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Estee artículo contiene 24 páginas, 4 tablas, 8 figuras. ; Among the complex ecosystems and habitats that form the deep sea, submarine canyons and open slope systems are regarded as potential hotspots of biodiversity. We assessed the spatial and temporal patterns of biodiversity in sediment communities of a NW Mediterranean Canyon and its adjacent open slope (Blanes Canyon) with DNA metabarcoding. We sampled three layers of sediment and four different depths (900–1750 m) at two seasons, and used a fragment of the mitochondrial gene cytochrome c oxidase subunit I (COI) as a metabarcoding marker. The final dataset contained a total of 15,318 molecular operational taxonomic units (MOTUs). Metazoa, Stramenopiles and Archaeplastida were the dominant taxa and, within metazoans, Arthropoda, Nematoda and Cnidaria were the most diverse. There was a trend towards decreasing MOTU richness and diversity in the first few cm (1 to 5) of the sediment, with only 26.3% of the MOTUs shared across sediment layers. Our results show the presence of heterogeneous communities in the studied area, which was significantly different between zones, depths and seasons. We compared our results with the ones presented in a previous study, obtained using the v7 region of the 18S rRNA gene in the same samples. There were remarkable differences in the total number of MOTUs and in the most diverse taxa. COI recovered a higher number of MOTUs, but more remained unassigned taxonomically. However, the broad spatio-temporal patterns elucidated from both datasets coincided, with both markers retrieving the same ecological information. Our results showed that COI can be used to accurately characterize the studied communities and constitute a high-resolution method to detect ecological shifts. We also highlight that COI reference databases for deep-sea organisms have important gaps, and their completeness is essential in order to successfully apply metabarcoding techniques. ; The sampling has been done in the framework of the DOSMARES project (CTM2010-21810) of the Spanish Government. This research has been funded by project PopCOmics CTM2017-88080 (MCIU/AEI/FEDER, UE) of the Spanish Government. This is a contribution from the Consolidated Research Group "Benthic Biology and Ecology" SGR2017-1120 of the Catalan Government. ; Peer reviewed

30 páginas, 9 figuras, 1 tabla. ; We assessed spatio-temporal patterns of diversity in deep-sea sediment communities using metabarcoding. We chose a recently developed eukaryotic marker based on the v7 region of the 18S rRNA gene. Our study was performed in a submarine canyon and its adjacent slope in the Northwestern Mediterranean Sea, sampled along a depth gradient at two different seasons. We found a total of 5,569 molecular operational taxonomic units (MOTUs), dominated by Metazoa, Alveolata and Rhizaria. Among metazoans, Nematoda, Arthropoda and Annelida were the most diverse. We found a marked heterogeneity at all scales, with important differences between layers of sediment and significant changes in community composition with zone (canyon vs slope), depth, and season. We compared the information obtained from metabarcoding DNA and RNA and found more total MOTUs and more MOTUs per sample with DNA (ca. 20% and 40% increase, respectively). Both datasets showed overall similar spatial trends, but most groups had higher MOTU richness with the DNA template, while others, such as nematodes, were more diverse in the RNA dataset. We provide metabarcoding protocols and guidelines for biomonitoring of these key communities in order to generate information applicable to management efforts. ; The sampling was done in the framework of the DOSMARES project (CTM2010-21810) of the Spanish Government. MG benefitted from a FPI predoctoral contract of the Spanish Government. This research was funded by project CHALLENGEN CTM2013-48163 of the Spanish Government. ; Peer reviewed

Peer reviewed ; We assessed spatio-temporal patterns of diversity in deep-sea sediment communities using metabarcoding. We chose a recently developed eukaryotic marker based on the v7 region of the 18S rRNA gene. Our study was performed in a submarine canyon and its adjacent slope in the Northwestern Mediterranean Sea, sampled along a depth gradient at two different seasons. We found a total of 5,569 molecular operational taxonomic units (MOTUs), dominated by Metazoa, Alveolata and Rhizaria. Among metazoans, Nematoda, Arthropoda and Annelida were the most diverse. We found a marked heterogeneity at all scales, with important differences between layers of sediment and significant changes in community composition with zone (canyon vs slope), depth, and season. We compared the information obtained from metabarcoding DNA and RNA and found more total MOTUs and more MOTUs per sample with DNA (ca. 20% and 40% increase, respectively). Both datasets showed overall similar spatial trends, but most groups had higher MOTU richness with the DNA template, while others, such as nematodes, were more diverse in the RNA dataset. We provide metabarcoding protocols and guidelines for biomonitoring of these key communities in order to generate information applicable to management efforts. The sampling was done in the framework of the DOSMARES project (CTM2010-21810) of the Spanish Government. MG benefitted from a FPI predoctoral contract of the Spanish Government. This research was funded by project CHALLENGEN CTM2013-48163 of the Spanish Government. ; 30 páginas, 9 figuras, 1 tabla.

