Comparison of allelic richness and observed heterozygosity. Means of allelic richness and observed heterozygosity compared between western North Atlantic and Mediterranean populations of Oculina spp. (a), and between western Mediterranean (Spain and Italy) and eastern Mediterranean (Greece, Lebanon, and Israel) Oculina patagonica populations (b). Bars represent standard deviations. Asterisks represent significant differences as determined by t-tests.