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Wich S.A.,University of Amsterdam | Garcia-Ulloa J.,ETH Zurich | Kuhl H.S.,German Center for Integrative Biodiversity Research | Kuhl H.S.,Max Planck Institute for Evolutionary Anthropology | And 3 more authors.
Current Biology | Year: 2014

Expansion of oil palm plantations has led to extensive wildlife habitat conversion in Southeast Asia [1]. This expansion is driven by a global demand for palm oil for products ranging from foods to detergents [2], and more recently for biofuels [3]. The negative impacts of oil palm development on biodiversity [1, 4, 5], and on orangutans (Pongo spp.) in particular, have been well documented [6, 7] and publicized [8, 9]. Although the oil palm is of African origin, Africa's production historically lags behind that of Southeast Asia. Recently, significant investments have been made that will likely drive the expansion of Africa's oil palm industry [10]. There is concern that this will lead to biodiversity losses similar to those in Southeast Asia. Here, we analyze the potential impact of oil palm development on Africa's great apes. Current great ape distribution in Africa substantially overlaps with current oil palm concessions (by 58.7%) and areas suitable for oil palm production (by 42.3%). More importantly, 39.9% of the distribution of great ape species on unprotected lands overlaps with suitable oil palm areas. There is an urgent need to develop guidelines for the expansion of oil palm in Africa to minimize the negative effects on apes and other wildlife. There is also a need for research to support land use decisions to reconcile economic development, great ape conservation, and avoiding carbon emissions. © 2014 Elsevier Ltd All rights reserved.

Grossiord C.,French National Institute for Agricultural Research | Granier A.,French National Institute for Agricultural Research | Ratcliffe S.,University of Leipzig | Bouriaud O.,Stefan Cel Mare University of Suceava | And 13 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Climate models predict an increase in the intensity and frequency of drought episodes in the Northern Hemisphere. Among terrestrial ecosystems, forests will be profoundly impacted by drier climatic conditions, with drastic consequences for the functions and services they supply. Simultaneously, biodiversity is known to support a wide range of forest ecosystem functions and services. However, whether biodiversity also improves the resistance of these ecosystems to drought remains unclear. We compared soil drought exposure levels in a total of 160 forest stands within five major forest types across Europe along a gradient of tree species diversity. We assessed soil drought exposure in each forest stand by calculating the stand-level increase in carbon isotope composition of latewood from a wet to a dry year (Δδ13CS). Δδ13CS exhibited a negative linear relationship with tree species diversity in two forest types, suggesting that species interactions in these forests diminished the drought exposure of the ecosystem. However, the other three forest typeswere unaffected by tree species diversity. We conclude that higher diversity enhances resistance to drought events only in drought-prone environments. Managing forest ecosystems for high tree species diversity does not necessarily assure improved adaptability to themore severe and frequent drought events predicted for the future.

Hanspach J.,Helmholtz Center for Environmental Research | Hanspach J.,Lüneburg University | Schweiger O.,Helmholtz Center for Environmental Research | Kuhn I.,Helmholtz Center for Environmental Research | And 6 more authors.
Ecography | Year: 2014

Species ranges are shaped by both climatic factors and interactions with other species. The stress gradient hypothesis predicts that under physiologically stressful environmental conditions abiotic factors shape range edges while in less stressful environments negative biotic interactions are more important. Butterflies provide a suitable system to test this hypothesis since larvae of most species depend on biotic interactions with a specific set of host plants, which in turn can shape patterns of occurrence and distribution. Here we modelled the distribution of 92 butterfly and 136 host plant species with three different modelling algorithms, using distribution data from the Swiss biodiversity monitoring scheme at a 1 × 1 km spatial resolution. By comparing the ensemble prediction for each butterfly species and the corresponding host plant(s), we assessed potential constraints imposed by host plant availability on distribution of butterflies at their distributional limits along the main environmental gradient, which closely parallels an elevational gradient. Our results indicate that host limitation does not play a role at the lower limit. At the upper limit 50% of butterfly species have a higher elevational limit than their primary host plant, and 33% have upper elevational limits that exceed the limits of both primary and secondary hosts. We conclude that host plant limitation was not relevant to butterfly distributional limits in less stressful environments and that distributions are more likely limited by climate, land use or antagonistic biotic interactions. Obligatory dependency of butterflies on their host plants, however, seems to represent an important limiting factor for the distribution of some species towards the cold, upper end of the environmental gradient, suggesting that biotic factors can shape ranges in stressful environments. Thus, predictions by the stress gradient hypothesis were not always applicable. © 2013 The Authors.

