This file replaces a previous version that had contained erroneous one-base pair shifts in locus 181. This shift was due to allele calling errors for samples from Mexico, only. The following alleles of locus 181 were previously reported as one-base pair too small: 152, 155, 158, 161, 164, 167, 197. The correct allele sizes are 153, 156, 159, 162, 165, 168 and 198. This reduces the total number of alleles for locus 181 from 25 to 18. No samples from Mexico were included in the age calculations or the STRUCTURE analyses, thus the conclusions of the paper do not change. Mexico samples were only used for Figure 5 which plots the proportion of nonmosaic genets per reef as a function of clonal richness at each reef. Because genets never occur in more than one reef and allele calling was consistent within each reef, the number of genets remains unchanged and therefore the data underlying Figure 5 did not change after correcting the errors. However, researchers that intend to use the data for population genetic analysis should use the corrected data set.