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Ecosystems are generally linked via fluxes of nutrients and energy across their boundaries. For example, freshwater ecosystems in temperate regions may receive significant inputs of terrestrially derived carbon via autumnal leaf litter. This terrestrial particulate organic carbon (POC) is hypothesized to subsidize animal production in lakes, but direct evidence is still lacking. We divided two small eutrophic lakes each into two sections and added isotopically distinct maize litter to the treatment sections to simulate increased terrestrial POC inputs via leaf litter in autumn. We quantified the reliance of aquatic consumers on terrestrial resources (allochthony) in the year subsequent to POC additions by applying mixing models of stable isotopes. We also estimated lake-wide carbon (C) balances to calculate the C flow to the production of the major aquatic consumer groups: benthic macroinvertebrates, crustacean zooplankton, and fish. The sum of secondary production of crustaceans and benthic macroinvertebrates supported by terrestrial POC was higher in the treatment sections of both lakes. In contrast, total secondary and tertiary production (supported by both autochthonous and allochthonous C) was higher in the reference than in the treatment sections of both lakes. Average aquatic consumer allochthony per lake section was 27-40%, although terrestrial POC contributed less than about 10% to total organic C supply to the lakes. The production of aquatic consumers incorporated less than 5% of the total organic C supply in both lakes, indicating a low ecological efficiency. We suggest that the consumption of terrestrial POC by aquatic consumers facilitates a strong coupling with the terrestrial environment. However, the high autochthonous production and the large pool of autochthonous detritus in these nutrient-rich lakes make terrestrial POC quantitatively unimportant for the C flows within food webs.
Background In view of the ongoing debate on "chronic malnutrition" and the concept of "stunting" as "a better measure than underweight of the cumulative effects of undernutrition and infection (WHO)", we translate, briefly comment and republish three seminal historic papers on catch-up growth following re-feeding after severe food restriction of German children during and after World War I. The observations were published in 1920 and 1922, and appear to be of particular interest to the modern nutritionist. Results The papers of Abderhalden (1920) and Bloch (1920) describe German children of all social strata who were born shortly before World War I, and raised in apparently "normal" families. After severe long-standing undernutrition, they participated in an international charity program. They experienced exceptional catch-up growth in height of 3-5 cm within 6-8 weeks. Goldstein (1922) observed 512 orphans and children from underprivileged families. Goldstein described very different growth patterns. These children were much shorter (mean height between -2.0 and -2.8 SDS, modern WHO reference). They mostly failed to catch-up in height, but tended to excessively increase in weight particularly during adolescence.
WIP proteins form a plant specific subfamily of C2H2 zinc finger (ZF) proteins. In this study, we functionally characterized the WIP domain, which consists of four ZF motifs, and discuss molecular functions for WIP proteins. Mutations in each of the ZFs lead to loss of function of the TT1/WIP1 protein in Arabiopsis thaliana. SV40 type nuclear localisation signals were detected in two of the ZFs and functionally characterized using GFP fusions as well as new mutant alleles identified by TILLING. Promoter swap experiments showed that selected WIP proteins are partially able to take over TT1 function. Activity of the AtBAN promoter, a potential TT1 target, could be increased by the addition of TT1 to the TT2-TT8-TTG1 regulatory complex.
Neben dem Habitatverlust gelten Konsequenzen der Habitatfragmentierung seit den 1990er Jahren als wesentliche Ursache der Gefaehrdung von Pflanzen und stehen damit nun auch im Fokus des botanischen Artenschutzes. Der vorliegende Beitrag gibt einen ueberblick ueber den Stand der populationsbiologischen und genetischen Forschung und versucht abzuschaetzen, welche Bedeutung Habitatfragmentierung und die dadurch entstehenden kleinen, isolierten Populationen auf heimische Pflanzenarten haben koennen. Als wesentliche und offenbar sehr weit verbreitete negative Effekte werden Zufallsereignisse, Randeffekte, Bestaeuberlimitierung, Gendrift und Inzuchtdepression identifiziert. Zusammen mit verringerter Habitatqualitaet durch Eutrophierung, Entwaesserung oder Nutzungsaenderung wirken sie zumeist negativ auf die Fitness der Individuen und Populationen und erhoehen so deren Aussterberisiko. Dieser negative Effekt kleiner Populationen auf die individuelle Fitness wird unabhaengig von der Ursache als Allee-Effekt bezeichnet. Eine durch einen Biotopverbund gefoerderte Metapopulationsdynamik kann das dauerhafte Aussterben von Pflanzenpopulationen verhindern und mindert die