26 páginas, 8 figuras, 2 tablas ; Marine sediments are home to one of the richest species pools on Earth, but logistics and a dearth of taxonomic work-force hinders the knowledge of their biodiversity. We characterized α- and β-diversity of deep-sea assemblages from submarine canyons in the western Mediterranean using an environmental DNA metabarcoding. We used a new primer set targeting a short eukaryotic 18S sequence (ca. 110 bp). We applied a protocol designed to obtain extractions enriched in extracellular DNA from replicated sediment corers. With this strategy we captured information from DNA (local or deposited from the water column) that persists adsorbed to inorganic particles and buffered short-term spatial and temporal heterogeneity. We analysed replicated samples from 20 localities including 2 deep-sea canyons, 1 shallower canal, and two open slopes (depth range 100–2,250 m). We identified 1,629 MOTUs, among which the dominant groups were Metazoa (with representatives of 19 phyla), Alveolata, Stramenopiles, and Rhizaria. There was a marked small-scale heterogeneity as shown by differences in replicates within corers and within localities. The spatial variability between canyons was significant, as was the depth component in one of the canyons where it was tested. Likewise, the composition of the first layer (1 cm) of sediment was significantly different from deeper layers. We found that qualitative (presence-absence) and quantitative (relative number of reads) data showed consistent trends of differentiation between samples and geographic areas. The subset of exclusively benthic MOTUs showed similar patterns of β-diversity and community structure as the whole dataset. Separate analyses of the main metazoan phyla (in number of MOTUs) showed some differences in distribution attributable to different lifestyles. Our results highlight the differentiation that can be found even between geographically close assemblages, and sets the ground for future monitoring and conservation efforts on these bottoms of ecological and economic importance. ; The sampling has been done in the framework of the INDEMARES project (LIFE+ NAT/E/ 000732) of the European Union and the DOSMARES project (CTM2010-21810) of the Spanish Government. A European Science Foundation ConGenOmics Exchange Grant (n 3919) funded MG stay at the LECA lab. This research has been funded by projects BENTHOMICS CTM2010-22218 and CHALLENGEN CTM2013-48163 of the Spanish ; Peer reviewed

12 páginas, 4 figuras, 6 tablas. ; Arbacia lixula and Paracentrotus lividus are the dominant sea urchins in the Mediterranean sublittoral, where they are key structuring species due to their grazing activity. It has been commonly accepted that competition between both species is minimized by specializing in different algal foods: A. lixula is considered to feed mainly on encrusting coralline algae, while P. lividus prefers fleshy macroalgae. We used stable isotope analysis to test if these species occupy different trophic positions at three western Mediterranean and one Macaronesian locations. Our results unambiguously show that A. lixula always occupies a higher trophic level than P. lividus, with a δ15N comparable in some locations to strict carnivores such as Actinia schmidti or Marthasterias glacialis. A temporal monitoring at one locality showed that this signature of a higher trophic level is consistent throughout the year. These results are incompatible with the current belief of an herbivorous diet for A. lixula and suggest that it must be considered an omnivore tending to carnivory in Mediterranean ecosystems, feeding at least partially on sessile animals such as Cirripedia, Hydrozoa or Bryozoa. A parallel analysis of gut contents showed a predominance of vegetal items in both species, although A. lixula consistently had a higher abundance of animal components than P. lividus. Our results challenge the validity of using gut content observations alone for characterizing the trophic behaviour of omnivorous marine invertebrates that feed on a variety of food sources with different digestibility. ; This work has been funded by the projects CTM2007-66635, CTM2010-22218 from the Spanish Government, and the project BIOCON 08-187/09 from BBVA Foundation. ; 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 16 páginas, 4 figuras, 4 tablas. ; The genetic structure of 13 populations of the amphiatlantic sea urchin Arbacia lixula, as well as temporal genetic changes in three of these localities, were assessed using ten hypervariable microsatellite loci. This thermophilous sea urchin is an important engineer species triggering the formation of barren grounds through its grazing activity. Its abundance seems to be increasing in most parts of the Mediterranean, probably favoured by warming conditions. Significant genetic differentiation was found both spatially and temporally. The main break corresponded to the separation of western Atlantic populations from those in eastern Atlantic and the Mediterranean Sea. A less marked, but significant differentiation was also found between Macaronesia (eastern Atlantic) and the Mediterranean. In the latter area, a signal of differentiation between the transitional area (Alboran Sea) and the rest of the Mediterranean was detected. However, no genetic structure is found within the Mediterranean (excluding Alboran) across the Siculo-Tunisian Strait, resulting from either enough gene flow to homogenize distance areas or/and a recent evolutionary history marked by demographic expansion in this basin. Genetic temporal variation at the Alboran Sea is as important as spatial variation, suggesting that temporal changes in hydrological features can affect the genetic composition of the populations. A picture of genetic homogeneity in the Mediterranean emerges, implying that the potential expansion of this keystone species will not be limited by intraspecific genetic features and/or potential impact of postulated barriers to gene flow in the region. ; This research was financially supported by the Spanish Government projects CTM2013-48163 and CTM2017-88080 (AEI, FEDER-UE) and by a "Juan de la Cierva" contract from the Spanish Government to RPP. ; 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

