Oceanic currents maintain the genetic structure of non-marine coastal taxa in the western Mediterranean Sea.

Coastal habitats are amongst the most dynamic on Earth, due to their simultaneous exposure to terrestrial, oceanic and atmospheric processes. Coastal taxa are therefore often ecologically specialised and adapted to withstand frequent shifts in sea level, wave exposure, temperature or salinity. This specialisation often resulting in significant cryptic diversity.

Flight Dispersal in Supratidal Rockpool Beetles.

Flight dispersal is ecologically relevant for the survival of supratidal rockpool insects. Dispersal has important consequences for colonisation, gene flow, and evolutionary divergence. Here, we compared the flight dispersal capacity of two congeneric beetle species ( and ) that exclusively inhabit these temporary, fragmented, and extreme habitats.

Novel Microsatellite Loci, Cross-Species Validation of Multiplex Assays, and By-Catch Mitochondrial Genomes on Beetles from Supratidal Rockpools.

Here we focus on designing, for the first time, microsatellite markers for evolutionary and ecological research on aquatic beetles from the genus (Coleoptera, Hydraenidae). Some of these non-model species, with high cryptic diversity, exclusively inhabit supratidal rockpools, extreme and highly dynamic habitats with important anthropogenic threats. We analysed 15 individuals of four species (, , , and ) across 10 localities from the Mediterranean coasts of Spain and Malta.

Cuticle Hydrocarbons Show Plastic Variation under Desiccation in Saline Aquatic Beetles.

In the context of aridification in Mediterranean regions, desiccation resistance and physiological plasticity will be key traits for the persistence of aquatic insects exposed to increasing desiccation stress. Control of cuticular transpiration through changes in the quantity and composition of epicuticular hydrocarbons (CHCs) is one of the main mechanisms of desiccation resistance in insects, but it remains largely unexplored in aquatic ones. We studied acclimation responses to desiccation in adults of two endemic water beetles from distant lineages living in Mediterranean intermittent saline streams: (Hydrophilidae) and (Dytiscidae).

Role of cuticle hydrocarbons composition in the salinity tolerance of aquatic beetles.

Salinity tolerance has enabled the colonization of inland saline waters and promoted species diversification in some lineages of aquatic insects. However, the mechanisms behind this tolerance, particularly the role of cuticle hydrocarbons (CHCs), are not well-known. We characterized the CHC profile of eight species of two water beetle genera (Nebrioporus, Adephaga: Dytiscidae and Enochrus, Polyphaga: Hydrophilidae), which span the fresh-hypersaline gradient, to: i) determine the interspecific variation of CHC composition in relation to species' salinity tolerance; ii) explore plastic adjustments in CHC profiles in response to salinity changes at the intraspecific level in saline-tolerant species.

Evaluating anthropogenic impacts on naturally stressed ecosystems: Revisiting river classifications and biomonitoring metrics along salinity gradients.

Naturally stressed ecosystems hold a unique fraction of biodiversity. However, they have been largely ignored in biomonitoring and conservation programmes, such as the EU Water Framework Directive, while global change pressures are threatening their singular values. Here we present a framework to classify and evaluate the ecological quality of naturally stressed rivers along a water salinity gradient.

Effects of salinity changes on aquatic organisms in a multiple stressor context.

Under global change, the ion concentration of aquatic ecosystems is changing worldwide. Many freshwater ecosystems are being salinized by anthropogenic salt inputs, whereas many naturally saline ones are being diluted by agricultural drainages. This occurs concomitantly with changes in other stressors, which can result in additive, antagonistic or synergistic effects on organisms.

Do all roads lead to Rome? Exploring community trajectories in response to anthropogenic salinization and dilution of rivers.

Abiotic stress shapes how communities assemble and support ecological functions. However, it remains unclear whether artificially increasing or decreasing stress levels would lead to communities assembling predictably along a single axis of variation or along multiple context-dependent trajectories of change. In response to stress intensity alterations, we hypothesize that a single trajectory of change occurs when trait-based assembly prevails, while multiple trajectories of change arise when dispersal-related processes modify colonization and trait-filtering dynamics.

Insect communities in saline waters consist of realized but not fundamental niche specialists.

Considering how organisms adapt to stress is essential if we are to anticipate biological responses to global change in ecosystems. Communities in stressful environments can potentially be assembled by specialists (i.e.

The chicken or the egg? Adaptation to desiccation and salinity tolerance in a lineage of water beetles.

Transitions from fresh to saline habitats are restricted to a handful of insect lineages, as the colonization of saline waters requires specialized mechanisms to deal with osmotic stress. Previous studies have suggested that tolerance to salinity and desiccation could be mechanistically and evolutionarily linked, but the temporal sequence of these adaptations is not well established for individual lineages. We combined molecular, physiological and ecological data to explore the evolution of desiccation resistance, hyporegulation ability (i.

