TA: Yuliana Rowe
Instructor: Dr. Molumby
Section: BIO 101
23 November 2018
A group of organisms of same species, residing in same place within a certain area forms population. Each individual has genotype, composed of alleles at different loci which are fixed and cannot be change. Genotypes cannot be changed but frequency of alleles located at locus can be changed which depends upon different stochastic process (Molumby & Murray, 2018). Changing in allele frequency results into change in genetic variation and in case of small population, loss of genetic variation is highly observed. Genetic variation describes naturally occurring genetic differences among individuals of the same species (Scitable, 2014). Migration is an event by which the allele of one population moves to another population. After mating is established between migrating individual and destination individual, the migrating individual contribute gamete carrying the alleles that can alter the existing proportion of the alleles in the destination population which sometimes results into loss of genetic variation (nature.com, 2014)
Null Hypothesis: Migration changes the allele frequency within small population
1. This experiment was done by using Pop-U-Gen cards. For the initial collection 6AA, 12 Aa and 6 aa cards were taken to make up a stack of 24 cards in total.
2. by using the formula, P= Freq (AA) + ½ Freq (Aa), q= Freq. (aa) + ½ Freq (aa) initial genotype frequencies were found.
3. After that cards were shuffled and four pair of 2 cards, total 8 cards were drawn out randomly.
4. Each of these pair of card were genetic crosses between two hermaphrodites.
5. Assuming that each pair produce 6 offspring, the first pair cross between AA and AA were observed for which 6 AA cards were put as offspring
6. For crosses having aa and aa, 6 aa cards were put as offspring.
7. For the crosses having AA and Aa, coin was flipped 6 times, for each head , AA and for each tail Aa card were added to make 6 offspring
8. For the crosses having aa and Aa, coin was flipped 6 times, for each head , aa card was added to the stack and for each tail , Aa card was added t the stack thus 6 offspring were created to this cross.
9. For the cross having Aa and Aa, coin was flipped twice, six time in succession. Each time two heads came out; AA card was added in the stack. When heads and tail were observed, Aa card was added to the stack and when two tails drawn out, aa card was added, thus making 6 offspring for the cross between Aa and Aa.
10. When every stack was completed, by using the formula, the genotype frequencies were calculated which made the 1 generation
11. For the 2 generation the entire sequence from making offspring to calculating the genotype frequencies were repeated.
12. This procedure was continued till 5 generations were made.
13. For the second part, same procedure was followed, only this time, starting with 1 generation, 1 card was exchange to anther lab partner and the calculations were carried out with a new card every single time for every generation.
14. This movement of card was made to carry out the allele flow between different partners.
15. Calculations were done, and results were plotted.
The results obtained by the data collected shows the allele frequency of homozygous dominant allele (AA) before and after movement of allele from one destination to another.
In this experiment, both process of immigration and emigration is observed. As can be seen by the data obtained from the class in the form of histogram, allele frequency of small population changes drastically compared to that in large population where migration have a little or no impact on allele frequency.
In this experiment, the hypothesis being tested cannot be rejected as the results and the statistic supports that migration causes change in allele frequency during different generations within small population of 24 cards.
A study shows that migration and natural selection disturb hardy wein berg equilibrium by changing genotype frequencies in populations. Migration can increase or decreases allele frequencies of population. The experiment carried out shows that the frequency of homozygous dominant is higher in northern moth population while frequency of homozygous recessive allele is higher in southern moth population. When recessive allele from south migrates to north, the allele frequency of northern moth population shifts resulting in more homozygous and heterozygous recessive genotypes.
Before the migration, there is no allele flow and the genetic variation is preserved, however after the immigration and emigration between different lab partners, the allele flow occurs which causes changes in allele frequencies and after several generation the genetic variation gets lost.
The reverse can also be possible if the allele which is migrated doesn’t able to survive or by some other means doesn’t able to reach the destination then the condition would be same as initial.
The overall effect shows that if the genotype aa migrate to the destination having Aa and Aa, they will increase the relative allele frequency of ‘a’. however, if the aa which migrated doesn’t able to survive in the destination, the changes brought by initial migration would be reversed. (nature.com, 2014)
first humans evolve in the land of Africa 60,000 years ago. The footprints they left and the by mapping the appearance and genetic markers the arrows were created all around the world. This includes different species of human and how they evolve overtime. (National geographic, 2018)
These incidents of migration cause the changing in allelic frequency where sometimes founder effect and sometimes bottle neck effect were observed, for example the early men from cave to jungles and from jungles to other places migrate and thus thy evolve overtime. Due to this thing occurred in large population it take 1000 of years to evolve completely compare to the changes occur in smaller population such as beetles. (Drees, 2011)
The experiment of Pop-U-gen cards was carried out to determine and test the hypothesis which suggest that migration cause change in allele frequency within small population. By performing calculation using the hardy wein berg equation P2 + 2pq +q2= 1 and finding the genotype frequencies of homozygous and heterozygous alleles of 5 generations, the result was determined. Results and the statistics supports the Null hypothesis and thus it cannot be rejected.
Drees, C. ;. (2011). gene flow in ground beetle.
Molumby, A., ; Murray, D. (2018). In A. Molumby, ; D. Murray, adventures in populations and communities (pp. 53-55). champaign: stipes publishing L.L.C.
National geographic. (2018). Retrieved from National geographic: https://genographic.nationalgeographic.com/human-journey/
nature.com. (2014). Retrieved from www.nature.com: https://www.nature.com/scitable/topicpage/the-genetic-variation-in-a-population-is-6526354