negativen genetischen Effekte der Habitatfragmentierung ueber einen erhoehten Genfluss durch Pollen und Samen. Die bisherigen wissenschaftlichen Studien in Mitteleuropa beruhen allerdings in ueberproportionaler Weise auf bestimmten Pflanzenfamilien (Gentianaceae, Primulaceae), Habitaten (Trocken- und Magerrasen, Wirtschaftsgruenland), insekten- und obligat fremdbestaeubten sowie weitgehend auf sexuelle Fortpflanzung angewiesenen Arten, waehrend etwa ueber Grasartige, Ruderalpflanzen, wind- und selbstbestaeubte sowie an vegetative Fortpflanzung angepasste Arten nur wenige Erkenntnisse vorliegen. Gerade diese und Pflanzenarten mit hohem Ausbreitungspotenzial muessen aber nach derzeitigem Wissensstand als weniger sensitiv gegenueber Habitatfragmentierung eingestuft werden. Auf diesen Befunden aufbauend werden fuer die Naturschutzpraxis Biotoptypen hinsichtlich ihrer Sensitivitaet gegenueber Habitatfragmentierung klassifiziert und ein auf biologischen Merkmalen basierender Kriterienkatalog zur Auswahl von Zielarten des Biotopverbunds vorgestellt. Schließlich wird eroertert, was bei Maßnahmen zur Regeneration kleiner bzw. bereits ausgestorbener Populationen zu beachten ist, und es werden allgemeine Folgerungen zur Ausgestaltung eines Biotopverbundskonzepts fuer Pflanzen gezogen.
Welcome to the dark side
(2022)
Differences in natural light conditions caused by changes in moonlight are known to affect perceived predation risk in many nocturnal prey species. As artificial light at night (ALAN) is steadily increasing in space and intensity, it has the potential to change movement and foraging behavior of many species as it might increase perceived predation risk and mask natural light cycles. We investigated if partial nighttime illumination leads to changes in foraging behavior during the night and the subsequent day in a small mammal and whether these changes are related to animal personalities. We subjected bank voles to partial nighttime illumination in a foraging landscape under laboratory conditions and in large grassland enclosures under near natural conditions. We measured giving-up density of food in illuminated and dark artificial seed patches and video recorded the movement of animals. While animals reduced number of visits to illuminated seed patches at night, they increased visits to these patches at the following day compared to dark seed patches. Overall, bold individuals had lower giving-up densities than shy individuals but this difference increased at day in formerly illuminated seed patches. Small mammals thus showed carry-over effects on daytime foraging behavior due to ALAN, i.e., nocturnal illumination has the potential to affect intra- and interspecific interactions during both night and day with possible changes in personality structure within populations and altered predator-prey dynamics.
Welcome to the Dark Side
(2022)
Differences in natural light conditions caused by changes in moonlight are known to affect perceived predation risk in many nocturnal prey species. As artificial light at night (ALAN) is steadily increasing in space and intensity, it has the potential to change movement and foraging behavior of many species as it might increase perceived predation risk and mask natural light cycles. We investigated if partial nighttime illumination leads to changes in foraging behavior during the night and the subsequent day in a small mammal and whether these changes are related to animal personalities. We subjected bank voles to partial nighttime illumination in a foraging landscape under laboratory conditions and in large grassland enclosures under near natural conditions. We measured giving-up density of food in illuminated and dark artificial seed patches and video recorded the movement of animals. While animals reduced number of visits to illuminated seed patches at night, they increased visits to these patches at the following day compared to dark seed patches. Overall, bold individuals had lower giving-up densities than shy individuals but this difference increased at day in formerly illuminated seed patches. Small mammals thus showed carry-over effects on daytime foraging behavior due to ALAN, i.e., nocturnal illumination has the potential to affect intra- and interspecific interactions during both night and day with possible changes in personality structure within populations and altered predator-prey dynamics.
Urban forests fulfil various functions, among them the restoration process and aesthetical needs of urban residents. This article reflects the attitudes towards different managed forests on the one hand and their influence on psychological well-being on the other. Results of empirical approaches from both fields show some inconsistency, suggesting that people have a more positive attitude towards wild forest areas, while the effect on well-being is more positive after a walk in tended forest areas. A discussion follows on the link between perception and the effect of urban forests. An outlook on necessary research reveals the need for longitudinal research. The article concludes by showing management implications.
