Datasets 'Contrasting reproductive and early-life history strategies in recently diverged octocoral species (Paramuricea spp.)'

Species delimitation is central to understanding biodiversity and its conservation, yet genetic divergence alone often provides only ambiguous signals, particularly in marine invertebrates such as corals. Their slowly evolving genomes, cryptic diversity, and complex reproductive modes can obscure species boundaries. This also applies to the two color morphs of the Iberian-Atlantic Paramuricea-complex, an octocoral genus whose species, including those studied here, commonly dominate deep coral gardens. Although the sympatrically occurring yellow and purple morphs show little mitochondrial differentiation, there is evidence of partial genetic structuring.By characterizing gametogenesis, spawning time, and early life-history stages, we reveal pronounced prezygotic barriers between the yellow (broadcast-spawning) and purple (surface-brooding) morphs, including a stable multi-year temporal separation and strongly contrasting fertilization environments. These differences extend into embryonic development, larval morphology, behaviour, and settlement dynamics and reflect divergent dispersal strategies. Overall, our results provide direct biological evidence that the two morphs represent independent evolutionary lineages, supporting their recognition as distinct species. Our model system represents a current example of ecological speciation and may serve future research aimed at understanding the genetic coupling between reproductive modes and life-history traits.