Fig. 3

Estimated isolation by distance (IBD) as measured by the relationship between pairwise physical distances between sites (km) and pairwise genetic divergences (FST) in Crepidula fornicata (purple) and C. plana (pink). IBD was calculated using a Mantel’s test. C. fornicata exhibited significant IBD, but C. plana did not, potentially due to its relatively lower power (see text)