What Colin Reynolds could tell us about nutrient limitation, N:P ratios and eutrophication control
(2020)
Colin Reynolds exquisitely consolidated our understanding of driving forces shaping phytoplankton communities and those setting the upper limit to biomass yield, with limitation typically shifting from light in winter to phosphorus in spring. Nonetheless, co-limitation is frequently postulated from enhanced growth responses to enrichments with both N and P or from N:P ranging around the Redfield ratio, concluding a need to reduce both N and P in order to mitigate eutrophication. Here, we review the current understanding of limitation through N and P and of co-limitation. We conclude that Reynolds is still correct: (i) Liebig's law of the minimum holds and reducing P is sufficient, provided concentrations achieved are low enough; (ii) analyses of nutrient limitation need to exclude evidently non-limiting situations, i.e. where soluble P exceeds 3-10 mu g/l, dissolved N exceeds 100-130 mu g/l and total P and N support high biomass levels with self-shading causing light limitation; (iii) additionally decreasing N to limiting concentrations may be useful in specific situations (e.g. shallow waterbodies with high internal P and pronounced denitrification); (iv) management decisions require local, situation-specific assessments. The value of research on stoichiometry and co-limitation lies in promoting our understanding of phytoplankton ecophysiology and community ecology.
What does stunting tell us?
(2023)
Stunting is commonly linked with undernutrition. Yet, already after World War I, German pediatricians questioned this link and stated that no association exists between nutrition and height. Recent analyses within different populations of Low- and middle-income countries with high rates of stunted children failed to support the assumption that stunted children have a low BMI and skinfold sickness as signs of severe caloric deficiency. So, stunting is not a synonym of malnutrition. Parental education level has a positive influence on body height in stunted populations, e.g., in India and in Indonesia. Socially disadvantaged children tend to be shorter and lighter than children from affluent families.
Humans are social mammals; they regulate growth similar to other social mammals. Also in humans, body height is strongly associated with the position within the social hierarchy, reflecting the personal and group-specific social, economic, political, and emotional environment. These non-nutritional impact factors on growth are summarized by the concept of SEPE (Social-Economic-Political-Emotional) factors. SEPE reflects on prestige, dominance-subordination, social identity, and ego motivation of individuals and social groups.
ObjectivesAge at menarche is one of the most important factors when observing growth and development. The aim of this study was to assess the temporal pattern in variability of menarcheal age for a historic Swiss population from the 19th and 20th centuries. ResultsMean menarcheal age declined from 17.34 years (n=358) around 1830 to 13.80 years (n=141) around 1950. Within-cohort variance decreased from 7.5 to 2.1 year(2). Skewness was negatively correlated with birth year (r=-0.58). ConclusionThis study provided evidence for a secular trend in various statistical parameters for age at menarche since the 19th century. Furthermore, the results of the analysis of temporal pattern in variability revealed that the secular trend in menarcheal age happened in two phases. Am. J. Hum. Biol. 28:705-713, 2016. (c) 2016 Wiley Periodicals, Inc.
* 1. Large female insects usually have high potential fecundity. Therefore selection should favour an increase in body size given that these females get opportunities to realize their potential advantage by maturing and laying more eggs. However, ectotherm physiology is strongly temperature-dependent, and activities are carried out sufficiently only within certain temperature ranges. Thus it remains unclear if the fecundity advantage of a large size is fully realized in natural environments, where thermal conditions are limiting. * 2. Insect fecundity might be limited by temperature at two levels; first eggs need to mature, and then the female needs time for strategic ovipositing of the egg. Since a female cannot foresee the number of oviposition opportunities that she will encounter on a given day, the optimal rate of egg maturation will be governed by trade-offs associated with egg- and time-limited oviposition. As females of different sizes will have different amounts of body reserves, size-dependent allocation trade-offs between the mother"s condition and her egg production might be expected. * 3. In the temperate butterfly Pararge aegeria, the time and temperature dependence of oviposition and egg maturation, and the interrelatedness of these two processes were investigated in a series of laboratory experiments, allowing a decoupling of the time budgets for the respective processes. * 4. The results show that realized fecundity of this species can be limited by both the temperature dependence of egg maturation and oviposition under certain thermal regimes. Furthermore, rates of oviposition and egg maturation seemed to have regulatory effects upon each other. Early reproductive output was correlated with short life span, indicating a cost of reproduction. Finally, large females matured more eggs than small females when deprived of oviposition opportunities. Thus, the optimal allocation of resources to egg production seems dependent on female size. * 5. This study highlights the complexity of processes underlying rates of egg maturation and oviposition in ectotherms under natural conditions. We further discuss the importance of temperature variation for egg- vs. time-limited fecundity and the consequences for the evolution of female body size in insects.
Gating of K+ and other ion channels is 'hard-wired' within the channel protein. So it remains a puzzle how closely related channels in plants can show an unusually diverse range of biophysical properties. Gating of these channels lies at the heart of K+ mineral nutrition, signalling, abiotic and biotic stress responses in plants. Thus, our knowledge of the molecular mechanics underpinning K+ channel gating will be important for rational engineering of related traits in agricultural crops. Several key studies have added significantly to our understanding of channel gating in plants and have challenged current thinking about analogous processes found in animal K+ channels. Such studies highlight how much of K+ channel gating remains to be explored in plants.
