Реакція української інтелігенції на Голокост: моделі ситуативної поведінки

The article regards the types of behawor attitude of the Ukranian intellegensy to the Holocaust, which was realigeb by nazi on the Kiev region

Dispersal of Plants by Waterbirds

The widespread distribution of fresh-water plants and of the lower animals, whether retaining the same identical form or in some degree modified, I believe mainly depends on the wide dispersal of their seeds and eggs by animals, more especially by fresh-water birds, which have large powers of flight, and naturally travel from one to another and often distant piece of water. — Charles Darwin (1859)Peer reviewe

Seed dispersal by dabbling ducks: an overlooked dispersal pathway for a broad spectrum of plant species

1. Dabbling ducks (Anatinae) are omnivorous birds that are widespread, numerous, highly mobile and often migratory, and therefore have great potential for (long distance) dispersal of other organisms, including plants. However, their ability to act as plant dispersal vectors has received little attention compared to frugivores and is often assumed to be relevant only for wetland species. 2. To evaluate the potential for plant dispersal by dabbling ducks, we collated and analysed existing data. We identified all plant species whose seeds have been recorded in the diets of the seven dabbling duck (Anas) species in the Western Palaearctic, as reported from gut content analyses. We then analysed the habitats and traits of these plant species to identify general patterns, and related these to data on gut passage survival and duck movements. 3. A large number of plant species (> 445 species of 189 genera and 57 families) have been recorded in the diet of dabbling ducks. These plant species represent a very wide range of habitats, including almost the full range of site fertility, moisture and light conditions, excluding only very dry and deeply shaded habitats. The ducks prefer seeds of intermediate sizes (1–10 mm3), which have good chances to survive gut passage, but also ingest smaller and larger seeds. Ingested seeds represent a wide range of dispersal syndromes, including fleshy fruits. Many species (62%) were not previously considered animal- dispersed in plant data bases, and 66% were not identified as bird-dispersed. Rarefaction analyses suggest that our analysis still greatly underestimates the total number of plant species ingested. 4. Synthesis. Dabbling ducks do not exclusively ingest seeds of wetland plants, which make up only 40% of the ingested species. Rather, they feed opportunistically on a wide cross-section of plant species available across the landscapes they inhabit. Given the millions of ducks, the hundreds to thousands of seeds ingested per individual on a daily basis, and known gut passage survival rates, this results in vast numbers of seeds dispersed by ducks per day. Internal seed dispersal by dabbling ducks appears to be a major dispersal pathway for a far broader spectrum of plant species than previously consideredPeer reviewe

Weak negative associations between avian influenza virus infection and movement behaviour in a key host species, the mallard Anas platyrhynchos

Animal movements may contribute to the spread of pathogens. In the case of avian influenza virus, [migratory] birds have been suggested to play a role in the spread of some highly pathogenic strains (e.g. H5N1, H5N8), as well as their low pathogenic precursors which circulate naturally in wild birds. For a better understanding of the emergence and spread of both highly pathogenic (HPAIV) and low pathogenic avian influenza virus (LPAIV), the potential effects of LPAIVs on bird movement need to be evaluated. In a key host species, the mallard Anas platyrhynchos, we tested whether LPAIV infection status affected daily local ( 100 m) movements by comparing movement behaviour 1) within individuals (captured and sampled at two time points) and 2) between individuals (captured and sampled at one time point). We fitted free-living adult males with GPS loggers throughout the autumn LPAIV infection peak, and sampled them for LPAIV infection at logger deployment and at logger removal on recapture. Within individuals, we found no association between LPAIV infection and daily local and regional movements. Among individuals, daily regional movements of LPAIV infected mallards in the last days of tracking were lower than those of non-infected birds. Moreover, these regional movements of LPAIV infected birds were additionally reduced by poor weather conditions (i.e. increased wind and/or precipitation and lower temperatures). Local movements of LPAIV infected birds in t

Seed dispersal by waterbirds: a mechanistic understanding by simulating avian digestion