American black bears are considered dependent on high‐elevation forests or other montane habitats in the drylands of western North America. Black bear sign, including that of cubs, was observed throughout the summers of 2015, 2016, and 2018 along a perennial desert river in the Sonoran Desert of Arizona. We analyzed the contents of 21 black bear scats, collected from May to October of 2016 and 2018. Apache cicada nymphs (Diceroprocta apache) were the dominant food item, occurring in 90% of scats and comprising an average of 59% of scat contents. In the process of excavating these nymphs, bears created large areas of turned‐over soil, a form of ecosystem engineering with potential implications for soils, vegetation, and fluvial geomorphology. Given that species distributions are shaped by physiological and ecological contexts, as well as anthropogenic legacies, it is possible that black bears once occurred more commonly in desert riparian systems prior to widespread agricultural development, hunting, and dewatering. Although more research is necessary, we suggest that desert riparian systems may be an alternative habitat for black bears. Better understanding the diet and habitat breadth of American black bears is important in the context of increasing landscape fragmentation and militarization in the U.S.‐Mexican borderlands.

American black bears are considered dependent on high-elevation forests or other montane habitats in the drylands of western North America. Black bear sign, including that of cubs, was observed throughout the summers of 2015, 2016, and 2018 along a perennial desert river in the Sonoran Desert of Arizona. We analyzed the contents of 21 black bear scats, collected from May to October of 2016 and 2018. Apache cicada nymphs (Diceroprocta apache) were the dominant food item, occurring in 90% of scats and comprising an average of 59% of scat contents. In the process of excavating these nymphs, bears created large areas of turned-over soil, a form of ecosystem engineering with potential implications for soils, vegetation, and fluvial geomorphology. Given that species distributions are shaped by physiological and ecological contexts, as well as anthropogenic legacies, it is possible that black bears once occurred more commonly in desert riparian systems prior to widespread agricultural development, hunting, and dewatering. Although more research is necessary, we suggest that desert riparian systems may be an alternative habitat for black bears. Better understanding the diet and habitat breadth of American black bears is important in the context of increasing landscape fragmentation and militarization in the U.S.-Mexican borderlands.

American black bears are considered dependent on high-elevation forests or other montane habitats in the drylands of western North America. Black bear sign, including that of cubs, was observed throughout the summers of 2015, 2016, and 2018 along a perennial desert river in the Sonoran Desert of Arizona. We analyzed the contents of 21 black bear scats, collected from May to October of 2016 and 2018. Apache cicada nymphs (Diceroprocta apache) were the dominant food item, occurring in 90% of scats and comprising an average of 59% of scat contents. In the process of excavating these nymphs, bears created large areas of turned-over soil, a form of ecosystem engineering with potential implications for soils, vegetation, and fluvial geomorphology. Given that species distributions are shaped by physiological and ecological contexts, as well as anthropogenic legacies, it is possible that black bears once occurred more commonly in desert riparian systems prior to widespread agricultural development, hunting, and dewatering. Although more research is necessary, we suggest that desert riparian systems may be an alternative habitat for black bears. Better understanding the diet and habitat breadth of American black bears is important in the context of increasing landscape fragmentation and militarization in the U.S.-Mexican borderlands.