Trait-based studies have become extremely common in plant ecology. Trait-based approaches often rely on the tacit assumption that intraspecific trait variability (ITV) is negligible compared to interspecific variability, so that species can be characterized by mean trait values. Yet, numerous recent studies have challenged this assumption by showing that ITV significantly affects various ecological processes. Accounting for ITV may thus strengthen trait-based approaches, but measuring trait values on a large number of individuals per species and site is not feasible. Therefore, it is important and timely to synthesize existing knowledge on ITV in order to (1) decide critically when ITV should be considered, and (2) establish methods for incorporating this variability. Here we propose a practical set of rules to identify circumstances under which ITV should be accounted for. We formulate a spatial trait variance partitioning hypothesis to highlight the spatial scales at which ITV cannot be ignored in ecological studies. We then refine a set of four consecutive questions on the research question, the spatial scale, the sampling design, and the type of studied traits, to determine case-by-case if a given study should quantify ITV and test its effects. We review methods for quantifying ITV and develop a step-by-step guideline to design and interpret simulation studies that test for the importance of ITV. Even in the absence of quantitative knowledge on ITV, its effects can be assessed by varying trait values within species within realistic bounds around the known mean values. We finish with a discussion of future requirements to further incorporate ITV within trait-based approaches. This paper thus delineates a general framework to account for ITV and suggests a direction towards a more quantitative trait-based ecology.
QuestionBelow-ground processes are key determinants of above-ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above-ground diversity patterns, bypassing below-ground plant diversity stored in seed banks. As seed banks may shape above-ground plant communities, we question whether concurrently analysing the above- and below-ground species assemblages may potentially enhance our understanding of community responses to environmental variation. LocationTemperate deciduous forests along a 2000km latitudinal gradient in NW Europe. MethodsHerb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer-seed bank community. ResultsSeed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and -diversity of the combined herb layer-seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover. ConclusionsThe seed bank is a below-ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co-exist as a single community by means of the so-called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above- and below-ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.
Earthworms affect various soil ecosystem processes in their role as ecosystem engineers. The spatial distribution of earthworms determines the spatial distribution of their functional effects. In particular, earthworm-induced macropore networks may act as preferential flow pathways. In this research we aimed to determine earthworm distributions at the catchment scale with species distribution models (SDMs). We used land-use types, temporally invariant topography-related variables and plot-scale soil characteristics such as pH and organic matter content. We used data from spring 2013 to estimate probability distributions of the occurrence of ten earthworm species. To assess the robustness of these models, we tested temporal transferability by evaluating the accuracy of predictions from the models derived for the spring data with the predictions from data of two other field surveys in autumn 2012 and 2013. In addition, we compared the performance of SDMs based (i) on temporally varying plot-scale predictor variables with (ii) those based on temporally invariant catchment-scale predictors. Models based on catchment-scale predictors, especially land use and slope, experience a small loss of predictive performance only compared with plot-scale SDMs but have greater temporal transferability. Earthworm distribution maps derived from this kind of SDM are a prerequisite for understanding the spatial distribution patterns of functional effects related to earthworms.
Semi-natural habitats (SNHs) are becoming increasingly scarce in modern agricultural landscapes. This may reduce natural ecosystem services such as pest control with its putatively positive effect on crop production. In agreement with other studies, we recently reported wheat yield reductions at field borders which were linked to the type of SNH and the distance to the border. In this experimental landscape-wide study, we asked whether these yield losses have a biotic origin while analyzing fungal seed and fungal leaf pathogens, herbivory of cereal leaf beetles, and weed cover as hypothesized mediators between SNHs and yield. We established experimental winter wheat plots of a single variety within conventionally managed wheat fields at fixed distances either to a hedgerow or to an in-field kettle hole. For each plot, we recorded the fungal infection rate on seeds, fungal infection and herbivory rates on leaves, and weed cover. Using several generalized linear mixed-effects models as well as a structural equation model, we tested the effects of SNHs at a field scale (SNH type and distance to SNH) and at a landscape scale (percentage and diversity of SNHs within a 1000-m radius). In the dry year of 2016, we detected one putative biotic culprit: Weed cover was negatively associated with yield values at a 1-m and 5-m distance from the field border with a SNH. None of the fungal and insect pests, however, significantly affected yield, neither solely nor depending on type of or distance to a SNH. However, the pest groups themselves responded differently to SNH at the field scale and at the landscape scale. Our findings highlight that crop losses at field borders may be caused by biotic culprits; however, their negative impact seems weak and is putatively reduced by conventional farming practices.