Waterbirds disperse plant species via ingestion and egestion of seeds (endozoochory). However, our understanding about the regulating effects of seed traits, underlying mechanisms and possible (co)evolutionary processes is limited by our traditional reliance on data from feeding experiments with living waterbirds. Here, we overcome these limitations by developing and applying a new bioassay that realistically simulates digestive processes for Anseriformes waterbirds. We test three hypotheses: 1) seed survival and germination are most affected by mechanical digestion in the waterbird gizzard; 2) seed size, hardness, imbibition and shape regulate seed survival; and 3) plants growing in aquatic habitats benefit most from endozoochory by waterbirds. Experiments with 28 200 seeds of 48 plant species demonstrated species-specific seed survival that was entirely determined by digestion in the avian gizzard. Intestinal digestion did not affect seed survival but affected seed establishment (germinability and germination time) for 21% of the species. Large, hard seeds survived the simulations the best, in contrast to generally higher seed survival for smaller seeds during in vivo experiments. This mechanistically explains that small seeds escape digestive processes rather than being inherently more resistant (the ‘escape mechanism'), while large seeds are retained until fully digested or regurgitated (the ‘resistance and regurgitation mechanism'). Plants growing in wetter habitats had similar seed survival, but digestive processes stimulated their germinability and accelerated their germination more than for terrestrial plants. This indicates a relative advantage of endozoochory for plant species growing in wet habitats, possibly reflecting a co-evolutionary response related to dormancy breaking by gut passage. Simulating seed gut passage using a bioassay allowed establishing mechanisms and identifying relevant seed traits involved in seed dispersal by waterbirds. This information enhances our understanding of how animal species shape plant species distributions, which is extremely relevant now that current anthropogenic pressures already severely impact plant dispersal capacities

Environmental morphing enables informed dispersal of the dandelion diaspore

Animal migration is highly sensitised to environmental cues, but plant dispersal is considered largely passive. The common dandelion, Taraxacum officinale, bears an intricate haired pappus facilitating flight. The pappus enables the formation of a separated vortex ring during flight; however, the pappus structure is not static but reversibly changes shape by closing in response to moisture. We hypothesised that this leads to changed dispersal properties in response to environmental conditions. Using wind tunnel experiments for flow visualisation, particle image velocimetry, and flight tests we characterised the fluid mechanics effects of the pappus morphing. We also modelled dispersal to understand the impact of pappus morphing on diaspore distribution. Pappus morphing dramatically alters the fluid mechanics of diaspore flight. We found that when the pappus closes in moist conditions, the drag coefficient decreases and thus the falling velocity is greatly increased. Detachment of diaspores from the parent plant also substantially decreases. The change in detachment when the pappus closes increases dispersal distances by reducing diaspore release when wind speeds are low. We propose that moisture-dependent pappus-morphing is a form of informed dispersal allowing rapid responses to changing conditions

Space resource utilization of dominant species integrates abundance- and functional-based processes for better predictions of plant diversity dynamics

Sustainable ecosystem management relies on our ability to predict changes in plant diversity and to understand the underlying mechanisms. Empirical evidence demonstrates that abundance- and functional-based processes simultaneously explain the loss of plant diversity in response to human activities. Recently, a novel indicator based on percent cover (CoverD) and maximum height (HeightD) of the dominant plant species – space resource utilization (SRUD) – has proven to give robust and better predictions of plant diversity dynamics than community biomass. Whether the superior predictive ability of SRUD is due to its capacity to simultaneously capture abundance- and functional-based processes remains unknown. Here, we tested this hypothesis by quantifying mechanistic links between changes in SRUD and biodiversity in response to nutrients and herbivores. Furthermore, we assessed the relative contribution of dominant, intermediate and rare species to reduced density of individuals by combining null model analysis with field experiments. We found that SRUD successfully captured changes in ground-level light availability and changes in the number of individuals to predict plant diversity dynamics, and each of CoverD and HeightD partly and independently contributed to both processes. Comparative results from null model analysis and field experiments confirmed that individual losses of dominant, intermediate and rare species followed non-random processes. Specifically, compared with random loss process, rare species lost proportionally more individuals and thus disproportionately contributed to species loss, while dominant and intermediate species lost less. Our results demonstrate that SRUD captures both abundance- and functional-based processes thus explaining why SRUD provides more accurate predictions of changes in species diversity. Given that rare species can play an important role in shaping community structure, resisting against invasion, impacting higher trophic levels and providing multiple ecosystem functions, reducing the SRU of dominant species could alleviate the risk of exclusion of rare species by mitigating abundance- and functional-based competition processes

