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Genetic drift HTML5

Summary

The animation the role of chance in evolution illustrates that the simple game of chance leads to a loss of biodiversity. This animation takes the same idea in the case of sexual reproduction for diploid organisms.

This may seem counterintuitive, but the simple random mixing of alleles inevitably leads to a loss of genetic diversity. The graph shows the evolution over time of the frequency of alleles over generations. A marker identifies in which generation an allele is lost. The objective of this simulation is to confirm the hypothesis that the lower the number of individuals in a population, the faster the decline in diversity.

As is often the case in statistics, it is important to carry out several draws with the same starting number of individuals before drawing any conclusions. This may raise the question whether there is a relationship between the size of a population and the number of generations at the end of which there remains only one allele for a given gene.

A comparative study between two draws from the same initial conditions (numbers, genotypes) makes it possible to approach certain theories of evolution such as the founder effect, ecological insularization, bottleneck...

It should be noted that the "Activate mutation" option illustrates that genetic drift can also be a source of diversity by revealing and spreading new genes.

Learning goals

  • To develop and validate hypotheses to explain what mechanisms may account for the loss of diversity in a population.
  • To define the link between genetic drift and population size.