Refine
Year of publication
Document Type
- Article (3346)
- Doctoral Thesis (734)
- Postprint (283)
- Review (125)
- Other (82)
- Conference Proceeding (54)
- Monograph/Edited Volume (19)
- Preprint (18)
- Habilitation Thesis (12)
- Part of Periodical (7)
Language
- English (4684) (remove)
Keywords
- Arabidopsis thaliana (59)
- climate change (47)
- Arabidopsis (38)
- ancient DNA (30)
- biodiversity (30)
- evolution (24)
- Dictyostelium (22)
- animal personality (22)
- functional traits (22)
- adaptation (19)
Institute
- Institut für Biochemie und Biologie (4684) (remove)
The human face shows individual features and features that are characteristic for sex and age (the loss of childlike characteristics during maturation). The analysis of facial dimensions is essential for identifying individual features also for forensic issues.
The analysis of facial proportions was performed on photogrammetric data from front views of 125 children. The data were pooled from 2 different studies. The children's data were obtained from a longitudinal study and reduced by random generator to ensure the data of adults from a separate cross-sectional study.
We applied principal component analysis on photogrammetric facial proportions of 169 individuals: 125 children (63 boys and 62 girls) aged 2-7 years and 44 adults (18 men and 26 women) aged 18-65 years.
Facial proportions depend on age and sex. Three components described age: (1) proportions of facial height to head height, (2) proportions that involve endocanthal breadth, and (3) bigonial to bizygonial proportions. Proportions that associate with sex are connected with nasal distances and nasal to bizygonial distances.
Twenty-three percent of the variance, particularly variance that are connected with proportions of lower and middle face heights to head height, do neither depend on sex nor on age and thus appear useful for screening purposes, eg, for dysmorphic genetic syndromes.
Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5–25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO2) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO2 beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs.
Plastic pollution is an increasing environmental problem, but a comprehensive understanding of its effect in the environment is still missing. The wide variety of size, shape, and polymer composition of plastics impedes an adequate risk assessment. We investigated the effect of differently sized polystyrene beads (1-, 3-, 6-µm; PS) and polyamide fragments (5–25 µm, PA) and non-plastics items such as silica beads (3-µm, SiO2) on the population growth, reproduction (egg ratio), and survival of two common aquatic micro invertebrates: the rotifer species Brachionus calyciflorus and Brachionus fernandoi. The MPs were combined with food quantity, limiting and saturating food concentration, and with food of different quality. We found variable fitness responses with a significant effect of 3-µm PS on the population growth rate in both rotifer species with respect to food quantity. An interaction between the food quality and the MPs treatments was found in the reproduction of B. calyciflorus. PA and SiO2 beads had no effect on fitness response. This study provides further evidence of the indirect effect of MPs in planktonic rotifers and the importance of testing different environmental conditions that could influence the effect of MPs.
One potential trade-off that bold individuals face is between increased predation risks and gains in resources. Individuals experiencing high predation and hungry individuals (or individuals with low body condition) are predicted to show increased boldness. We examined one behavioral trait previously reported to be associated with boldness (the time individual fish needed to emerge from shelter) in various populations of mollies (Poecilia spp.). Our study system included several southern Mexican surface streams with high piscine predation and high food availability, sulfidic surface streams with high avian predation, in which the inhabiting fish show reduced body condition, and a sulfidic cave, where predation and body condition are low. Our comparison revealed very short times to emerge from the start box in populations from non-sulfidic streams. In sulfidic habitats (whether surface or cave), it took individual Poecilia mexicana considerably longer to emerge from the start box, and the same difference was also found in an independent comparison between P. mexicana and the closely related, highly sulfide-adapted Poecilia sulphuraria. Fish reared under common garden conditions (in the absence of predators and hydrogen sulfide) showed intermediate boldness scores to the extremes observed in the field. Our data thus indicate that (a) boldness is shaped by environmental conditions/ experiential effects, but is not heritable, (b) predation affects boldness in the predicted direction, but (c) low body condition leads to reduced boldness. Extremophile Poecilia spp. spend most of their time surfacing to survive under sulfidic and hypoxic conditions, which exposes them to increased levels of predations, but the fish forage on the bottom. Hence, in this system, increased boldness does not increase foraging success. We argue that energy limitation favors reducing energetically costly behaviors, and exploring novel environments may be just one of them.
Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.
Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.
Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.
Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local -scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha(-1) yr(- 1)). N deposition was on average higher ton clay-rich luvisols than on brunisols, and areas burned 1-15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition
Variation in nitrogen deposition and available soil nitrogen in a forest–grassland ecotone in Canada
(2004)
Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha⁻¹ yr⁻¹). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 – 15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition.
Resource distribution heterogeneity offers niche opportunities for species with different functional traits to develop and potentially coexist. Available light (photosynthetically active radiation or PAR) for suspended algae (phytoplankton) may fluctuate greatly over time and space. Species-specific light acquisition traits capture important aspects of the ecophysiology of phytoplankton and characterize species growth at either limiting or saturating daily PAR supply. Efforts have been made to explain phytoplankton coexistence using species-specific light acquisition traits under constant light conditions, but not under fluctuating light regimes that should facilitate non-equilibrium coexistence. In the well-mixed, hypertrophic Lake TaiHu (China), we incubated the phytoplankton community in bottles placed either at fixed depths or moved vertically through the water column to mimic vertical mixing. Incubations at constant depths received only the diurnal changes in light, while the moving bottles received rapidly fluctuating light. Species-specific light acquisition traits of dominant cyanobacteria (Anabaena flos-aquae, Microcystis spp.) and diatom (Aulacoseira granulata, Cyclotella pseudostelligera) species were characterized from their growth-light relationships that could explain relative biomasses along the daily PAR gradient under both constant and fluctuating light. Our study demonstrates the importance of interspecific differences in affinities to limiting and saturating light for the coexistence of phytoplankton species in spatially heterogeneous light conditions. Furthermore, we observed strong intraspecific differences in light acquisition traits between incubation under constant and fluctuating light - leading to the reversal of light utilization strategies of species. This increased the niche space for acclimated species, precluding competitive exclusion. These observations could enhance our understanding of the mechanisms behind the Paradox of the Plankton.
Understanding the molecular basis of morphological change remains a central challenge in evolutionary-developmental biology. The transition from outbreeding to selfing is often associated with a dramatic reduction in reproductive structures and functions, such as the loss of attractive pheromones in hermaphroditic Caenorhabditis elegans and a reduced flower size in plants. Here, we demonstrate that variation in the level of the brassinosteroid-biosynthesis enzyme CYP724A1 contributes to the reduced flower size of selfing Capsella rubella compared with its outbreeding ancestor Capsella grandiflora. The primary transcript of the C. rubella allele is spliced more efficiently than that of C. grandiflora, resulting in higher brassinosteroid levels. These restrict organ growth by limiting cell proliferation. More efficient splicing of the C. rubella allele results from two de novo mutations in the selfing lineage. Thus, our results highlight the potentially widespread importance of differential splicing efficiency and higher-than-optimal hormone levels in generating phenotypic variation.
Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from approximate to 0.04 x 10(-6) to 0.4 x 10(-6)m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP-AChE binding is 4.2 x 10(-7)m indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer is the effective suppression of the cross-reactivity toward competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by i) the shape-specific MIP filter, ii) the propidium-SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid.
QuestionDoes eutrophication drive vegetation change in pine forests on nutrient deficient sites and thus lead to the homogenization of understorey species composition?
LocationForest area (1600ha) in the Lower Spreewald, Brandenburg, Germany.
MethodsResurvey of 77 semi-permanent plots after 45yr, including vascular plants, bryophytes and ground lichens. We applied multidimensional ordination of species composition, dissimilarity indices, mean Ellenberg indicator values and the concept of winner/loser species to identify vegetation change between years. Differential responses along a gradient of nutrient availability were analysed on the basis of initial vegetation type, reflecting topsoil N availability of plots.
