89,165 research outputs found
Ueber einige Methoden zur Bestimmung der bei der Diffusion einer Salzlösung in das reine Lösungsmittel auftretende Constante
No full textvon Th. Simler und H. WildSonderdruck aus: Annalen der Physik und Chemie, Bd. C, Nr. 2, S. 217-235Ergänzung zum Title: " (Vortrag, gehalten in der Naturforschenden Gesellschaft zu Zürich den 15. Dec. 1856 von H. Wild)
Ethnobotanical investigation of 'wild' food plants used by rice farmers in Kalasin, Northeast Thailand
Full text linkAbstract Background Wild food plants are a critical component in the subsistence system of rice farmers in Northeast Thailand. One of the important characteristics of wild plant foods among farming households is that the main collection locations are increasingly from anthropogenic ecosystems such as agricultural areas rather than pristine ecosystems. This paper provides selected results from a study of wild food conducted in several villages in Northeast Thailand. A complete botanical inventory of wild food plants from these communities and surrounding areas is provided including their diversity of growth forms, the different anthropogenic locations were these species grow and the multiplicity of uses they have. Methods Data was collected using focus groups and key informant interviews with women locally recognized as knowledgeable about contemporarily gathered plants. Plant species were identified by local taxonomists. Results A total of 87 wild food plants, belonging to 47 families were reported, mainly trees, herbs (terrestrial and aquatic) and climbers. Rice fields constitute the most important growth location where 70% of the plants are found, followed by secondary woody areas and home gardens. The majority of species (80%) can be found in multiple growth locations, which is partly explained by villagers moving selected species from one place to another and engaging in different degrees of management. Wild food plants have multiple edible parts varying from reproductive structures to vegetative organs. More than two thirds of species are reported as having diverse additional uses and more than half of them are also regarded as medicine. Conclusions This study shows the remarkable importance of anthropogenic areas in providing wild food plants. This is reflected in the great diversity of species found, contributing to the food and nutritional security of rice farmers in Northeast Thailand.</p
Competition between wild and captive-bred Penaeus plebejus and implications for stock enhancement
Full text linkThe mechanisms that drive density dependence are rarely studied in the applied context of population management. We examined the potential for competition for food and shelter and the resulting demographic density dependence to influence how well populations of the eastern king prawn Penaeus plebejus Hess can recover following marine stock enhancement programmes in which captive-bred juveniles are released into the wild. Specifically, manipulative laboratory experiments were used to quantify the differential effects of competition for food and competition for shelter on survival of wild and captive-bred P. plebejus as densities were increased and as each category of P. plebejus (wild or captive-bred) was supplemented with the alternate category. Increasing population densities when food and shelter were limited lowered survival for both categories. When food was limited, survival of both categories was unaffected by addition of the alternative category. Adding wild P. plebejus to their captive-bred counterparts when shelter was limited under laboratory conditions resulted in significantly higher mortality in captive-bred individuals. In contrast, adding captive-bred P. plebejus to wild individuals under these conditions did not affect wild P. plebejus. We conclude that if the current results can be extended to wild conditions, competition for shelter may lead to the loss of captive-bred P. plebejus, thereby reducing the intended outcomes of stock enhancement. This highlights the importance of investigating interactions between wild and captive-bred animals prior to stock enhancement to predict long-term outcomes and identify situations where stock enhancement could be an effective response to the loss of populations or recruitment limitation
Preventing wild boar "Sus scrofa" damage - considerations for wild boar management in highly fragmented agroecosystems
Full text linkDuring the last three decades wild boar populations have grown rapidly and the range of the species has increased steadily, covering almost the whole European continent today. The huge spread of the wild boar and the high population densities pose major problems, particularly to agriculture. Wild boars cause considerable damage to fields and grassland, but also pose a potentially high threat to livestock, as carrier of the pathogen of the classical swine fever, which may be transmitted to domestic pigs and can cause huge losses. To prevent economic problems by high wild boar populations, an effective wild boar management has to be established. Besides the regulation of the populations by means of hunting, vulnerable crop fields have to be protected adequately. Crop protection is usually achieved by the use of electric fences. Alternatively, various methods are available that claim effective deterrence of wild boars, however, most of which lacking scientific proof of effectiveness.
This thesis, based on a field study conducted in the Canton Basel-Land, northwestern Switzerland, presents research results on the effectiveness of three different deterrent systems: solar-powered blinkers, an odour repellent, and a gustatory repellent. The aims of the study were: (1) to investigate three means to deter wild boars from agricultural land representative for other deterrents based on optic, olfactory, or gustatory effects; (2) to provide relevant and evidence-based data, which contribute to the policy and practice of wild boar management and damage prevention in the Canton Basel-Land, also applicable to other regions. I discussed the results in a broader context, also considering the role of hunting in damage prevention.
Solar blinkers and the odour repellent, which were investigated at baited luring sites, reduced the probability of wild boar visits by 8.1% and by 0.4% respectively. Both deterrents were not effective in preventing wild boars from accessing the lure food. Additionally, we did not find any initial deterrence effect. The gustatory repellent, which was investigated in experimental fields, did not have a significant effect on the frequency of damage events. Although we observed a slight trend towards a damage reduction, the results show, that the repellent was not able to prevent damage. We further could not detect any area avoidance by the wild boars as a response to the repellent.