Hantsch L.,Martin Luther University of Halle Wittenberg | Braun U.,Martin Luther University of Halle Wittenberg | Scherer-Lorenzen M.,Albert Ludwigs University of Freiburg | Bruelheide H.,Martin Luther University of Halle Wittenberg | Bruelheide H.,German Center for Integrative Biodiversity Research
Ecosphere | Year: 2013

Current theory on transmission rates of plant pathogens predicts a strong influence of host richness on the degree of infection. In addition, identity effects, caused by the presence of particular species in a community, may also drive biodiversity and ecosystem functioning relationships, with "selection" or "sampling effects" being particularly important. We tested the effect of tree species richness and tree species identity effects on foliar fungal pathogens on four forest tree species of the temperate zone making use of the BIOTREE tree diversity experiment in Germany. We hypothesized that fungal species richness is positively and fungal pathogen load negatively related to tree species richness. In addition, we tested whether species number of foliar biotrophic fungi and pathogen load depend on tree community composition and on the presence or absence of particular disease-prone tree species. All foliar fungi were identified macro- and microscopically and subjected to statistical analyses at three hierarchical levels, at the plot level, the level of single tree species and the level of individual fungus species. There was a negative effect of tree richness on the pathogen load of common powdery mildew species. Moreover, we found strong tree species identity effects at the plot level as the presence of Quercus resulted in a high pathogen load. Thus, for the first time we experimentally showed that disease risk and pathogen transmission of foliar fungal pathogens in temperate forest tree ecosystems may depend on tree richness and on the presence of particular disease-prone species. © 2013 Hantsch et al.

News Article | March 2, 2017
Site: www.eurekalert.org

A core set of genes involved in the responses of honey bees to multiple diseases caused by viruses and parasites has been identified by an international team of researchers. The findings provide a better-defined starting point for future studies of honey-bee health, and may help scientists and beekeepers breed honey bees that are more resilient to stress. "In the past decade, honey-bee populations have experienced severe and persistent losses across the Northern Hemisphere, mainly due to the effects of pathogens, such as fungi and viruses," said Vincent Doublet, postdoctoral research fellow, University of Exeter. "The genes that we identified offer new possibilities for the generation of honey-bee stocks that are resistant to these pathogens." According to the researchers, recent advances in DNA sequencing have prompted numerous investigations of the genes involved in honey-bee responses to pathogens. Yet, until now, this vast quantity of data has been too cumbersome and idiosyncratic to reveal overarching patterns in honey-bee immunity. "While many studies have used genomic approaches to understand how bees respond to viruses and parasites, it has been difficult to compare across these studies to find the core genes and pathways that help the bee fight off stressors," said Distinguished Professor of Entomology Christina Grozinger, Penn State. "Our team created a new bioinformatics tool that has enabled us to integrate information from 19 different genomic datasets to identify the key genes involved in honey bees' response to diseases." Specifically, the team of 28 researchers, representing eight countries, created a new statistical technique, called directed rank-product analysis. The technique allowed them to identify the genes that were expressed similarly across the 19 datasets, rather than just the genes that were expressed more than others within a dataset. The scientists found that these similarly expressed genes included those that encode proteins responsible for the response to tissue damage by pathogens, and those that encode enzymes involved in the metabolism of carbohydrates from food, among many others. A decrease in carbohydrate metabolism, they suggested, may illustrate the cost of the infection on the organism. The researchers report their findings in today's (Mar. 2) issue of BMC Genomics. "Honey bees were thought to respond to different disease organisms in entirely different ways, but we have learned that they mostly rely on a core set of genes that they turn on or off in response to any major pathogenic challenge," said Robert Paxton, professor of zoology, German Centre for Integrative Biodiversity Research. "We can now explore the physiological mechanisms by which pathogens overcome their honey-bee hosts, and how honey bees can fight back against those pathogens." The implications of the findings are not limited to honey bees. The team found that the core genes are part of conserved pathways -- meaning they have been maintained throughout the course of evolution among insects and therefore are shared by other insects. According to Doublet, this means that the genes provide important knowledge for understanding pathogen interactions with other insects, such as bumble bees, and for using pathogens to control insect pests, such as aphids and certain moths. "This analysis provides unprecedented insight into the mechanisms that underpin the interactions between insects and their pathogens," said Doublet. "With this analysis, we generated a list of genes that will likely be an important source for future functional studies, for breeding more resilient honey-bee stocks and for controlling emerging bee diseases." This research was supported by iDiv, the German Center for Integrative Biodiversity Research, located in Leipzig, Germany. Other authors on the paper include Yvonne Poeschl, German Centre for Integrative Biodiversity Research; Andreas Gogol-Döring, Technische Hochschule Mittelhessen; Cédric Alaux, INRA; Desiderato Annoscia, Università degli Studi di Udine; Christian Aurori, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca; Seth Barribeau, University of Liverpool; Oscar Bedoya-Reina, University of Edinburgh; Mark Brown, Royal Holloway University of London; James Bull, Swansea University; Michelle Flenniken, Montana State University; David Galbraith, Penn State; Elke Genersch, Institute for Bee Research of Hohen Neuendorf; Sebastian Gisder, Institute for Bee Research of Hohen Neuendorf; Ivo Grosse, Martin Luther University Halle-Wittenberg; Holly Holt, University of Minnesota; Dan Hultmark, Umeå University; H. Michael G. Lattorff, International Centre of Insect Physiology and Ecology; Yves Le Conte, INRA; Fabio Manfredini, Royal Holloway University of London; Dino McMahon, Freie Universität Berlin; Robin Moritz, Martin Luther University Halle-Wittenberg; Francesco Nazzi, Università degli Studi di Udine; Elina Niño, University of California, Davis; Katja Nowick, University of Leipzig; and Ronald van Rij, Radboud University.

