River regulation for hydroelectricity production results in rapid changes of flow and habitat features, but its effects in the movement patterns of freshwater fish are not well understood. Radiotelemetry was used to track Iberian barbel during a year cycle in non-regulated and regulated rivers. We applied a kernel density method to estimate and compare home range sizes of the two populations. Seasonal patterns of movement and the intra-annual variation in habitat preferences were also compared. Barbel inhabiting regulated river exhibit larger and more continuous home and core ranges, in opposition to the smaller and patchy areas used by fish inhabiting the non-regulated river. Seasonal movements of both populations were differentiated by the drought period. Barbel from the non-regulated river had to search for suitable refuges, with specific habitat characteristics, in which they remained aggregated during harsh summer conditions. Conversely, barbel from regulated river kept a continuous distribution along the river. This study contributes to the management of regulated rivers by providing insights about which flow components are more altered by hydropeaking operations and which are the most critical annual periods for fish movements. It also suggests several restoration actions, such as the protection of fish summer refuges, the restoration of large-scale temporal streamflow variability and the reduction of daily rates of discharge rise and fall, which should be continuously monitored in order to increase their efficiency and provide new knowledge.

The natural 15N/14N isotope composition (δ15N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ15N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol−1), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency—WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ15N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol−1 [CO2] and WD conditions. In summary, leaf δ15N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions.

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Aim We aim to determine the relative influence of climate and species interactions on the global distribution of Soricinae and Crocidurinae shrews through the analysis of their distribution, climate niche and evolutionary history. Both subfamilies are partially allopatric in Eurasia, but in North America only Soricinae is present, thus providing a scenario to address the role of potential competition versus competitive release in determining species’ realized distributions at a global scale. Location Global. Taxon Soricidae, Eulipotyphla. Methods We obtained climate data from WorldClim, spatial range data for 302 species from the IUCN Red List and 2614 cytb complete sequences from GenBank. We modelled the potential distribution of the subfamilies by computing three environmental niche models using Maxent: one for Crocidurinae, one for American Soricinae and one for Afro‐Eurasian Soricinae. We created matrices for the genetic, spatial and climatic distance between all pairs of species to calculate the average climatic distance between pairs of species within and between subfamilies. We then evaluated this distance against a null model. To assess the effect of phylogeny on the segregation of the subfamilies, we checked for correlation between genetic and spatial distance. Results The Afro‐Eurasian Soricinae environmental niche model under‐predicted its occurrence in America. The average climatic distance between subfamilies was larger than expected by chance, while the distance within both Crocidurinae and Afro‐Eurasian Soricinae was smaller. The average distance between the American and Afro‐Eurasian Soricinae was also larger than expected. There was no correlation between spatial and genetic distance for genetic distances over 0.14 substitutions per nucleotide site. Main conclusions Climate significantly influences the distribution of both subfamilies. As expected in a scenario of competitive release, the climatic range of the Soricinae in America is larger than in Afro‐Eurasia. Thus, besides climate, competition may play an important role in shaping species’ global distributions.