Brugger J.,Potsdam Institute for Climate Impact Research |
Brugger J.,University of Potsdam |
Brugger J.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
Feulner G.,Potsdam Institute for Climate Impact Research |
And 2 more authors.
Geophysical Research Letters | Year: 2017
Sixty-six million years ago, the end-Cretaceous mass extinction ended the reign of the dinosaurs. Flood basalt eruptions and an asteroid impact are widely discussed causes, yet their contributions remain debated. Modeling the environmental changes after the Chicxulub impact can shed light on this question. Existing studies, however, focused on the effect of dust or used one-dimensional, noncoupled atmosphere models. Here we explore the longer-lasting cooling due to sulfate aerosols using a coupled climate model. Depending on aerosol stratospheric residence time, global annual mean surface air temperature decreased by at least 26°C, with 3 to 16 years subfreezing temperatures and a recovery time larger than 30 years. The surface cooling triggered vigorous ocean mixing which could have resulted in a plankton bloom due to upwelling of nutrients. These dramatic environmental changes suggest a pivotal role of the impact in the end-Cretaceous extinction. ©2016. American Geophysical Union. 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.
Aguilar-Trigueros C.A.,Free University of Berlin |
Aguilar-Trigueros C.A.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
Powell J.R.,University of Western Sydney |
Anderson I.C.,University of Western Sydney |
And 3 more authors.
Trends in Plant Science | Year: 2014
Classification schemes have been popular to tame the diversity of root-infecting fungi. However, the usefulness of these schemes is limited to descriptive purposes. We propose that a shift to a multidimensional trait-based approach to disentangle the saprotrophic-symbiotic continuum will provide a better framework to understand fungal evolutionary ecology. Trait information reflecting the separation of root-infecting fungi from free-living soil relatives will help to understand the evolutionary process of symbiosis, the role that species interactions play in maintaining their large diversity in soil and in planta, and their contributions at the ecosystem level. Methodological advances in several areas such as microscopy, plant immunology, and metatranscriptomics represent emerging opportunities to populate trait databases. © 2014 Elsevier Ltd.
Pfestorf H.,University of Potsdam |
Korner K.,University of Potsdam |
Sonnemann I.,Free University of Berlin |
Wurst S.,Free University of Berlin |
And 3 more authors.
Journal of Vegetation Science | Year: 2016
Question: The empirical evidence of root herbivory effects on plant community composition and co-existence is contradictory. This originates from difficulties connected to below-ground research and confinement of experimental studies to a small range of environmental conditions. Here we suggest coupling experimental data with an individual-based model to overcome the limitations inherent in either approach. To demonstrate this, we investigated the consequences of root herbivory, as experimentally observed on individual plants, on plant competition and co-existence in a population and community context under different root herbivory intensities (RHI), fluctuating and constant root herbivore activity and grazing along a resource gradient. Location: Berlin, Germany, glasshouse; Potsdam, Germany, high performance cluster computer. Methods: The well-established community model IBC-Grass was adapted to allow for a flexible species parameterization and to include annual species. Experimentally observed root herbivory effects on performance of eight common grassland plant species were incorporated into the model by altering plant growth rates. We then determined root herbivore effects on plant populations, competitive hierarchy and consequences for co-existence and community diversity. Results: Root herbivory reduced individual biomass, but temporal fluctuation allowed for compensation of herbivore effects. Reducing resource availability strongly shifted competitive hierarchies, with, however, more similar hierarchies along the gradient under root herbivory, pointing to reduced ecological species differences. Consequently, negative effects on co-existence and diversity prevailed, with the exception of a few positive effects on co-existence of selected species pairs. Temporal fluctuation alleviated but did not remove negative root herbivore effects, despite of the stronger influence of intra- compared to interspecific competition. Grazing in general augmented co-existence. Most interestingly, grazing interacted with RHI and resource availability by promoting positive effects of root herbivory. Conclusions: Through integrating experimental data on the scale of individual plants with a simulation model we verified that root herbivory could affect plant competition with consequences for species co-existence. Our approach demonstrates the benefit that accrues when empirical and modelling approaches are brought more closely together, and that gathering data on distinct processes and under specific conditions, combined with appropriate models, can be used to answer challenging research questions in a more general way. © 2016 International Association for Vegetation Science.
Muller M.E.H.,Leibniz Center for Agricultural Landscape Research |
Muller M.E.H.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
Urban K.,Osnabruck University of Applied Sciences |
Koppen R.,BAM Federal Institute of Materials Research and Testing |
And 3 more authors.
