Regression plots of genetic differentiation, normalized by distance between populations, represented by pairwise FST per ln(km), versus average distance of each pair of sites to the core (km) along transects 1–6 (a–f). Transects 1, 2, and 6 (a, b, and f) showed significant increases in FST per ln(km) (bolded). Transect 4 (d) showed a significant decrease in FST per ln(km) (bolded). Transects 3 and 5 (c and e) showed no significant pattern in FST per ln(km).