Current Water Management of Small Lotic Waterbodies in the Context of Nature Conservation in Germany.

Small lotic waterbodies are abundant and species rich habitats, offering refuges and microhabitats to protected species of the European Union Habitats Directive. Highly impacted by water management actions, it is essential to reveal the current status and challenges of water management. The present study aims to identify relevant issues by conducting a survey concerning water management authorities. Authorities were selected according to their involvement in the management of small lotic waterbodies within the actual range of a threatened species, Coenagrion mercuriale (Odonata), which is highly dependent on water management actions and protected by the Habitats Directive. The survey involved three sets of questionnaires, (1) socio-demographic (personal) questions (2) specific questions about water management and (3) questions on the biological background. Out of 181 selected authorities, 75 participated in the survey. The results showed that though nature conservation interests are partially considered, they represented a minor factor in water management decision-making. In addition, knowledge exchange is insufficient between involved stakeholders from policy, management practice and science, which was especially reflected in the case of equipment use and accruing material. The reconciliation of both, water management and nature conservation interests, can contribute to enhance the conservation status of key protected species of small lotic waterbodies under the Habitats Directive.

Metabarcoding dietary analysis in the insectivorous bat Nyctalusleisleri and implications for conservation.

In this study, we aim to uncover diet preferences for the insectivorous bat Nyctalusleisleri (Leisler's bat, the lesser noctule) and to provide recommendations for conservation of the species, based on the analysis of prey source habitats. Using a novel guano trap, we sampled bat faeces at selected roosts in a forest in Germany and tested two mitochondrial markers (COI and 16S) and three primer pairs for the metabarcoding of bat faecal pellets. We found a total of 17 arthropod prey orders comprising 358 species in N.leisleri guano. The most diverse orders were Lepidoptera (126 species), Diptera (86 species) and Coleoptera (48 species), followed by Hemiptera (28 species), Trichoptera (16 species), Neuroptera (15 species) and Ephemeroptera (10 species), with Lepidoptera species dominating in spring and Diptera in summer. Based on the ecological requirements of the most abundant arthropod species found in the bat guano, we propose some recommendations for the conservation of N.leisleri that are relevant for other insectivorous bat species.

Updating the list of flower-visiting bees, hoverflies and wasps in the central atolls of Maldives, with notes on land-use effects.

Maldives islands host a unique biodiversity, but their integrity is threatened by climate change and impacting land-uses (e.g. cemented or agricultural areas). As pollinators provide key services for the ecosystems and for the inhabitants, it is crucial to know which pollinators occur in the islands, to characterise their genetic identity and to understand which plants they visit and the size of the human impact. Given that no significant faunistic surveys of Hymenoptera have been published for the country in more than 100 years and that Syrphidae were only partly investigated, we sampled islands in the central part of the Maldives country (Faafu and Daahlu atolls) and hand-netted flower-visiting bees, wasps and hoverflies (Hymenoptera: Anthophila, Crabronidae, Sphecidae, Vespidae, Scoliidae and Diptera: Syrphidae). Overall, we found 21 species; 76.4% of the collected specimens were Anthophila (bees), 12.7% belonged to several families of wasps and 10.8% of individuals were Syrphidae. It seems that one third of species are new for the Maldives, based on the published literature. Human land-uses seem to shape the local pollinator fauna since the assemblages of bees, wasps and hoverflies from urbanised and agricultural islands differed from those in resort and natural ones. These pollinators visited 30 plant species in total, although some invasive plants hosted the highest number of flower visitor species. Biogeographically, this pollinating fauna is mostly shared with Sri Lanka and India. Genetically, the used marker hinted for a unique fauna in relation to the rest of the distribution ranges in most cases, although generally within the level of intraspecific genetic variation. This study significantly contributes to increasing the knowledge on the pollinator diversity and genetic identity in Maldives islands also considering the important implications for the islands' land-use and the role of invasive plants. This study will be pivotal for future pollination studies and biodiversity conservation efforts in the region.

Insect biomass decline scaled to species diversity: General patterns derived from a hoverfly community.

Reports of declines in biomass of flying insects have alarmed the world in recent years. However, how biomass declines reflect biodiversity loss is still an open question. Here, we analyze the abundance (19,604 individuals) of 162 hoverfly species (Diptera: Syrphidae), at six locations in German nature reserves in 1989 and 2014, and generalize the results with a model varying decline rates of common vs. rare species. We show isometric decline rates between total insect biomass and total hoverfly abundance and a scale-dependent decline in hoverfly species richness, ranging between -23% over the season to -82% at the daily level. We constructed a theoretical null model to explore how strong declines in total abundance translate to changing rank-abundance curves, species persistence, and diversity measures. Observed persistence rates were disproportionately lower than expected for species of intermediate abundance, while the rarest species showed decline and appearance rates consistent with random expectation. Our results suggest that large insect biomass declines are predictive of insect diversity declines. Under current threats, even the more common species are in peril, calling for a reevaluation of hazards and conservation strategies that traditionally target already rare and endangered species only.

Specialization of plant-pollinator interactions increases with temperature at Mt. Kilimanjaro.

