Siblings
Another key prediction of SRS is occurrence of close kin individuals among same-cohort recruits, and indeed we find a pair of juveniles at Nimpal that were related to each other with pairwise relatedness of 0.33, indicating likely full-sib or half-sib relationship (Fig. 1 G). Their pairwise site frequency spectrum was clearly different from a typical pair of unrelated corals, with more shared heterozygotes and minor allele homozygotes and fewer sites in alternative homozygote states (AA vs aa , Fig. 1 G, inset). This relatedness is unlikely to be an artifact of genotyping since these samples were not outliers in terms of position in the overall PCoA (Fig. 1 E) or depth-quality and the number of sites passing filters (Supplementary Fig. 1).