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Evolution encompasses genetic changes in populations over time, offering valuable insights into the study of specific gene frequencies and allele compositions within a population. These frequencies can be influenced by various factors, including natural selection, mating patterns, gene mutations, and migration. In this laboratory investigation, we focused on two critical phenomena: genetic drift and the founder effect.
Genetic Drift: Genetic drift, as defined by Berkeley, occurs when, by chance, certain individuals leave behind more descendants and genes in each generation.
Consequently, the genes of the next generation are those of the "lucky" individuals, not necessarily the fittest or "better" individuals. This phenomenon affects all populations, as they are subject to the unpredictable whims of chance (Genetic Drift).
Founder Effect: The founder effect, also described by Berkeley, transpires when a new colony is established by a few members of the original population. The reduced population size in the colony leads to decreased genetic variation compared to the original population, with the gene pool of the new colony representing a non-random sample of genes from the source population (Bottlenecks and Founder Effects).
In this experiment, plastic beads of three different colors (white, green, and red) were employed to represent three distinct alleles of a gene within a haploid individual.
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Each experimental group commenced with an initial population of 100 beads, signifying a diverse starting allele composition.
Two primary scenarios were explored:
The surviving population then expanded back to its original size of 100 beads. This process, involving the random elimination of half the population and its subsequent recovery, was repeated five times. The outcome demonstrated the impact of genetic drift on allele frequencies within the population.
The table below illustrates the outcomes of two distinct experiments, each representing a genetic shift driven by different evolutionary mechanisms. The first part of the experiment focused on demonstrating random genetic drift within a population of 100, represented by different colored beads (white, red, and green). Each group conducted the experiment five times with varying initial compositions. The second part of the experiment aimed to illustrate the founder effect within a population of 100, where five randomly selected beads served as the founders of a new population.
| Group | Experiment Type | Generation | White (w) | Red (r) | Green (g) |
|---|---|---|---|---|---|
| Group 1 | Genetic Drift | 1 | 60 | 20 | 20 |
| 2 | 50 | 48 | 2 | ||
| 3 | 66 | 16 | 18 | ||
| 4 | 62 | 20 | 18 | ||
| 5 | 78 | 12 | 10 | ||
| Founders Effect | 1 | 20 | 40 | 40 | |
| 2 | 20 | 40 | 40 | ||
| 3 | 20 | 80 | 60 | ||
| 4 | 40 | 60 | 60 | ||
| 5 | 40 | 60 | 60 |
Table 1: The table above displays the results obtained from the experiment, showcasing the outcomes of both genetic drift and founder effect. Each experimental group conducted the experiment five times to ensure accuracy.
This experiment provided valuable insights into the consequences that a natural disaster or the random separation of a subset of individuals can have on a population. Both scenarios led to diverse outcomes in the extent of allele changes within the population. Across all four experimental groups, when five beads were separated from the rest of the population to demonstrate the founder effect, it consistently resulted in the elimination of one of the alleles due to random evolutionary events.
In the first half of the experiment, where fewer individuals were removed from the initial population, the degree of change was less pronounced. Additionally, the starting allele frequencies had a significant impact on the final population composition. Higher initial allele frequencies tended to persist in the population, while lower frequencies increased the risk of allele elimination. These findings have practical implications for managing endangered species.
Research conducted on the efficiency of selecting representatives for establishing captive breeding programs in rapidly declining populations aligns with our experiment's results. To maintain 95% of the genetic diversity, a founding population of 150 individuals was determined to be necessary (Miller, Webb). These results mirror the outcomes of our experiment's founder effect section, suggesting that this evolutionary mechanism may not be the ideal choice for assisting endangered species. The higher probability of certain genes being eliminated makes it a less desirable option.
Genetic Drift and Founder Effect Experiment Report. (2024, Jan 23). Retrieved from https://studymoose.com/document/genetic-drift-and-founder-effect-experiment-report
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