The “origin of this species” lies in the pages of the journal Biometrika and precedes the birth of either of the authors. There, in his remarkable landmark 1951 paper “Random dispersal in theoretical populations,” . Skellam made a number of observations that have profoundly affected the study of spatial ecology. First, he made the connection between random walks as a description of movement at the scale of individual members of some theoretical biological species and the diffusion equation as a description of dispersal of the organism at the scale of the species’ population density, and demonstrated the plausibility of the connection in the case of small animals.
