Parentage analyses identify local dispersal events and sibling aggregations in a natural population of Millepora hydrocorals, a free-spawning marine invertebrate

<p><span><span><span><span><span><span><span><span><span><span><span>Dispersal is a critical process for the persistence and productivity of marine populations. For many reef species, there is increasing evidence that local demography and self-recruitment have major consequences on their genetic diversity and adaptation to environmental change. Yet empirical data of dispersal patterns in reef-building species remain scarce. Here, we document the first genetic estimates of self-recruitment and dispersal distances in a free-spawning marine invertebrate, the hydrocoral <i>Millepora platyphylla</i>. Using twelve microsatellite markers, we gathered genotypic information from 3,160 georeferenced colonies collected over 9,000 m² of a single reef in three adjacent habitats in Moorea, French Polynesia; the mid slope, upper slope, and back reef. Although the adult population was predominantly clonal (85% were clones), our parentage analysis revealed a moderate self-recruitment rate with 8 to 37% of sexual propagules produced locally. Assigned offspring often settled at less than 10 meters from their parents and dispersal events decrease with increasing geographic distance. There were no discrepancies between the dispersal distances of offspring assigned to parents belonging to clonal <i>versus</i> non-clonal genotypes. Inter-habitat dispersal events via cross-reef transport were also detected for sexual and asexual propagules. Sibship analysis showed that full siblings recruit together on the reef (more than 40% settled at &lt; 30 m), resulting in sibling aggregations. Our findings highlight the importance of self-recruitment together with clonality in stabilizing population dynamics, which may ultimately enhance local sustainability and resilience to disturbance.</span></span></span></span></span></span></span></span></span></span></span></p>