dispersal kernels used: Gaussian versus fat-tailed. Spatially explicit simulations of ecological drift were carried out using the two dispersal kernels shown, namely a Gaussian model and a particular fat-tailed model called the ‘2Dt’ distribution. The parameters for the kernels used in simulations (and plotted here) are as follows (see text for justification): σ = 40 m, u = 300 m², P = 0.5. Note that the Gaussian produces higher probabilities of intermediate dispersal distances 30–100 m, whereas the fat-tailed distribution produces higher probabilities of both local and long-distance dispersal.