Figure 1 . Sampling and genetic analyses. (A) Map of sampled locations around Yap Island. In the rest of the figure and in the main text names of locations are abbreviated with their initial letters. (B, C) Examples of sampled adult (B) and juvenile (C) colonies. (D) Initial hierarchical clustering of all samples based on identity-by-state (IBS), to detect clones and wrong collections. (E) Ordination plot of the first two principal coordinates of the identity-by-state matrix (filtered dataset). Age classes are identified by indices “A” (adults) and “J” (juveniles) added to the abbreviation of reef site. Ellipses show 75% confidence limits of the data (multivariate normal distribution model). None of the population:age groups are significantly different from any others. Crosses identify positions of the two Nimpal siblings. (F) Deviation of nucleotide diversity (\(\pi\)) from global mean in adults and juveniles from each reef site, computed separately for each chromosome (red lines). The X-axis labels identify age class and give the number of genotyped individuals within each group. (G) Hierarchical clustering tree of the filtered data (same as on panel E) based on relatedness. Insets show site frequency spectra of the detected siblings (“Sib pair”) and two randomly chosen individuals (“Random pair”).