Natural history and molecular evolution of demersal Mediterranean sharks and skates inferred by comparative phylogeographic and demographic analyses

• DOI: 10.7717/peerj.5560
• Publication Date: 2018-09-18T08:46:27Z
• Authors: Alice Ferrari; Fausto Tinti; Victoria Bertucci...; Alessandro Velonà; Rita Cannas; Ioannis Thasitis; Filipe Oliveira C...; Maria Cristina Fo...; Daniel Golani; Farid Hemida; Sarah J. Helyar; Cecilia Mancusi; Antonello Mulas; Fabrizio Serena; Letizia Sion; Marco Stagioni; Alessia Cariani
• Keywords: 570; QH301-705.5; Natural history; Catsharks,; North-Eastern Atlantic Ocean; Chondrichthyans; Sicilian channel,; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; Skates,; 03 medical and health sciences; /dk/atira/pure/sustainabledevelopmentgoals/climate_action; Mediterranean sea,; name=SDG 14 - Life Below Water; /dk/atira/pure/sustainabledevelopmentgoals/climate_action; name=SDG 13 - Climate Action; 14. Life underwater; Biology (General); Catsharks; Demography; 0303 health sciences; Ciências Naturais::Ciências Biológicas; Science & Technology; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water; R; Skates; Demersal elasmobranchs; Chondrichthyans, Phylogeography, Demography, Natural history, Demersalelasmobranchs, Mediterranean sea, Sicilian channel, Catsharks, Skates, North-Eastern AtlanticOcean; Chondrichthyans; Phylogeography; Demography; Natural history; Demersal elasmobranchs; Mediterranean sea; Sicilian channel; Catsharks; Skates; North-Eastern Atlantic Ocean; name=SDG 13 - Climate Action; Phylogeography; Biogeography; Mediterranean sea; Medicine; Sicilian channel; Demography,

BackgroundThe unique and complex paleoclimatic and paleogeographic events which affected the Mediterranean Sea since late Miocene deeply influenced the distribution and evolution of marine organisms and shaped their genetic structure. Following the Messinian salinity crisis and the sea-level fluctuations during the Pleistocene, several Mediterranean marine species developed deep genetic differentiation, and some underwent rapid radiation. Here, we consider two of the most prioritized groups for conservation in the light of their evolutionary history: sharks and rays (elasmobranchs). This paper deals with a comparative multispecies analysis of phylogeographic structure and historical demography in two pairs of sympatric, phylogenetically- and ecologically-related elasmobranchs, two scyliorhinid catsharks (Galeus melastomus,Scyliorhinus canicula) and two rajid skates (Raja clavata,Raja miraletus). Sampling and experimental analyses were designed to primarily test if the Sicilian Channel can be considered as effective eco-physiological barrier for Mediterranean demersal sympatric elasmobranchs.MethodsThe phylogeography and the historical demography of target species were inferred by analysing the nucleotide variation of three mitochondrial DNA markers (i.e., partial sequence of COI, NADH2 and CR) obtained from a total of 248 individuals sampled in the Western and Eastern Mediterranean Sea as well as in the adjacent northeastern Atlantic Ocean. Phylogeographic analysis was performed by haplotype networking and testing spatial genetic differentiation of samples (i.e., analysis of molecular variance and of principal components). Demographic history of Mediterranean populations was reconstructed using mismatch distribution and Bayesian Skyline Plot analyses.ResultsNo spatial genetic differentiation was identified in either catshark species, while phylogeographic structure of lineages was identified in both skates, withR. miraletusmore structured thanR. clavata. However, such structuring of skate lineages was not consistent with the separation between Western and Eastern Mediterranean. Sudden demographic expansions occurred synchronously during the upper Pleistocene (40,000–60,000 years ago) in both skates andG. melastomus, likely related to optimal environmental conditions. In contrast,S. caniculaexperienced a slow and constant increase in population size over the last 350,000 years.DiscussionThe comparative analysis of phylogeographic and historical demographic patterns for the Mediterranean populations of these elasmobranchs reveals that historical phylogeographic breaks have not had a large impact on their microevolution. We hypothesize that interactions between environmental and ecological/physiological traits may have been the driving force in the microevolution of these demersal elasmobranch species in the Mediterranean rather than oceanographic barriers.