Population Genetics Simulator

This is an online one-locus, two-allele genetic simulation tool, inspired by the classic population genetics program PopG. It can simulate multiple subpopulations and enables you to observe the effect of natural selection, mutation, migration, and genetic drift on allele frequencies.

It calculates allele frequencies in each generation according to the Wright–Fisher model, one of the foundational models in population genetics used to describe the evolutionary dynamics in finite populations, which assumes that there is no overlap of generations, and that each copy of the gene found in a new generation is drawn independently and at random from all copies of the gene in the previous generation.

How to use the simulator

1. Set your parameters: Indicate the population size per subpopulation, fitness values for the three genotypes, mutation rates in each direction, migration fraction, initial allele frequency, number of generations, and the number of subpopulations. Keep in mind that larger population sizes, more generations run, and more subpopulations will lead to higher memory use and longer runtimes (for reference: the original PopG has a hard limit of 1,000 for the number of simultaneously-evolving subpopulations and 10,000 for the size of each), and above 25 subpopulations the chart starts to become pretty messy although the summary statistics may still be of use.

2. Optional seed: Provide a random number seed if you want identical outcomes each run (blank yields a new random set).

3. Run Simulation: Click 'Run Simulation' to watch the frequency of Allele A evolve over time in each subpopulation.

4. Results & Analysis:

• The simulator plots a line chart of allele frequencies vs. generation for each subpopulation.

• A legend below the chart indicates each subpopulation line’s colour.

• A vivid blue line shows what the gene frequencies would be in an infinite population with no drift.

• You can hover over a data point with your cursor to view exact values.

• The summary section highlights the number of subpopulations with Allele A or a fixed, plus the mean allele frequency across all subpopulations.

5. Download Chart: A 'Download Chart as PNG' button lets you export the graph.

Go ahead and test various selection intensities, mutation rates, and migration fractions to see how allele frequencies respond!