Figure 2.

Effect of corridor length and corridor width on genetic diversity (Panel A) and genetic differentiation (Panel B). Genetic diversity in the patches increased linearly with increases in corridor area for all species groups (Panel A). Here, corridor area was measured in square kilometers, but the dimensionless design of the model means that these results can scale to any system (see Materials and methods). Notice that species' population sizes, but not dispersal abilities, are important predictors of genetic diversity and that this effect is amplified at increased corridor areas. Genetic differentiation does not increase linearly with corridor area but rather depends on the specific combination of corridor length and width (Panel B). This panel illustrates the effects for species with small population sizes and short dispersal distances and the contour lines and colors indicate values of genetic differentiation between the patches with blue representing low F_ST values and red representing high F_ST values. The precise effects vary between the species groups (see Fig. S2), but for all species, even modest increases in corridor width can result in large reductions in genetic differentiation.