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Gonçalves Jardim de Freitas Araujo, Teresa Mafalda
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- Pleistocene expansion, anthropogenic pressure and ocean currents: Disentangling the past and ongoing evolutionary history of Patella aspera Röding, 1798 in the archipelago of MadeiraPublication . Sousa, Ricardo; Vasconcelos, Joana; Vera-Escalona, Iván; Pinto, Ana Rita; Hawkins, S. J.; Freitas, Mafalda; Delgado, João; González, José A.; Riera, RodrigoAims: Rising sea-level following the Last Glacial Maximum lead to fragmentation of coastal limpet populations between islands of the Archipelago of Madeira. This fragmentation is reinforced by recent heavy exploitation reducing effective population size on Madeira Island. We use the limpet P. aspera to understand how the role of processes at different time scales (i.e. changes in the sea level and overexploitation) can influence the genetic composition of an extant species, relating these processes to reproductive phenology and seasonal shifts in ocean currents. Location: Madeira Island, Porto Santo and Desertas (Archipelago of Madeira, NE Atlantic Ocean). Taxon: The limpet Patella aspera. Methods: Twelve microsatellite genetic markers were used. A power analysis was used to evaluate the power of the microsatellite markers to detect a signal of population differentiation. Long-term past migrations were assessed using a Bayesian Markov Montecarlo approach in the software MIGRATE-n to estimate mutation-scaled migration rates (M = m/μ; m, probability of a lineage immigrating per generation; μ, mutation rate). Two sce narios were evaluated using an Approximate Bayesian Computation (ABC) in the software DIYABC 2.1 (i) Sce nario 1: considered a population scenario from a reduced Ne at time t3 to a higher Ne at time t2; and (ii) Scenario 2 considering a reduction of Ne from a time t3 to a time t2. Results: Colonization of the archipelago by Portuguese settlers six centuries ago probably led to an important decrease in the genetic diversity of the species (Ne). Contemporary gene flow strongly support a pattern of high asymmetric connectivity explained by the reproductive phenology of the species and spatio-temporal seasonal changes in the ocean currents. Spatio-temporal reconstructions using Bayesian methods, including coalescent and Approximate Bayesian Computation (ABC) approaches, suggest changes in the migration patterns from highly symmetric to highly asymmetric connectivity with subtle population differentiation as consequence of post-glacial maximum sea level rise during the Holocene.
- Deep Sea Chondrichthyes from Madeira and Nearby Seamounts (NE Atlantic)Publication . Araujo, Teresa Mafalda Gonçalves Jardim de Freitas; Kaufmann, Manfred JosefChondrichthyes play a key role in the ecological balance of the ecosystems as predatory species. However, more than one-third of these species are threatened by overfishing. The lack of information on chondrichthyan species in the archipelago of Madeira led to this study, which intended to provide reliable information on their taxonomy, biology, population dynamics and fisheries. An updated checklist of cartilaginous fishes, new records, taxonomic annotations, and clarification as well filling the gaps on life history of several species were accomplished during this thesis. The checklist confirmed the presence of 67 species of sharks, rays, and chimaeras. Another 14 species previously referred for the area are now considered dubious records, and 5 species are withdrawn from the list. Centrophorus uyato is here recorded for the first time from Madeira. Of the species reported 24 are in the list of threatened species according to the IUCN European Red List of marine fishes. Hydrolagus affinis and Chimaera opalescens are also first recorded for the Madeira region, and their known range of distribution are extended. The clarification and resolution of uncertainties over the identification of Deania calcea and Deania hystricosa were accomplished through morphological and molecular studies, that confirm that both are the same species. The knowledge of fish diversity of several seamounts belonging to Madeira-Tore complex at different depth strata down to 2500 m was increased, bridging the information gap regarding seamount associated elasmobranchs. The checklist of cartilaginous fish species for Seine and Unicorn seamounts confirmed the presence of 17 species in Seine and 11 in Unicorn, corresponding to about 31% of the valid Chondrichthyes reported for the archipelago of Madeira. The work herein presented contributed to increase the knowledge of fish communities, diversity, and occurrence of Chondrichthyes in the archipelago of Madeira. A reliable overview of Madeira’s elasmobranch fisheries and their evolution, between 1990 and 2020, is also provided. The study on the biology and population dynamics of Centrophorus squamosus allowed to verify that the pressure of fishing did not cause critical changes in the life history parameters of the species over 22 years. The information obtained is essential to obtain the geographic distribution and depth of the species, as well asto evaluate the fisheries impact on the biology and population dynamics of this group, aiming to contribute to the development of suitable management strategies to preserve these species, specifically the populations under pressure by the Madeiran longline artisanal fishery.
- Major ocean currents may shape the microbiome of the topshell Phorcus sauciatus in the NE Atlantic OceanPublication . Sousa, Ricardo; Vasconcelos, Joana; Vera-Escalona, Iván; Delgado, João; Freitas, Mafalda; González, José A.; Riera, RodrigoStudies on microbial communities are pivotal to understand the role and the evolutionary paths of the host and their associated microorganisms in the ecosystems. Meta-genomics techniques have proven to be one of the most efective tools in the identifcation of endosymbiotic communities of host species. The microbiome of the highly exploited topshell Phorcus sauciatus was characterized in the Northeastern Atlantic (Portugal, Madeira, Selvagens, Canaries and Azores). Alpha diversity analysis based on observed OTUs showed signifcant diferences among regions. The Principal Coordinates Analysis of beta-diversity based on presence/absence showed three well diferentiated groups, one from Azores, a second from Madeira and the third one for mainland Portugal, Selvagens and the Canaries. The microbiome results may be mainly explained by large-scale oceanographic processes of the study region, i.e., the North Atlantic Subtropical Gyre, and specifcally by the Canary Current. Our results suggest the feasibility of microbiome as a model study to unravel biogeographic and evolutionary processes in marine species with high dispersive potential.