Travel with your kin ship! Insights from genetic sibship among settlers of a coral damselfish

Coral reef fish larvae are tiny, exceedingly numerous, and hard to track. They are also highly capable, equipped with swimming and sensory abilities that may influence their dispersal trajectories. Despite the importance of larval input to the dynamics of a population, we remain reliant on indirect insights to the processes influencing larval behavior and transport. Here, we used genetic data (300 independent single nucleotide polymorphisms) derived from a light trap sample of a single recruitment event of Dascyllus abudafur in the Red Sea (N = 168 settlers). We analyzed the genetic composition of the larvae and assessed whether kinship among these was significantly different from random as evidence for cohesive dispersal during the larval phase. We used Monte Carlo simulations of similar-sized recruitment cohorts to compare the expected kinship composition relative to our empirical data. The high number of siblings within the empirical cohort strongly suggests cohesive dispersal among larvae. This work highlights the utility of kinship analysis as a means of inferring dynamics during the pelagic larval phase. ; For logistic and fieldwork support, we thank the Coastal and Marine Resources Core Lab at the King Abdullah University of Science and Technology (KAUST) and the R/V Thuwal crew. We thank KAUST's Bioscience Core Laboratory for assistance with Illumina sequencing. We acknowledge Liam Mencel's programming for likelihood inferences; Giacomo Bernardi, Ricardo Beldade, and Suzanne Mills for discussions on the reproductive biology of damselfishes. This research was supported by KAUST baseline research funds to M.L.B.