AlleleA1 is an interactive software simulation of evolution at a single locus in an ideal population of imaginary organisms. The locus of interest has 2 alleles: A1 and A2. The user enters values for parameters controlling selection, mutation, migration, genetic drift, and inbreeding. As the simulation runs, the software plots a graph showing the frequency of allele A1 over time. This webpage has application programs for both Mac and Windows systems, as well as a tutorial (pdf version) to guide the user through the program.