AIM: Species differ in their degree of specialization when interacting with other species, with significant consequences for the function and robustness of ecosystems. In order to better estimate such consequences, we need to improve our understanding of the spatial patterns and drivers of specialization in interaction networks. METHODS: Here, we used the extensive environmental gradient of Mt. Kilimanjaro (Tanzania, East Africa) to study patterns and drivers of specialization, and robustness of plant-pollinator interactions against simulated species extinction with standardized sampling methods. We studied specialization, network robustness and other network indices of 67 quantitative plant-pollinator networks consisting of 268 observational hours and 4,380 plant-pollinator interactions along a 3.4 km elevational gradient. Using path analysis, we tested whether resource availability, pollinator richness, visitation rates, temperature, and/or area explain average specialization in pollinator communities. We further linked pollinator specialization to different pollinator taxa, and species traits, that is, proboscis length, body size, and species elevational ranges. RESULTS: We found that specialization decreased with increasing elevation at different levels of biological organization. Among all variables, mean annual temperature was the best predictor of average specialization in pollinator communities. Specialization differed between pollinator taxa, but was not related to pollinator traits. Network robustness against simulated species extinctions of both plants and pollinators was lowest in the most specialized interaction networks, that is, in the lowlands. CONCLUSIONS: Our study uncovers patterns in plant-pollinator specialization along elevational gradients. Mean annual temperature was closely linked to pollinator specialization. Energetic constraints, caused by short activity timeframes in cold highlands, may force ectothermic species to broaden their dietary spectrum. Alternatively or in addition, accelerated evolutionary rates might facilitate the establishment of specialization under warm climates. Despite the mechanisms behind the patterns have yet to be fully resolved, our data suggest that temperature shifts in the course of climate change may destabilize pollination networks by affecting network architecture.

Climate-land-use interactions shape tropical mountain biodiversity and ecosystem functions.

Agriculture and the exploitation of natural resources have transformed tropical mountain ecosystems across the world, and the consequences of these transformations for biodiversity and ecosystem functioning are largely unknown1-3. Conclusions that are derived from studies in non-mountainous areas are not suitable for predicting the effects of land-use changes on tropical mountains because the climatic environment rapidly changes with elevation, which may mitigate or amplify the effects of land use4,5. It is of key importance to understand how the interplay of climate and land use constrains biodiversity and ecosystem functions to determine the consequences of global change for mountain ecosystems. Here we show that the interacting effects of climate and land use reshape elevational trends in biodiversity and ecosystem functions on Africa's largest mountain, Mount Kilimanjaro (Tanzania). We find that increasing land-use intensity causes larger losses of plant and animal species richness in the arid lowlands than in humid submontane and montane zones. Increases in land-use intensity are associated with significant changes in the composition of plant, animal and microorganism communities; stronger modifications of plant and animal communities occur in arid and humid ecosystems, respectively. Temperature, precipitation and land use jointly modulate soil properties, nutrient turnover, greenhouse gas emissions, plant biomass and productivity, as well as animal interactions. Our data suggest that the response of ecosystem functions to land-use intensity depends strongly on climate; more-severe changes in ecosystem functioning occur in the arid lowlands and the cold montane zone. Interactions between climate and land use explained-on average-54% of the variation in species richness, species composition and ecosystem functions, whereas only 30% of variation was related to single drivers. Our study reveals that climate can modulate the effects of land use on biodiversity and ecosystem functioning, and points to a lowered resistance of ecosystems in climatically challenging environments to ongoing land-use changes in tropical mountainous regions.

Close relatives of Mediterranean endemo-relict hoverflies (Diptera, Syrphidae) in South Africa: Morphological and molecular evidence in the Merodon melanocerus subgroup.

An ongoing study of the genus Merodon Meigen, 1803 in the Republic of South Africa (RSA) has revealed the existence of new species related to M. melanocerus Bezzi, 1915. The M. melanocerus subgroup belongs to the Afrotropical lineage of the M. desuturinus group. Revision of all available material from museums and detailed analyses of newly -collected specimens from our own expeditions to RSA resulted in delimitation of five species: M. capensis Hurkmans sp. n., M. commutabilis Radenkovic et Vujic sp. n., M. drakonis Vujic et Radenkovic sp. n., M. flavocerus Hurkmans sp. n. and M. melanocerus. In addition to classical morphological characters, sequences of the mitochondrial COI gene are provided for four related taxa. Results of molecular phylogenetic analyses supports monophyly of the M. desuturinus group and confirmed delimitation between species. Links between Palaearctic and Afrotropical faunas of this group, as well as possible evolutionary paths, are discussed. Based on phylogenetic analyses, four lineages (putative subgenera) have been recognized within the genus Merodon; besides the three previously established ones, albifrons+desuturinus, aureus (sensu lato) and avidus-nigritarsis, one new lineage named natans is distinguished.

Predictors of elevational biodiversity gradients change from single taxa to the multi-taxa community level.

The factors determining gradients of biodiversity are a fundamental yet unresolved topic in ecology. While diversity gradients have been analysed for numerous single taxa, progress towards general explanatory models has been hampered by limitations in the phylogenetic coverage of past studies. By parallel sampling of 25 major plant and animal taxa along a 3.7 km elevational gradient on Mt. Kilimanjaro, we quantify cross-taxon consensus in diversity gradients and evaluate predictors of diversity from single taxa to a multi-taxa community level. While single taxa show complex distribution patterns and respond to different environmental factors, scaling up diversity to the community level leads to an unambiguous support for temperature as the main predictor of species richness in both plants and animals. Our findings illuminate the influence of taxonomic coverage for models of diversity gradients and point to the importance of temperature for diversification and species coexistence in plant and animal communities.