ResultsSpecies composition changed strongly and overall shifted towards higher N and slightly lower light availability. Differences in vegetation change were related to initial vegetation type, with strongest compositional changes in the oligotrophic forest type, but strongest increase of nitrophilous species in the mesotrophic forest type. Despite an overall increase in species number, species composition was homogenized between study years due to the loss of species (mainly ground lichens) on the most oligotrophic sites.
ConclusionsThe response to N enrichment is confounded by canopy closure on the N-richest sites and probably by water limitation on N-poorest sites. The relative importance of atmospheric N deposition in the eutrophication effect is difficult to disentangle from natural humus accumulation after historical litter raking. However, the profound differences in species composition between study years across all forest types suggest that atmospheric N deposition contributes to the eutrophication, which drives understorey vegetation change and biotic homogenization in Central European Scots pine forests on nutrient deficient sites.
The nature of the interaction between prehistoric humans and their environment, especially the vegetation, has long been of interest. The Qinghai Lake Basin in North China is well-suited to exploring the interactions between prehistoric humans and vegetation in the Tibetan Plateau, because of the comparatively dense distribution of archaeological sites and the ecologically fragile environment. Previous pollen studies of Qinghai Lake have enabled a detailed reconstruction of the regional vegetation, but they have provided relatively little information on vegetation change within the Qinghai Lake watershed. To address the issue we conducted a pollen-based vegetation reconstruction for an archaeological site (YWY), located on the southern shore of Qinghai Lake. We used high temporal-resolution pollen records from the YWY site and from Qinghai Lake, spanning the interval since the last deglaciation (15.3 kyr BP to the present) to quantitatively reconstruct changes in the local and regional vegetation using Landscape Reconstruction Algorithm models. The results show that, since the late glacial, spruce forest grew at high altitudes in the surrounding mountains, while the lakeshore environment was occupied mainly by shrub-steppe. From the lateglacial to the middle Holocene, coniferous woodland began to expand downslope and reached the YWY site at 7.1 kyr BP. The living environment of the local small groups of Paleolithic-Epipaleolithic humans (during 15.3-13.1 kyr BP and 9-6.4 kyr BP) changed from shrub-steppe to coniferous forest-steppe. The pollen record shows no evidence of pronounced changes in the vegetation community corresponding to human activity. However, based on a comparison of the local and regional vegetation reconstructions, low values of biodiversity and a significant increase in two indicators of vegetation degradation, Chenopodiaceae and Rosaceae, suggest that prehistoric hunters-gatherers likely disturbed the local vegetation during 9.0-6.4 kyr BP. Our findings are a preliminary attempt to study human-environment interactions at Paleolithic-Epipaleolithic sites in the region, and they contribute to ongoing environmental archaeology research in the Tibetan Plateau.
Relationships between climate, species composition, and species richness are of particular importance for understanding how boreal ecosystems will respond to ongoing climate change. This study aims to reconstruct changes in terrestrial vegetation composition and taxa richness during the glacial Late Pleistocene and the interglacial Holocene in the sparsely studied southeastern Yakutia (Siberia) by using pollen and sedimentary ancient DNA (sedaDNA) records. Pollen and sedaDNA metabarcoding data using the trnL g and h markers were obtained from a sediment core from Lake Bolshoe Toko. Both proxies were used to reconstruct the vegetation composition, while metabarcoding data were also used to investigate changes in plant taxa richness. The combination of pollen and sedaDNA approaches allows a robust estimation of regional and local past terrestrial vegetation composition around Bolshoe Toko during the last similar to 35,000 years. Both proxies suggest that during the Late Pleistocene, southeastern Siberia was covered by open steppe-tundra dominated by graminoids and forbs with patches of shrubs, confirming that steppe-tundra extended far south in Siberia. Both proxies show disturbance at the transition between the Late Pleistocene and the Holocene suggesting a period with scarce vegetation, changes in the hydrochemical conditions in the lake, and in sedimentation rates. Both proxies document drastic changes in vegetation composition in the early Holocene with an increased number of trees and shrubs and the appearance of new tree taxa in the lake's vicinity. The sedaDNA method suggests that the Late Pleistocene steppe-tundra vegetation supported a higher number of terrestrial plant taxa than the forested Holocene. This could be explained, for example, by the "keystone herbivore" hypothesis, which suggests that Late Pleistocene megaherbivores were able to maintain a high plant diversity. This is discussed in the light of the data with the broadly accepted species-area hypothesis as steppe-tundra covered such an extensive area during the Late Pleistocene.