World Mycotoxin Journal | Year: 2015
The role of mycotoxins in the microbial competition in an ecosystem or on the same host plant is still unclear. Therefore, a laboratory study was conducted to evaluate the influence of mycotoxins on growth and mycotoxin production of Fusarium and Alternaria fungi. Fusarium culmorum Fc13, Fusarium graminearum Fg23 and two Alternaria tenuissima isolates (At18 and At220) were incubated on wheat kernels supplemented with alternariol (AOH), tetramic acid derivates (TeA), deoxynivalenol (DON) and zearalenone (ZEA) in an in vitro test system. Fungal biomass was quantified by determining ergosterol content. Three Fusarium toxins (DON, nivalenol and ZEA) and three Alternaria toxins (AOH, alternariol methyl ether (AME) and altenuene) were analysed by HPLC-MS/MS. If Alternaria strains grew in wheat kernels spiked with Fusarium mycotoxins, their growth rates were moderately increased, their AOH and AME production was enhanced and they were simultaneously capable of degrading the Fusarium mycotoxins DON and ZEA. In contrast, both Fusarium strains behaved quite differently. The growth rate of Fc13 was not distinctly influenced, while Fg23 increased its growth in wheat kernels spiked with AOH. TeA depressed the ergosterol content in Fc13 as well as in Fg23. The DON production of Fc13 was slightly depressed, whereas the ZEA production was significantly increased. In contrast, Fg23 restricted its ZEA production. Both Fusarium strains were not capable of degrading the Alternaria mycotoxin AOH. Mycotoxins might play an important role in the interfungal competitive processes. They influence growth rates and mycotoxin production of the antagonistic combatants. The observed effects between phytopathogenic Alternaria and Fusarium strains and their mycotoxins aid the understanding of the complexity of microbial competitive behaviour in natural environments. © 2014 Wageningen Academic Publishers.
Hipsley C.A.,Leibniz Institute For Evolutions Und Biodiversitatsforschung |
Miles D.B.,Ohio University |
Muller J.,Leibniz Institute For Evolutions Und Biodiversitatsforschung |
Muller J.,Berlin Brandenburg Institute of Advanced Biodiversity Research
Biology Letters | Year: 2014
While global variation in taxonomic diversity is strongly linked to latitude, the extent to which morphological disparity follows geographical gradients is less well known. We estimated patterns of lineage diversification, morphological disparity and rates of phenotypic evolution in the Old World lizard family Lacertidae, which displays a nearly inverse latitudinal diversity gradient with decreasing species richness towards the tropics. We found that lacertids exhibit relatively constant rates of lineage accumulation over time, although the majority of morphological variation appears to have originated during recent divergence events, resulting in increased partitioning of disparity within subclades. Among subclades, tropical arboreal taxa exhibited the fastest rates of shape change while temperate European taxa were the slowest, resulting in an inverse relationship between latitudinal diversity and rates of phenotypic evolution. This pattern demonstrates a compelling counterexample to the ecological opportunity theory of diversification, suggesting an uncoupling of the processes generating species diversity and morphological differentiation across spatial scales. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Johnston P.R.,Free University of Berlin |
Johnston P.R.,Berlin Center for Genomics in Biodiversity Research |
Dobson A.J.,University College London |
Rolff J.,Free University of Berlin |
Rolff J.,Berlin Brandenburg Institute of Advanced Biodiversity Research
G3: Genes, Genomes, Genetics | Year: 2016
The evolution of resistance against antimicrobial peptides has long been considered unlikely due to their mechanism of action, yet experimental selection with antimicrobial peptides (AMPs) results in rapid evolution of resistance in several species of bacteria. Although numerous studies have utilized mutant screens to identify loci that determine AMP susceptibility, there is a dearth of data concerning the genomic changes that accompany experimental evolution of AMP resistance. Using genome resequencing, we analyzed the mutations that arose during experimental evolution of resistance to the cationic AMPs iseganan, melittin, and pexiganan, as well as to a combination of melittin and pexiganan, or to the aminoglycoside antibiotic streptomycin. Analysis of 17 independently replicated Staphylococcus aureus selection lines, including unselected controls, showed that each AMP selected for mutations at distinct loci. We identify mutations in genes involved in the synthesis and maintenance of the cell envelope. These include genes previously identified from mutant screens for AMP resistance, and genes involved in the response to AMPs and cell-wall-active antibiotics. Furthermore, transposon insertion mutants were used to verify that a number of the identified genes are directly involved in determining AMP susceptibility. Strains selected for AMP resistance under controlled experimental evolution displayed consistent AMP-specific mutations in genes that determine AMP susceptibility. This suggests that different routes to evolve resistance are favored within a controlled genetic background. © 2016 Johnston et al.