Grace J.B.,U.S. Geological Survey | Anderson T.M.,Wake forest University | Seabloom E.W.,University of Minnesota | Borer E.T.,University of Minnesota | And 24 more authors.
Nature | Year: 2016

How ecosystem productivity and species richness are interrelated is one of the most debated subjects in the history of ecology. Decades of intensive study have yet to discern the actual mechanisms behind observed global patterns. Here, by integrating the predictions from multiple theories into a single model and using data from 1,126 grassland plots spanning five continents, we detect the clear signals of numerous underlying mechanisms linking productivity and richness. We find that an integrative model has substantially higher explanatory power than traditional bivariate analyses. In addition, the specific results unveil several surprising findings that conflict with classical models. These include the isolation of a strong and consistent enhancement of productivity by richness, an effect in striking contrast with superficial data patterns. Also revealed is a consistent importance of competition across the full range of productivity values, in direct conflict with some (but not all) proposed models. The promotion of local richness by macroecological gradients in climatic favourability, generally seen as a competing hypothesis, is also found to be important in our analysis. The results demonstrate that an integrative modelling approach leads to a major advance in our ability to discern the underlying processes operating in ecological systems. © 2016 Macmillan Publishers Limited.

Meldau D.G.,Max Planck Institute for Chemical Ecology | Meldau S.,Max Planck Institute for Chemical Ecology | Meldau S.,German Center for Integrative Biodiversity Research | Hoang L.H.,Institute of Agricultural Genetics | And 3 more authors.
Plant Cell | Year: 2013

Bacillus sp B55, a bacterium naturally associated with Nicotiana attenuata roots, promotes growth and survival of wild-type and, particularly, ethylene (ET)-insensitive 35S-ethylene response1 (etr1) N. attenuata plants, which heterologously express the mutant Arabidopsis thaliana receptor ETR1-1. We found that the volatile organic compound (VOC) blend emitted by B55 promotes seedling growth, which is dominated by the S-containing compound dimethyl disulfide (DMDS). DMDS was depleted from the headspace during cocultivation with seedlings in bipartite Petri dishes, and 35S was assimilated from the bacterial VOC bouquet and incorporated into plant proteins. In wild-type and 35S-etr1 seedlings grown under different sulfate (SO4 -2) supply conditions, exposure to synthetic DMDS led to genotype-dependent plant growth promotion effects. For the wild type, only S-starved seedlings benefited from DMDS exposure. By contrast, growth of 35S-etr1 seedlings, which we demonstrate to have an unregulated S metabolism, increased at all SO4 -2 supply rates. Exposure to B55 VOCs and DMDS rescued many of the growth phenotypes exhibited by ET-insensitive plants, including the lack of root hairs, poor lateral root growth, and low chlorophyll content. DMDS supplementation significantly reduced the expression of S assimilation genes, as well as Met biosynthesis and recycling. We conclude that DMDS by B55 production is a plant growth promotion mechanism that likely enhances the availability of reduced S, which is particularly beneficial for wild-type plants growing in S-deficient soils and for 35S-etr1 plants due to their impaired S uptake/assimilation/metabolism. © 2013 American Society of Plant Biologists. All rights reserved.

