are unable to reproduce. Therefore, all the yellow fish, yy, do not survive. Then, we repeated the same process for the second and third generation (making sure to remove all yellow offspring). At the end of the third generation, only two yellow alleles had remained. After the third generation, there were only nine fish remaining even though we started of with twelve fish. However, this would not happen in the wild because even if the fish were being eaten, they would still continue to reproduce. We repeated this process once again for the forth generation; however, this time we did not remove the yellow fish. This is because the lab informed us that harmful factory waste was recently dumped into the stream, killing majority of the seaweed and algae. This benefits the red, yellow, and orange fish because rocks and sand provide good camouflage. This time all the green fish are eaten. As a result of this environmental disaster, the population has drastically changed. This left us with only three survivors. When the environment was hostile to them, the green alleles disappeared faster than any other color. Due to the fact that "G" was the dominant allele, any genotype with "G" was eaten. Throughout the lab green was the most prevalent color. When the disaster occurred, all the green fish died. Hence, majority of the population.
The toothpick fish lab showed us how the fish populations changed because of environmental issues. Throughout the lab, we were able to see how the genotypes and phenotypes changed with the environment. This is a clear example of natural selection. Natural selection is a process in which characteristics that make an individual better suited to its environment becomes more common in species.
Changes such as these are also evident in real populations. For example, global warming is adding strength the the El Niño events. Scientist ran many tests to see if the El Niño, from 1997-1998, altered the genetic makeup of Galápagos marine iguana populations. Turns out that the El Niño has much more to it than I thought. If you'd like to learn more on this very interesting topic, visit http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001285.Other environmental changes such as an ice age, oil spill, forest fire, global warming, and much more can have a vivid impact on ecosystems and the genetic composition of animals.
