Suchergebnisse

Este artículo contiene 14 páginas, 6 figuras, 2 tablas. ; Connectivity and local adaptation are two contrasting evolutionary forces highly infuencing population structure. To evaluate the impact of early-life traits and environmental conditions on genetic structuring and adaptation, we studied two sympatric fsh species in the Western Mediterranean Sea: Symphodus tinca and S. ocellatus. We followed an individual-based approach and measured early-life history traits from otolith readings, gathered information on environmental variables and obtained genome-wide markers from genotyping-by-sequencing (GBS). The two species presented contrasting population structure across the same geographic gradient, with high and signifcant population diferentiation in S. ocellatus, mostly determined by oceanographic fronts, and low diferentiation and no front efect in S. tinca. Despite their diferent levels of genetic diferentiation, we identifed in both species candidate regions for local adaptation by combining outlier analysis with environmental and phenotypic association analyses. Most candidate loci were associated to temperature and productivity in S. ocellatus and to temperature and turbulence in S. tinca suggesting that diferent drivers may determine genomic diversity and diferentiation in each species. Globally, our study highlights that individual-based approach combining genomic, environmental and phenotypic information is key to identify signals of selection and the processes mediating them. ; Tis work was supported by the Spanish Government projects 'ChallenGen' (CTM2013-48163) and 'PopCOmics' (CTM2017-88080) (MCIU, AEI/FEDER, UE) and by the European FP7 CoCoNet project (Ocean 2011-4, Grant Agreement #287844). Te authors CC and MP are members of the research group SGR2017-1120 and EM of SGR2017-378 (Catalan Government). HT was supported by a PhD scholarship funded by the Spanish Ministry of Science, Innovation and Universities (FPU15/02390). ; Peer reviewed

Este artículo contiene 14 páginas, 7 figuras, 2 tablas. ; Global environmental changes may have a profound impact on ecosystems. In this context, it is crucial to gather biological and ecological information of the main species in marine communities to predict and mitigate potential effects of shifts in their distribution, abundance, and interactions. Using genotyping by sequencing (GBS), we assessed the genetic structure of a keystone species in the Mediterranean shallow littoral ecosystems, the black sea urchin Arbacia lixula. This bioengineer species can shape their communities due to its grazing activity and it is experiencing an ongoing expansion with increasing temperatures. The population genomic analyses on 5,241 loci sequenced in 240 individuals from 11 Mediterranean sampled populations revealed that all populations were diverse and showed significant departure from equilibrium. Albeit genetic differentiation was in general shallow, a significant break separated the western and eastern Mediterranean populations, a break not detected in previous studies with less resolutive markers. Notably, no clear effect of the Almería-Oran front, an important break in the Atlanto-Mediterranean transition, could be detected among the western basin populations, where only a slight differentiation of the two northernmost populations was found. Despite the generally low levels of genetic differentiation found, we identified candidate regions for local adaptation by combining different genomic analysis with environmental data. Salinity, rather than temperature, seemed to be an important driver of genetic structure in A. lixula. Overall, from a population genomics standpoint, there is ample scope for A. lixula to continue thriving and adapting in the warming Mediterranean. ; This research was funded by projects PopCOmics (CTM2017- 88080, funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe" of the European Union) and MarGeCh (PID2020-118550RB, funded by MCIN/AEI/10.13039/501100011033) from the Spanish Government. This is a contribution from the Consolidated Research Group "Benthic Biology and Ecology" SGR2017-1120 (Catalan Government). Some localities were sampled under the European FP7 CoCoNet project (Ocean 2011-4, Grant Agreement #287844). ; Peer reviewed

Este artículo contiene 17 páginas, 6 figuras, 2 tablas. ; Aim: The Atlanto-Mediterranean edible purple sea urchin, Paracentrotus lividus, is a commercially exploited keystone species in benthic communities. Its browsing activity can deeply modify the littoral landscape, and changes in its abundance are of major conservation concern. This species is facing nowadays contrasting anthropogenic pressures linked to predator release, exploitation and sea warming. Management of this key species requires knowledge of its genetic structure, connectivity and local adaptation. Our goal was to assess the current global status of the species under a genomic perspective. Location: Atlanto-Mediterranean shores from Morocco and France to Turkey. Methods: We used genotyping by sequencing (GBS) of 241 individuals belonging to 11 populations spanning the known range of distribution of the species. We obtained 3,348 loci for population genomics and outlier analyses. Results: We identified significant genetic structure and a gradient matching the longitudinal position of the localities. A hierarchical analysis revealed two main clusters (Atlantic and Mediterranean) and subtler patterns of differentiation within them. Candidate markers for selection identified between and within these two main clusters were mostly different, likely indicating different selective pressures. Adaptation to maximum salinity and maximum temperature appeared as an important driver of the transition between Atlantic and Mediterranean basins. Other stressors, such as minimum temperature or range of temperature, seem to define the structuring within the Mediterranean. Main conclusions: Our study shows the potential of hierarchical analyses on population genomics to detect fine-scale genetic structure and adaptation signatures in marine species with long dispersal capabilities. Although genetic interchange occurs widely in Paracentrotus lividus, the species is sensitive to dispersal barriers, displays isolation by distance and faces local selective pressures associated to environmental conditions, all of which can render it more vulnerable than previously thought. ; This work was supported by the Spanish Government projects ChallenGen CTM2013-48163 and PopCOmics CTM2017-88080 (MCIU, AEI/FEDER, UE). This is a contribution from the Consolidated Research Group "Benthic Biology and Ecology" SGR2017-1120 (Catalan Government). ; Peer reviewed

The available information regarding the 2 sea turtle species breeding in the Mediterranean (loggerhead turtle Caretta caretta and green turtle Chelonia mydas) is reviewed, including biometrics and morphology, identification of breeding and foraging areas, ecology and behaviour, abundance and trends, population structure and dynamics, anthropogenic threats and conservation measures. Although a large body of knowledge has been generated, research efforts have been inconsistently allocated across geographic areas, species and topics. Significant gaps still exist, ranging from the most fundamental aspects, such as the distribution of major nesting sites and the total number of clutches laid annually in the region, to more specific topics like age at maturity, survival rates and behavioural ecology, especially for certain areas (e.g. south-eastern Mediterranean). These gaps are particularly marked for the green turtle. The recent positive trends of nest counts at some nesting sites may be the result of the cessation of past exploitation and decades of conservation measures on land, both in the form of national regulations and of continued active protection of clutches. Therefore, the current status should be considered as dependent on such ongoing conservation efforts. Mitigation of incidental catch in fisheries, the main anthropogenic threat at sea, is still in its infancy. From the analysis of the present status a comprehensive list of re search and conservation priorities is proposed. ; C.C. is supported by the project CTM2013-48163 of the Spanish Ministry of Economy and Competitivity. The Cyprus Wildlife Society (CWS) acknowledges the financial support of the Department of Fisheries and Marine Research of the Government to the CWS for the implementation of the Turtle Conservation Project in the period 2010−2016 and for all its assistance to the Society in previous years. J.T. is supported by project Prometeo II (2015-018) of the Generalitat Valenciana and projects MEDSEALITTER-INTERREG and INDICIT of the European Union. ; Peer Reviewed