Laboratory 8, AP Biology 2012
Spurthi Tarugu, Cade Blankenship, Phuong Nguyen, Kavinmozhi Caldwell, Tyler Truax
In nature, it is survival of the fittest. Each organism has many genes that code for many different characteristics. For example, lizards that have camouflaging capabilities often survive more often than those without camouflaging capabilities. Over the years, the lizards that cannot blend into the environment will die out, and as they die out, those genes will also leave circulation. Soon, there will only be camouflaging lizards. In this way, nature slowly weeds out the weak, and the strong prevail.
The purpose of the lab is to stimulate natural selection as seen in nature in the span of many years. Specifically, we are observing how rabbits with fur and rabbits without fur compare in the survival of the fittest. What we learned, and our results, are explained below.
To simulate random genes being passed down from parent to offspring we at random matched beads together out of a bowl. We had two different colors, red for F and white for f. We picked two at random to get the gene of the new offspring. If we had a pair of white beads together (f,f,) we pulled them out of the bowl so they were no longer an options. The f’s were doomed to die out because the only way that they could stay in the bowl was the be paired up with a F, if they did that however they would be unseen due to the dominant trait attached to it. Eventually, on the dominant gene would show up making the receives gene never to be seen.
Gene Frequency Data
Our original hypothesis was that over several generations, natural selection will cause the frequency of the “f” allele to diminish. Based on our lab data, we can see that our hypothesis is proven correct and therefore there is no need to change it. The number of alleles for the dominant characteristic stays constant (50) throughout the experiment while the number of alleles for the recessive characteristic reduced more than 50% from generation 1 to generation 2 and then continuously started to decrease in numbers. When there were an equal amount of dominant and recessive alleles at the beginning of our experiment, the recessive alleles started waning rapidly. However, towards the end of our lab, the recessive allele did not decrease as quickly while the dominant allele remained constant the whole time. All of our class’s data was similar. The f allele frequency decreased rapidly at the beginning and slowly stopped decreasing at the end of the experiment.
In a real rabbit habitat new animals often come into the habitat (immigrate), and others leave the area (emigrate). The emigration and immigration affect the gene frequency of F and f in this population of rabbits because the gene frequency of F and f will either decrease to some points or increase at others.However, over time, the population will always go back to normal and balance out again. To simulate this, we could have added more red beads or more white beads at certain times and taken out some red and white beads for different trials.
This simulation is an example of evolution because over time, only the fittest animals survive and any gene that is not compatible in the wild will eventually die out or be hidden behind a dominant gene.
The purpose of this lab was to simulate natural selection. As you can see through our collection of data the “f” allele in the rabbits was almost completely demolished by the “F” allele. This shows how natural selection will eventually wipe out recessive genes if the environment continues to be the same.
“LabBench.” Prentice Hall Bridge Page. Web. 28 Mar. 2012. <http://www.phschool.com/science/biology_place/labbench/lab8/intro.html>.