Mikolajewski D.J.,Free University of Berlin |
Rusen L.,Free University of Berlin |
Mauersberger R.,Forderverein Feldberg Uckermarkische Seenlandschaft e.V. |
Johansson F.,Uppsala University |
And 2 more authors.
Journal of Evolutionary Biology | Year: 2015
Although changes in magnitude of single traits responding to selective agents have been studied intensively, little is known about selection shaping networks of traits and their patterns of covariation. However, this is central for our understanding of phenotypic evolution as traits are embedded in a multivariate environment with selection affecting a multitude of traits simultaneously rather than individually. Here, we investigate inter- and intraspecific patterns of trait integration (trait correlations) in the larval abdomen of dragonflies as a response to a change in predator selection. Species of the dragonfly genus Leucorrhinia underwent a larval habitat shift from predatory fish to predatory dragonfly-dominated lakes with an associated relaxation in selection pressure from fish predation. Our results indicate that the habitat-shift-induced relaxed selection pressure caused phenotypic integration of abdominal traits to be reduced. Intraspecific findings matched patterns comparing species from both habitats with higher abdominal integration in response to predatory fish. This higher integration is probably a result of faster burst swimming speed. The abdomen holds the necessary morphological machinery to successfully evade predatory fish via burst swimming. Hence, abdominal traits have to function in a tight coordinated manner, as maladaptive variation and consequently nonoptimal burst swimming would cause increased mortality. In predatory dragonfly-dominated lakes, no such strong link between burst swimming and mortality is present. Our findings highlight the importance of studying multivariate trait relationships as a response to selection for understanding patterns of phenotypic diversification. © 2015 European Society For Evolutionary Biology.
Valyi K.,Free University of Berlin |
Valyi K.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
Rillig M.C.,Free University of Berlin |
Rillig M.C.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
And 2 more authors.
New Phytologist | Year: 2015
We studied the effect of host plant identity and land-use intensity (LUI) on arbuscular mycorrhizal fungi (AMF, Glomeromycota) communities in roots of grassland plants. These are relevant factors for intraradical AMF communities in temperate grasslands, which are habitats where AMF are present in high abundance and diversity. In order to focus on fungi that directly interact with the plant at the time, we investigated root-colonizing communities. Our study sites represent an LUI gradient with different combinations of grazing, mowing, and fertilization. We used massively parallel multitag pyrosequencing to investigate AMF communities in a large number of root samples, while being able to track the identity of the host. We showed that host plants significantly differed in AMF community composition, while land use modified this effect in a plant species-specific manner. Communities in medium and low land-use sites were subsets of high land-use communities, suggesting a differential effect of land use on the dispersal of AMF species with different abundances and competitive abilities. We demonstrate that in these grasslands, there is a small group of highly abundant, generalist fungi which represent the dominating species in the AMF community. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.
Andrade-Linares D.R.,Free University of Berlin |
Andrade-Linares D.R.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
Veresoglou S.D.,Free University of Berlin |
Veresoglou S.D.,Berlin Brandenburg Institute of Advanced Biodiversity Research |
And 2 more authors.
Fungal Ecology | Year: 2016
Most soil fungi experience a constantly fluctuating environment, and coping with resulting biotic and abiotic stressors can come at a considerable metabolic cost. We know that organisms respond better to severe stresses (triggering stress) when they have experienced a similar milder stress (priming stress) before. Asking how long organisms can remember a priming event is a compelling question. We here studied priming by temperature stress in filamentous fungi isolated from the same grassland soil. We hypothesized that filamentous fungi can show priming responses, and that their memory-spans correlate with their growth rates. Fungal colonies of 19 different filamentous fungi were first primed at 35 °C for 5 h (as priming stress) and after 0, 6, 12, 24 or 48 h they were exposed to 40 °C for 10 h (as triggering stress). The variable lag time between the stress applications allowed us to assess memory. Our main response variable was growth rate. Of the 19 fungal isolates tested, eight showed temperature priming ability. The Mucoromycotina isolates (Mortierellales) showed a mean growth increase following triggering stress that was 2.75-fold higher than in unprimed colonies (log-response-ratio). Mucoromycotina isolates had a memory half-life span (power-law-relationships) of 5.65 h. Considering fungal traits like growth rate to predict priming responses, we found a positive relationship between priming response (with 12 h memory phase) and growth rate. The differential ability to be primed in co-occurring isolates may have direct consequences for fungal communities and coexistence in soil. © 2016 Elsevier Ltd and The British Mycological Society.