Figure 1.

Schematic depiction of a 3 × 3 SW (cross-hatched cells) nested within a 5 × 5 BW (shaded cells; any individual within two cells in any direction can be a parent of an offspring in a focal cell in the SW). Individuals from the outer ring of unshaded cells are within two cells of the sample window, and therefore all individuals within this 7 × 7 grid are potential parents of individuals in the sample. The numbers in each cell are the number of cells in the sample window to which a parent could potentially contribute offspring; these numbers thus reflect the relative probabilities of each cell being chosen as the parent of an individual in the sample.