2025/09/17 by Patrick J Krug, Danielle Y Trathen, Jennifer Retana +3 · 1 voice
Earth and Planetary Sciences · Agricultural and Biological Sciences · #Marine Biology and Ecology Research #Marine and coastal plant biology #Mollusks and Parasites Studies
paper · doi:10.1093/biolinnean/blaf111
Abstract Species delimitation models are important quantitative tools for facilitating the discovery of cryptic species and clarifying the boundaries between focal taxa. However, distinct evolutionary processes may promote diversification at different points in a radiation, complicating efforts to identify speciation processes and diagnostic characters. Moreover, traits such as dispersal ability can have opposing effects on diversification rate versus population subdivision, which causes coalescent models to oversplit samples. We examined the effects of larval dispersal and host use on population structure and diversity in a Caribbean radiation of photosynthetic herbivores, sea slugs in the genus Elysia. Five methods of species delimitation broadly supported six described taxa and a previously unrecognized taxon, but species with less dispersive offspring were more likely to be oversplit using the multispecies coalescent. Surprisingly, species that shared a phylogeographic break were likely to be split into multiple taxa by coalescent models regardless of dispersal ability. Some host shifts may have contributed to divergence, but others pre-dated speciation, suggesting ecological specialization can promote reproductive isolation but often acted at deeper timescales; recent speciation was more often driven by sea level fluctuations and changes in reproductive anatomy, potentially reinforced by dispersal limitation.