19 páginas, 6 figuras, 2 tablas. ; Leaf elemental and secondary metabolite contents and morphological traits are important measures of time-dependent ecosystem changes. We aimed to test whether plants from older tropical forests have lower nutrient contents and different elemental stoichiometry than plants from younger ecosystems (''soil age'' hypothesis) and whether they had different contents of carbon based secondary compounds (CBSC) and morphological traits as a result of a longer evolution under tropical conditions. We conducted a phylogeny-independent study of the foliar chemical and structural traits in two sets of 86 species each measured in two different-aged tropical forests, a young soil forest in Hawaii and an old soil forest in Borneo. The leaf contents of nutrients and micronutrients tended to be higher in Hawaii than in Borneo but leaf N:P content ratio was not different. The ''soil age'' hypothesis was thus only partially supported by the results indicating that several other factors influence plant elemental content. Total phenolic content was twice larger in Hawaiian than in Bornean plant species. Terpene contents were not different in terpene-containing species but the percentage of species containing terpenes was much higher in Borneo (97%) than in Hawaii (34%) suggesting that the longer time of evolution in Borneo has allowed a more widespread development of very diverse defensive, allelopatic and information relationships of plants with specialist herbivores and other plants. Principal component analyses separated Hawaii and Borneo species on the basis of leaf elemental composition, total phenolics and terpene contents and leaf dry mass per area (LMA). The results collectively support the ''leaf economic spectrum'' and ''carbon excess'' paradigms because in both sets of species and also in the combined set of Borneo and Hawaiian species, there are negative relationships of N content with LMA and total phenolics. The results suggest thus that changes throughout time in N and P availability can be important but do not explain all the variability underlying the evolutionary changes in leaf chemistry and structure in these tropical forests. Other factors determining species biogeochemical niche such as K, Mg or S elemental stoichiometry, leaf economic traits and changes in plant defence and communication strategy are also likely to be involved. ; This research was supported by the Spanish Government projects CGL2006-04025/BOS, CGL2010- 17172, Consolider Ingenio Montes (CSD2008-00040), by the Catalan Government project SGR 2009-458 and by the Estonian Ministry of Education and Research (grant SF1090065s07) ; Peer reviewed

12 páginas, 4 tablas, 2 figuras. ; Aim Alien plant invasion is prominent in the Hawaiian Islands. There are many factors involved in invader success. To date, there is a general lack of information about one of them, which we aim to study here: the terpene emission capacity of both Hawaiian native and alien plants. Location Oahu (Hawaii). Methods We screened 35 alien and 35 native dominant plant species on Oahu Island for monoterpene emissions. The emission rates were measured from field-grown plants under standardized conditions of temperature and quantum flux density in the laboratory. Results The emission rates of total terpenes ranged from 0 µg g−1 h−1 to 55 µg g−1 h−1, and altogether 15 different terpenes were emitted in detectable amounts by the overall set of species. A phylogenetic signal was observed for total terpene emissions. Total terpene emission rates were higher in aliens than in native species (12.8 ± 2.0 vs. 7.6 ± 1.9 µg g−1 h−1, respectively). Main conclusions The greater terpene emission capacity may confer protection against multiple stresses and may partly account for the success of the invasive species, and may make invasive species more competitive in response to new global change-driven combined stresses. These results are consistent with aliens coming from very diverse ecosystems with generally higher biotic and abiotic stress pressures, and having higher nutrient concentrations. On the contrary, these results are not consistent with the 'excess carbon' hypotheses. These results indicate changes in vegetation terpene emissions brought about by alien plant invasions. ; This study was supported by the University of Hawai'i (G. P. Wilder research funds) and the grants from the Spanish Government (CGL2006-04025/BOS and Consolider-Ingenio Montes CSD 2008-00040), the Catalan Government (SGR 2009- 458), the Spanish National Research Council (CSIC-PIF08-006- 3), the Estonian Science Foundation (grant 7645), and the Estonian Ministry of Education and Science (SF1090065s07). ; Peer reviewed

17 páginas, 3 figuras, 4 tablas, 1 apéndice. ; Capacity for terpene production may confer advantage in protection against abiotic stresses such as heat and drought, and also against herbivore and pathogen attack. Plant invasive success has been intense in the Hawaiian islands, but little is known about terpene content in native and alien plant species on these islands. We conducted a screening of leaf terpene concentrations in 35 native and 38 alien dominant plant species on Oahu island. Ten (29%) of the 35 native species and 15 (39%) of the 38 alien species contained terpenes in the leaves. This is the first report of terpene content for the ten native species, and for 10 of the 15 alien species. A total of 156 different terpenes (54 monoterpenes and 102 sesquiterpenes) were detected. Terpene content had no phylogenetic significance among the studied species. Alien species contained significantly more terpenes in leaves (average ± SE=1965±367 μg g −1 ) than native species (830±227 μg g −1 ). Alien species showed significantly higher photosynthetic capacity, N content, and lower Leaf Mass Area (LMA) than native species, and showed higher total terpene leaf content per N and P leaf content. Alien species, thus, did not follow the expected pattern of "excess carbon" in comparison with native species. Instead, patterns were consistent with the "nutrient driven synthesis" hypothesis. Comparing alien and native species, the results also support the modified Evolution of Increased Competitive Ability (EICA) hypothesis that suggests that alien success may be favored by a defense system based on an increase in concentrations of less costly defenses (terpenes) against generalist herbivores. ; This research was supported by grants from the Spanish Government (CGL2006-04025/BOS and Consolider-Ingenio Montes CSD 2008-00040), the Catalan Government (SGR 2009-458), Estonian Science Foundation (grant 7645), and the Estonian Ministry of Education and Science (SF1090065s07) ; Peer reviewed