Ball Drop

Random mutation and natural selection have already found a good solution to this ball packing problem. Can you find a better solution? Your goal is to drop balls into the pit in an order that maximizes the fraction of the pit area occupied by balls. After you play, the app will tell you how well you did compared to the best solution found by 50 generations of natural selection in a population of 50 haploid individuals.

Peppered Moth in the 1800s

This applet lets you explore the effect of assuming different values for the selection coefficient in Haldane’s (1924) model for the decline of the light-colored form of the peppered moth (Biston betularia) in Britain at the height of the industrial revolution.

Peppered Moth in the 1900s

This applet lets you explore the effect of assuming different values for the selection coefficient in a model designed to predict the decline of the melanic (dark) form of the peppered moth (Biston betularia) in Britain after the air became clean again in the late 1900s.

Selective Sweep

This applet starts off with a new beneficial mutation in the center of one chromosome in a population of 25 diploid individuals. Red shading denotes chromosome segments that are identical to the chromosome on which the mutation arose. Each generation, crossing over breaks up the red parts, but the new mutation quickly becomes fixed due to its high fitness. A small region around the mutation is also fixed (hitchhiking) and is shown in dark purple once fixation of the selected gene occurs. Refresh your browser to start again.

Genetic Drift

This applet simulates genetic drift in 5 populations for 500 generations, allowing you to modify the effective population size.

Fst

This applet shows that the effect of genetic drift in small subpopulations is random fixation of alleles, leading eventually to a total lack of heterozygotes (similar to the effects of inbreeding).

Coalescence

This applet simulates random mating for up to 40 generations in a population comprising 5, 10, or 15 diploid individuals. A gene tree for a sample of 5 genes is traced. Play with this app to convince yourself that the MRCA of the 5 sampled genes tends to be deeper if Ne is larger.