Cuticle hydrocarbons in saline aquatic beetles.

Hydrocarbons are the principal component of insect cuticle and play an important role in maintaining water balance. Cuticular impermeability could be an adaptative response to salinity and desiccation in aquatic insects; however, cuticular hydrocarbons have been poorly explored in this group and there are no previous data on saline species. We characterized cuticular hydrocarbons of adults and larvae of two saline aquatic beetles, namely (Dytiscidae) and (Hydrophilidae), using a gas chromatograph coupled to a mass spectrometer.

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation.

Exposing organisms to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against the two stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress.

Aquatic insects dealing with dehydration: do desiccation resistance traits differ in species with contrasting habitat preferences?

Background: Desiccation resistance shapes the distribution of terrestrial insects at multiple spatial scales. However, responses to drying stress have been poorly studied in aquatic groups, despite their potential role in constraining their distribution and diversification, particularly in arid and semi-arid regions.

Methods: We examined desiccation resistance in adults of four congeneric water beetle species (Enochrus, family Hydrophilidae) with contrasting habitat specificity (lentic vs.

Similarity in the difference: changes in community functional features along natural and anthropogenic stress gradients.

The effect of stressors on biodiversity can vary in relation to the degree to which biological communities have adapted over evolutionary time. We compared the responses of functional features of stream insect communities along chronic stress gradients with contrasting time persistence. Water salinity and land use intensification were used as examples of natural (long-term persistent) and anthropogenic (short-term persistent) stressors, respectively.

The comparative osmoregulatory ability of two water beetle genera whose species span the fresh-hypersaline gradient in inland waters (Coleoptera: Dytiscidae, Hydrophilidae).

A better knowledge of the physiological basis of salinity tolerance is essential to understanding the ecology and evolutionary history of organisms that have colonized inland saline waters. Coleoptera are amongst the most diverse macroinvertebrates in inland waters, including saline habitats; however, the osmoregulatory strategies they employ to deal with osmotic stress remain unexplored. Survival and haemolymph osmotic concentration at different salinities were examined in adults of eight aquatic beetle species which inhabit different parts of the fresh-hypersaline gradient.

Tempo and mode of the multiple origins of salinity tolerance in a water beetle lineage.

Salinity is one of the most important drivers of the distribution, abundance and diversity of organisms. Previous studies on the evolution of saline tolerance have been mainly centred on marine and terrestrial organisms, while lineages inhabiting inland waters remain largely unexplored. This is despite the fact that these systems include a much broader range of salinities, going from freshwater to more than six times the salinity of the sea (i.

How far could the alien boatman Trichocorixa verticalis verticalis spread? Worldwide estimation of its current and future potential distribution.

Invasions of alien species are considered among the least reversible human impacts, with diversified effects on aquatic ecosystems. Since prevention is the most cost-effective way to avoid biodiversity loss and ecosystem problems, one challenge in ecological research is to understand the limits of the fundamental niche of the species in order to estimate how far invasive species could spread. Trichocorixa verticalis verticalis (Tvv) is a corixid (Hemiptera) originally distributed in North America, but cited as an alien species in three continents.

Hydrological classification of natural flow regimes to support environmental flow assessments in intensively regulated Mediterranean rivers, Segura River Basin (Spain).

Hydrological classification constitutes the first step of a new holistic framework for developing regional environmental flow criteria: the "Ecological Limits of Hydrologic Alteration (ELOHA)". The aim of this study was to develop a classification for 390 stream sections of the Segura River Basin based on 73 hydrological indices that characterize their natural flow regimes. The hydrological indices were calculated with 25 years of natural monthly flows (1980/81-2005/06) derived from a rainfall-runoff model developed by the Spanish Ministry of Environment and Public Works.

Response of biotic communities to salinity changes in a Mediterranean hypersaline stream.

Background: This study investigates the relationship between salinity and biotic communities (primary producers and macroinvertebrates) in Rambla Salada, a Mediterranean hypersaline stream in SE Spain. Since the 1980's, the mean salinity of the stream has fallen from about 100 g L(-1) to 35.5 g L(-1), due to intensive irrigated agriculture in the watershed.

An ecological integrity index for littoral wetlands in agricultural catchments of semiarid mediterranean regions.

The main goal of the present study was to develop an ecological integrity index for littoral wetland management and conservation in semiarid Mediterranean areas that have been highly impacted by agriculture, including the selection of pressure and state indicators at landscape and wetlands scales that reflect the status, condition, and trends of wetlands ecosystems. We used a causality framework based on the relationship between pressure of anthropogenic activities and the ecological state of wetlands and their catchments, integrating environmental, biologic, economic, and social issues. From the application of 51 indicators in 7 littoral wetlands in the southeastern Iberian Peninsula, we selected 12 indicators (5 at catchment scale and 7 at wetland scale) to constitute the ecological integrity index proposed.