No abstract

Oceanic islands are recognized evolutionary hotspots for terrestrial organisms, but little is known about their impact on marine organisms' evolution and biogeography. The volcanic archipelagos of Macaronesia occupy a vast and complex region which is particularly suitable to investigate marine island biogeography.In this study, we used mitochondrial DNA sequences to investigate the genetic diferentiation between the populations from Webbnesia (i.e. Madeira, Selvagens and Canaries) and adjacent coasts, of 23 intertidal peracarid species. All species had unexpectedly high intraspecific genetic distances, reaching more than 20% in some cases. Between 79 and 95 Molecular Operational Taxonomic Units (MOTUs) were found in these species. Webbnesia populations displayed an impressive genetic diversity and high endemicity, with 83% of the MOTUs being private to these islands, particularly La Palma and Madeira. Network analyses suggested higher similarity between Webbnesia and Azores than with adjacent continental coasts.These results reveal an unanticipated and sweeping biogeographic discontinuity of peracaridean fauna between Webbnesia and the Iberian Peninsula, raising suspicion about the possible occurrence of identical patterns in other groups of marine invertebrates in the region. We emphasize the unique genetic heritage hosted by these islands, underlining the need to consider the fine scale endemicity in marine conservation efforts.

Oceanic islands are recognized evolutionary hotspots for terrestrial organisms, but little is known about their impact on marine organisms' evolution and biogeography. The volcanic archipelagos of Macaronesia occupy a vast and complex region which is particularly suitable to investigate marine island biogeography. In this study, we used mitochondrial DNA sequences to investigate the genetic diferentiation between the populations from Webbnesia (i.e. Madeira, Selvagens and Canaries) and adjacent coasts, of 23 intertidal peracarid species. All species had unexpectedly high intraspecific genetic distances, reaching more than 20% in some cases. Between 79 and 95 Molecular Operational Taxonomic Units (MOTUs) were found in these species. Webbnesia populations displayed an impressive genetic diversity and high endemicity, with 83% of the MOTUs being private to these islands, particularly La Palma and Madeira. Network analyses suggested higher similarity between Webbnesia and Azores than with adjacent continental coasts. These results reveal an unanticipated and sweeping biogeographic discontinuity of peracaridean fauna between Webbnesia and the Iberian Peninsula, raising suspicion about the possible occurrence of identical patterns in other groups of marine invertebrates in the region. We emphasize the unique genetic heritage hosted by these islands, underlining the need to consider the fine scale endemicity in marine conservation efforts.

The application of nanoparticles (NPs) in consumer products has been increasing over the past few years. Their release into the environment is likely to happen at any stage of production or during the use of products containing NPs. Zinc oxide NPs (ZnO-NP) are among the most-used NPs on the market due to its intrinsic properties, such as ultraviolet (UV) absorption. The aim of the present study was to assess the combined effects of ZnO-NP and UV radiation on 2 freshwater species: Daphnia magna and Danio rerio. The initial hypothesis was that the presence of ZnO-NP in the aquatic media would decrease the damaging effects of UV radiation for both species. The endpoints assessed for D. magna were immobilization, feeding inhibition, and reproduction output. For D. rerio, egg development was studied during 96 h and mortality, hatching delay, and abnormal development were the endpoints recorded. Combined exposures were designed based on the single toxicity of both stressors and analyzed based on the independent action concept and exploring possible deviations for synergism/antagonism, dose level, and dose ratio. Combined exposures with D. magna induced synergism on reproduction, decreasing the number of neonates produced more than expected based on both stressors' individual toxicity. Single exposures of D. rerio embryos to both stressors induced negative effects. The combined exposures caused a dose-ratio deviation pattern on mortality and hatching, with a synergism observed when ZnO-NP was the dominant stressor, changing to antagonism when UV radiation dominated the combined exposure. Regarding the results attained, studying ZnO toxicity under laboratory conditions may underestimate the risks when considering the potential interaction on effects when combined with UV radiation.