Contrasting patterns of population structure and historical dynamics between two octopus species, Eledone moschata (Lamarck, 1798) and Eledone cirrhosa (Lamarck, 1798), in the Mediterranean basin

Understanding the ecological and evolutionary history of marine organisms is critical for the sustainable management of marine resources. Accurate identification of biologically relevant management units, aligned with biological rather than political boundaries, is fundamental to preserving biodiversity, maintaining ecosystem function, and ensuring sustainable fisheries. We assessed genetic diversity, population structure, and demographic history in two closely related octopus species, Eledone moschata and Eledone cirrhosa, using mitochondrial Cytochrome c oxidase subunit 1 (COI) sequences and genome-wide SNP markers from populations across the Mediterranean and adjacent Northeast Atlantic. We found clear genetic differentiation among E. moschata populations, notably isolating the Adriatic group, likely reflecting limited connectivity influenced by this species’ habitat preferences and life-history traits, such as holobenthic development and restricted dispersal. Conversely, E. cirrhosa exhibited broad genetic connectivity within Mediterranean populations, attributed to its ecological plasticity, extensive larval dispersal, and habitat continuity. However, we identified significant genetic differentiation between Mediterranean and Atlantic populations of E. cirrhosa, reflecting historical colonization events and contemporary oceanographic barriers such as the Strait of Gibraltar. Demographic analyses further revealed distinct historical population dynamics shaped by Pleistocene climatic fluctuations. These contrasting genetic and demographic patterns underscore the need for species-specific management strategies tailored to ecological niches and life-history traits.