Latitudinal Differences between Palau and Yap in Coral Reproductive Synchrony

Abstract

Twenty-seven species of coral were examined for reproductive activity in Palau during late spring and early summer 1993, and 10 species in Yap during the last week of May 1993. Thirteen species in Palau were gravid, and six were observed spawning during the week following Mayor June full moon. Spawning occurs over a minimum of 4 months in Palau. By contrast, all 10 coral species sampled in Yap, 420 km to the northeast, were well synchronized for a mass spawning event after June full moon. Intra- and interspecific spawning at equatorial latitudes is less tightly synchronized than at higher latitudes in the central Pacific. Opportunities for hybridization are a function, in part, of interspecific spawning synchrony. If hybridization serves as a mechanism for speciation in corals, then regions characterized by multispecies spawning events are more likely to serve as sites of speciation than those where spawning is more asynchronous.