Ecological niche models (ENMs) are often used to investigate how climatic variables from known occurrence records can estimate potential species range distribution. Although climate-based ENMs provide critical baseline information, the inclusion of non-climatic predictors related to vegetation cover might generate more realistic scenarios. This assumption is particularly relevant for species with life-history traits related to forest habitats and sensitive to habitat loss and fragmentation. Here, we developed ENMs for 36 Atlantic Forest endemic birds considering two sets of predictor variables: (i) climatic variables only and (ii) climatic variables combined with the percentage of remaining native vegetation. We hypothesized that the inclusion of native vegetation data would decrease the potential range distribution of forest-dependent species by limiting their occurrence in regions harboring small areas of native vegetation habitats, despite otherwise favorable climatic conditions. We also expected that habitat restriction in the climate-vegetation models would be more pronounced for highly forest-dependent birds. The inclusion of vegetation data in the modeling procedures restricted the final distribution ranges of 22 out of 36 modeled species, while the 14 remaining presented an expansion of their ranges. We observed that species with high and medium forest dependency showed higher restriction in range size predictions between predictor sets than species with low forest dependency, which showed no alteration or range expansion. Overall, our results suggest that ENMs based on climatic and landscape variables may be a useful tool for conservationists to better understand the dynamic of bird species distributions in threatened and highly fragmented regions such as the Atlantic Forest hotspot.(c) 2021 Associacao Brasileira de Cie circumflex accent ncia Ecol ogica e Conservacao. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ ).
Shrub encroachment has far-reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning. We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compound-specific carbon (delta C-13) and deuterium (delta D) isotopes, bulk carbon isotopes (delta(13)Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution. We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n-alkane distributions and the delta C-13 and delta(13)Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our delta D record suggests physiological adaptations of woody species to higher atmospheric pCO(2) concentration and drought, our vegetation records reflect the impact of broad-scale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling-resistant taxa. In addition, grain-size and spore records suggest changes in the erodibility of soils because of reduced grass cover. Synthesis. We conclude that transitions to an encroached savanna state are supported by gradual environmental changes induced by management strategies, which affected the resilience of savanna ecosystems. In addition, feedback mechanisms that reflect the interplay between management legacies and climate change maintain the encroached state.
Ventilator-induced lung injury is aggravated by antibiotic mediated microbiota depletion in mice
(2018)
BackgroundAntibiotic exposure alters the microbiota, which can impact the inflammatory immune responses. Critically ill patients frequently receive antibiotic treatment and are often subjected to mechanical ventilation, which may induce local and systemic inflammatory responses and development of ventilator-induced lung injury (VILI). The aim of this study was to investigate whether disruption of the microbiota by antibiotic therapy prior to mechanical ventilation affects pulmonary inflammatory responses and thereby the development of VILI.MethodsMice underwent 6-8weeks of enteral antibiotic combination treatment until absence of cultivable bacteria in fecal samples was confirmed. Control mice were housed equally throughout this period. VILI was induced 3 days after completing the antibiotic treatment protocol, by high tidal volume (HTV) ventilation (34ml/kg; positive end-expiratory pressure=2 cmH(2)O) for 4h. Differences in lung function, oxygenation index, pulmonary vascular leakage, macroscopic assessment of lung injury, and leukocyte and lymphocyte differentiation were assessed. Control groups of mice ventilated with low tidal volume and non-ventilated mice were analyzed accordingly.ResultsAntibiotic-induced microbiota depletion prior to HTV ventilation led to aggravation of VILI, as shown by increased pulmonary permeability, increased oxygenation index, decreased pulmonary compliance, enhanced macroscopic lung injury, and increased cytokine/chemokine levels in lung homogenates.ConclusionsDepletion of the microbiota by broad-spectrum antibiotics prior to HTV ventilation renders mice more susceptible to developing VILI, which could be clinically relevant for critically ill patients frequently receiving broad-spectrum antibiotics.