Population Genetics Lab

From the data we can conclude that different traits or parameters can effect a population in many different ways. It can decrease or increase a population depending on the trait. After a hurricane hits Lake Malawi the cichlid fish male population must adapt to the new factors that have been put upon them. Mutation within the population supports the fact that it can cause dominant and recessive allele frequency to decrease. Migration causes the allele frequency to lower as well due to movement of the population after the hurricane. The cichlid male fish with a higher fitness are more suitable for their environment, but when their fitness is lowered, their allele frequency decreases. This

The main purpose of this lab was to utilize the infamous Hardy-Weinberg equilibrium equation to predict the evolutionary modifications a certain species (Drosophila melanogaster) displayed throughout different generations. For this experiment to be carried out, Drosophila melanogaster, also known as fruit flies, were used to visually represent evolutionary conceptions such as Hardy-Weinberg equilibrium equation. At the beginning of the experiment, the parent generation was observed first. Throughout the course of seven weeks, the vial was analyzed for certain changes between the two populations of Drosophila melanogaster; wild type and ebony. Although the genotypes could not be figured out, the flies were evaluated and observed based on

Introduction For the past few weeks in Biology 107, the class has been touching on the subject of evolution and how it is brought about through various processes. Evolution is a concept that has been researched extensively for over a century now and continues to bring interesting findings day after day. According to the Hardy-Weinberg law (a principle that contributes to the understanding of evolution) first introduced by Godfrey Hardy and Wilhelm Weinberg states that there are five possible agents of evolutionary change, including: natural selection, genetic drift, mutations, gene flow, and nonrandom mating. Nonetheless, the mechanism of interest for this particular lab is natural selection.

Most diploid species maintain a one to one sex ratio because it is evolutionarily stable (Fisher, 1930). However, when population ratios do not fit the Fisherian sex ratio of one to one, selection will favor the gene/allele that is in limited supply until their frequency is greater or equal to the competing gene (Fisher, 1930). Therefore, selection works at the level of the gene in maintaining evolutionarily stable Fisherian sex ratios.

The phenotype of an organism is the outward expression of its genotype and possesses different alleles for each gene. Alleles code for different traits and are either dominant or recessive, mutant or wild-type. Natural selection acts against different alleles, organisms, and populations forcing them to adapt and survive. The stronger the natural selection, the weaker the impediment from gene flow. Geographic variations also have an impact on an organism's natural selection through migration— emigration vs immigration. In this paper, Hoekstra et al (2014) studied the organism Chaetodipus Intermedius (pocket mice) and the effects of natural selection.

Researcher’s hypothesis: Natural selection influences the allele frequency by most favorable and most advantageous trait which would increase the fitness of the organisms in the environment. If the hypothesis is true, there is a prediction that the F allele population will grow and there will be no f alleles

The new genetic drift population sort of accurately represents the original population. For example, one of the largest percentages of the Genetic Drift Population was 33% and the largest percentages of the Original Population was 35% for the phenotype green. However, one of the smallest percentages of the Genetic Drift Population was 0% and one of the smallest percentages of the Original Population was 11% for the phenotype brown.

A set of rules and guidelines were followed on how breeding would precede. Pairs in one block could not mate with another, and within a block the alleles were systematically divided and breed to assure inbreeding wouldnt occur. Each allele was assigned the side of a coin. Each generation followed the same guidelines and produced a total of 12 offspring’s (6 male and 6 female). Breeding was mimicked over the course of 8 generations. After the 8th generation of offspring had been produced, the allelic frequencies were recorded in the table

By comparing the single-nucleotide polymorphisms(SNPs) and examining the genetic sequence within a population, researchers can determine if the genetic diversity is caused by natural selection or mutation (Kawabe et al., 2014). As mentioned above, genetic diversity is caused by many factors such as mutations, natural selection, genetic drift and migration (PCG-Denver, 2006). Mutations change the nucleotides in DNA sequence through radiation, chemicals or error during DNA replication while natural selection allows organisms with the fitted allele to survive and spread (“What is Genetic Diversity?” n.d.). In addition, genetic drift changes the gene of a population over time which may lead to loss of beneficial genes and migration enhances gene flow as genes are transferred among populations (Star, B. & Spencer, H. G., 2013). Thus, genetic diversity may be detrimental or beneficial, but it is important for its occurrence because it helps regulate the lifespan of a population by providing gene resistance to diseases and environmental pressures (“What

Genetic drift results in random fixation and a decline in heterozygosity; if the alleles that are fixed are not favorable the average fitness of the individual will decline. This decline in fitness caused by genetic drift is called inbreeding depression.

Totally, our result showed low nucleotide diversity and high haplotype diversity, which may represent a signal of rapid demographic expansion from a small effective population size

Case II selected against the homozygous recessive genotype, meaning there is no homozygous recessive offspring since none of them will survive. The p value was 0.86 while the q value was 0.14. In Case I, the population could produce offspring that was homozygous dominant or recessive, or heterozygous, and the p value was 0.44 and the q value was 0.56. The p and q value for Case I was more equal because there was no selection against the homozygous recessive genotype, meaning there was the homozygous recessive and heterozygous genotypes contributing to the q frequency and the homozygous dominant and heterozygous genotypes contributing to the p frequency in case I. The Case II p and value value is so different compared to the Case I value because Case II could only produce homozygous dominant and heterozygous offspring. Thus, more offspring will contain the dominant allele because the homozygous dominant and heterozygous offspring genotypes were contributing to the p value, while only the heterozygous genotypes were contributing to the q value. Case III had a much higher heterozygote advantage because if the offspring was heterozygous, it automatically survived. But if the offspring was homozygous dominant, you would have to flip a coin to see if the offspring would survive or not. This is reflected in the p and q values of case III, as the p value was 0.72 and the q value was 0.28. While

Initial population is chosen randomly. There is no clear indication as to how large a population should be. The considerations are: if the population is too large, there may be difficulty in storing the data, but if the population is too small, there may not enough strings for crossovers. In our experiments, the population range 20 to 200.

Although the definition of relative fitness is simple, the mathematical relationship between absolute and relative fitness is subtle (Bazykin, 1969; Betzig, 1986 and Beatty, 2008). In particular, there is a curve of diminishing returns between these two quantities i.e., increasing the absolute fitness of a genotype by some amount has less effect on relative fitness (compared with the mean relative fitness) than does decreasing the relative fitness of the genotype by the same amount. The importance of mathematical implication of fitness is straightforward i.e., when zygotes attempt to mature, selection acts, killing some. Because a proportion (W1) of A1 individuals and a proportion (W2) of A2 individuals survive, the proportion of individuals that carry A1 after selection acts is

The relative fitness of a genotype (w) equals to its absolute fitness when get normalized (Betzig, 1986). Barton and Turelli (1989) illustrated that in the normalization process, the absolute fitness of each genotype is divided by the absolute fitness of the fittest genotype, such that the fittest genotype has a relative fitness of one. We can also define a selection coefficient (s), a measure of how much ‘worse’ the A2 allele is than