PubMed | Institute of Virology, Berlin Institute for Medical Systems Biology and German Center for Integrative Biodiversity Research
Type: Journal Article | Journal: Journal of virology | Year: 2016

Adeno-associated virus (AAV) is recognized for its bipartite life cycle with productive replication dependent on coinfection with adenovirus (Ad) and AAV latency being established in the absence of a helper virus. The shift from latent to Ad-dependent AAV replication is mostly regulated at the transcriptional level. The current AAV transcription map displays highly expressed transcripts as found upon coinfection with Ad. So far, AAV transcripts have only been characterized on the plus strand of the AAV single-stranded DNA genome. The AAV minus strand is assumed not to be transcribed. Here, we apply Illumina-based RNA sequencing (RNA-Seq) to characterize the entire AAV2 transcriptome in the absence or presence of Ad. We find known and identify novel AAV transcripts, including additional splice variants, the most abundant of which leads to expression of a novel 18-kDa Rep/VP fusion protein. Furthermore, we identify for the first time transcription on the AAV minus strand with clustered reads upstream of the p5 promoter, confirmed by 5 rapid amplification of cDNA ends and RNase protection assays. The p5 promoter displays considerable activity in both directions, a finding indicative of divergent transcription. Upon infection with AAV alone, low-level transcription of both AAV strands is detectable and is strongly stimulated upon coinfection with Ad.Next-generation sequencing (NGS) allows unbiased genome-wide analyses of transcription profiles, used here for an in depth analysis of the AAV2 transcriptome during latency and productive infection. RNA-Seq analysis led to the discovery of novel AAV transcripts and splice variants, including a derived, novel 18-kDa Rep/VP fusion protein. Unexpectedly, transcription from the AAV minus strand was discovered, indicative of divergent transcription from the p5 promoter. This finding opens the door for novel concepts of the switch between AAV latency and productive replication. In the absence of a suitable animal model to study AAV in vivo, combined in cellulae and in silico studies will help to forward the understanding of the unique, bipartite AAV life cycle.

Larsen S.,German Center for Integrative Biodiversity Research | Scalici M.,Third University of Rome | Tancioni L.,University of Rome Tor Vergata
Aquatic Sciences | Year: 2015

Although the important contribution of β-diversity to regional (γ) diversity is increasingly recognised, our understanding of how the spatial scaling of β-diversity differs among taxonomic groups is still limited, especially in dynamic lotic ecosystems. In this study, we assessed the difference in the partitioning of diversity at nested spatial scales, from reach to catchment, among riparian birds, fish and benthic macroinvertebrates in Mediterranean river systems. Fish and macroinvertebrates showed similar scaling patterns, with β-diversity always larger than expected by a random distribution of individuals at all spatial scales (among reaches, rivers and catchments), and local (α) diversity always lower than expected. Conversely, β-diversity of riparian birds appeared larger than expected only at the largest scale (among catchments), while local diversity did not differ from random expectation. For birds, however, results partly depended on the weighting of abundant and rare species. Although the relative contribution of β to γ-diversity did not differ substantially among groups (with multiplicative β representing five to six distinct communities), its deviation from random expectations showed marked differences indicating that functionally different groups exhibit distinct spatial patterns. This study is among the first to investigate scaling patterns in β-diversity across taxonomic groups with different ecological requirements and dispersal ability, and provides a holistic picture of riverine biodiversity. From a conservation perspective, the results suggest that, in these river systems, flexible conservation strategies are required in order to protect multiple taxonomic groups. © 2014, Springer Basel.

Larsen S.,German Center for Integrative Biodiversity Research | Alp M.,University Paul Sabatier
Limnology | Year: 2015

Ecological thresholds represent the point at which an ecological process or parameter changes abruptly in response to relatively small changes in a driving force. Although the non-linear nature of ecological dynamics is widely recognised, the concept of threshold responses has only recently received the warranted attention in conservation and management. In this short review we synthesise current knowledge on ecological thresholds and alternative stable states and review examples of threshold responses in riparian wetlands. The review shows that changes in the hydrologic regime often represent the trigger that causes abrupt shifts in riparian species composition. Also, inputs of nutrients over critical loads can cause drastic changes in wetland biogeochemical functions. We then discuss the implications of threshold relationships for the management of riparian wetlands. Critical steps needed to embody threshold models in adaptive management include the assessment of wetlands' predisposition to threshold responses and the adaptation of monitoring schemes to facilitate the statistical identification of nonlinear relationships. Future research should also aim at assessing how climate change may influence the likelihood of ecological thresholds. Also, as the dynamics of degraded ecosystems often differ substantially from those of pristine systems, a better understanding of human modified systems is necessary for the development of a predictive framework. © 2014, The Japanese Society of Limnology.

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