Conservation of birds in fragmented landscapes requires protected areas

For successful conservation of biodiversity, it is vital to know whether protected areas in increasingly fragmented landscapes effectively safeguard species. However, how large habitat fragments must be, and what level of protection is required to sustain species, remains poorly known. We compiled a global dataset on almost 2000 bird species in 741 forest fragments varying in size and protection status, and show that protection is associated with higher bird occurrence, especially for threatened species. Protection becomes increasingly effective with increasing size of forest fragments. For forest fragments >50 ha our results show that strict protection (International Union for Conservation of Nature [IUCN] categories I–IV) is strongly associated with higher bird occurrence, whereas fragments had to be at least 175 ha for moderate protection (IUCN categories V and VI) to have a positive effect. This meta-analysis quantifies the importance of fragment size, protection status, and their interaction for the conservation of bird species communities, and stresses that protection should not be limited to large pristine areas

A seed dispersal effectiveness framework across the mutualism–antagonism continuum

Many angiosperms rely on vertebrates for seed dispersal via gut passage, an interaction that has been traditionally classified as a mutualism. The seed dispersal effectiveness (SDE) framework provides a mechanistic approach to evaluate evolutionary and ecological characteristics of animal-mediated seed dispersal, by synthesising the quantity and the quality of the dispersal that a plant species receives from each of its animal dispersers. However, the application of the SDE framework has been largely restricted to plant–frugivore interactions, whereas animal-mediated seed dispersal results from plant–disperser interactions that cover a continuum from pure mutualisms to antagonisms. This biases ecological and evolutionary knowledge on plant–disperser interactions. Here, we propose an extended SDE framework (‘eSDE') that allows comparing plant–disperser interactions in the full mutualism–antagonism continuum ranging from pure mutualisms (frugivores) to conditional mutualisms (scatter-hoarding granivores and folivores) and antagonisms (pure granivores). We present the eSDE framework, and use examples to illustrate how it can be applied to compare effectiveness among plant–disperser interaction types. Our initial comparison based on available data suggests that vertebrate species differ more in the number of seeds they deposit away from the mother plant (quantity), than in the effects such dispersal processes have on seed fate (quality). Scatter-hoarding granivores provide the most effective dispersal due to high removal rates, closely followed by frugivores due to high deposition rates. Folivores and pure granivores provide low quantity dispersal, but of high and moderate quality, respectively. These early comparative insights illustrate the necessity and usefulness of more standardized data collection protocols, for which we provide recommendations. Applying the eSDE framework can reveal broad-scale patterns across and within plant–disperser interaction types, which will advance our evolutionary understanding of plant–animal interactions. This will provide new insights into the consequence of anthropogenic impacts on vertebrate-mediated seed dispersal in a world in which plant–animal interactions are increasingly threatened

Non-random seed abscission, long-distance wind dispersal and plant migration rates

1. In plants, long-distance dispersal (LDD) is a widespread phenomenon of great importance, especially in spatial dynamics such as in metapopulations, invasions and migration. Much has become known about the mechanisms underlying LDD by wind, but selective release mechanisms have received little attention. Recent papers call for particular effort in clarification of the seed release stage of the dispersal process, which is our aim here. 2. We studied non-random seed release at a range of spatial scales, from the individual plant to species' spatial dynamics. We did this by combining wind tunnel experiments, field trap data and simulation and analytical models, using two common wind-dispersed heathland plants (Calluna vulgaris and Erica cinerea) as study species. 3. In both species, seed release from the plant increases with increasing wind velocity. There is a minimum release threshold, above which the probability of seed release increases with increasing wind velocity. The drag caused by the wind is the motive force for seed release. 4. Simulations of seed dispersal with non-random seed release match measured dispersal kernels better, especially in the tails, than 'conventional' simulations with random seed release. Seed release during gusts gives the most realistic kernel. This result matches previous findings that seeds are released primarily at the start of gusts and during turbulent wind flow. 5. Dispersal kernels assuming non-random seed release had large impacts on analytically modelled population migration rates. Wavespeeds assuming seed release during gusts were, on average, more than double those assuming random seed release. Increases in wavespeeds under different seed release assumptions were due mostly to increases in the tail of the dispersal kernel. 6. Synthesis. This study shows how the small-scale process of a seed being released from the plant could affect the large-scale spatial dynamics of plant species in landscapes. The mechanism of non-random seed release, i.e., seed release during gusts, is an important mechanism for attaining LDD by wind. As such, non-random seed release influences landscape-scale species dynamics such as invasions and migratio