The present study revealed, that none of the deterrents investigated was able to prevent wild boars from entering the experimental sites. Hence the deterrents in question are no effective means for field protection. Moreover, I suggest that any other deterrent basing on startling response, neophobia, fear-evocation, or conditioned avoidance would not be effective in preventing wild boars from entering agricultural land. To date, the only recommendable means for damage prevention is the electric fence, which should be taken into account by the responsible authorities. Based on the findings of the present study, farmers must be discouraged from the use of other deterrents than electric fences to protect their fields. Additionally, damage compensation should be subject to the condition of fencing of the fields.
Besides the protection of vulnerable crops the reduction of wild boar populations by means of hunting is crucial for damage prevention. Hunting rates have to be increased and hunting effort should focus on females of all age classes, but especially on juvenile females, which have shown to be highly reproductive and substantially contribute to population growth. For this purpose, selective hunting techniques like hide hunting and stalk hunting should be prioritised and promoted.
The highly reproductive wild boar possesses the ability to recover from population losses in a very short time. Hence, both effective hunting management and field protection will remain the most important tools for damage control. Further research is required to investigate and compare different wild boar management systems including also damage prevention under an economic perspective. Stakeholders like farmers, hunters, and authorities must be involved.
The omnivore wild boar is enabled to adapt to various environments. Wild boar populations are expected to increase further and to spread into areas not yet populated. In Switzerland, the spread into the central parts of the country will also be supported by additional wildlife crossings that are in construction or in process of planning which will pose a challenge for wildlife management in these regions
Population genomics of domestic and wild yeasts
Full text linkThe natural genetics of an organism is determined by the distribution of sequences of its genome. Here we present one- to four-fold, with some deeper, coverage of the genome sequences of over seventy isolates of the domesticated baker's yeast, _Saccharomyces cerevisiae_, and its closest relative, the wild _S. paradoxus_, which has never been associated with human activity. These were collected from numerous geographic locations and sources (including wild, clinical, baking, wine, laboratory and food spoilage). These sequences provide an unprecedented view of the population structure, natural (and artificial) selection and genome evolution in these species. Variation in gene content, SNPs, indels, copy numbers and transposable elements provide insights into the evolution of different lineages. Phenotypic variation broadly correlates with global genome-wide phylogenetic relationships however there is no correlation with source. _S. paradoxus_ populations are well delineated along geographic boundaries while the variation among worldwide _S. cerevisiae_ isolates show less differentiation and is comparable to a single _S. paradoxus_ population. Rather than one or two domestication events leading to the extant baker's yeasts, the population structure of _S. cerevisiae_ shows a few well defined geographically isolated lineages and many different mosaics of these lineages, supporting the notion that human influence provided the opportunity for outbreeding and production of new combinations of pre-existing variation
Wild Sorghums—Their Potential Use in Crop Improvement
Full text linkWild relatives of crops, sorghum being no exception, continue to
play a key role in the development of high performing cultivars.
Among the 22 species comprising this highly variable genus, only
one, Sorghum bicolor, is commercially cultivated for food, feed and
bioenergy production. The wild sorghums thus offer opportunities
for further genetic enhancement of this crop. Profi table utilization of
wild species however demands an inter-disciplinary, multi-pronged
approach to increase the probability of achieving the desired genetic
improvement. To this end, this chapter presents a review of the current
knowledge on (1) biosystematic aspects such as botany, taxonomy
and classifi cation, (2) domestication and evolution, including centers
of diversity, genetic diversity, chromosome homologies and species/
phylogenetic relationships, (3) genetic resources, genepools and
conservation perspectives including collections and preservation of
germplasm, (4) utilization aspects including the specifi c potential of
the wild species in crop improvement with reference to insect and
disease resistance, yield, grain quality, ecological adaptation, allopatric
resistance, and (5) strategies to maximize utilization of wild germplasm
resources including direct hybridization, reproductive barriers and their
circumvention, chromosome and physiological manipulation, the gaps
between hybridization and utilization and molecular interventions.
Recent advancements in biotechnology, in particular, are expected
to increase the effi ciency and range of use of these wild sorghum
species
POLIMI-ITW-S: A large-scale dataset for human activity recognition in the wild
Full text linkHuman activity recognition is attracting increasing research attention. Many activity recognition datasets have been created to support the development and evaluation of new algorithms. Given the lack of datasets collected in real environments (In The Wild) to support human activity recognition in public spaces, we introduce a large-scale video dataset for activity recognition In The Wild: POLIMI-ITW-S. The fully labeled dataset consists of 22,161 RGB video clips (about 46 h) including 37 activity classes performed by 50 K+ subjects in real shopping malls. We evaluated the state-of-the-art models on this dataset and get relatively low accuracy. We release the dataset including the annotations composed by person tracking bounding boxes, 2-D skeleton, and activity labels for research use at: https://airlab.deib.polimi.it/polimi-itw-s-a-shopping-mall-dataset-in-the-wild
Population Genetic Approaches to Speciation of Wild Tomatoes with Special Reference to Solanum habrochaites and S. arcanum
Full text linkThis thesis entails the results of three research projects. These have focused on the influence of diversity, demography and structure in the divergence (i.e. the speciation process) of four wild tomato species. In the first project, using coalescent simulations, we studied the impact of three different sampling schemes on patterns of neutral diversity in structured populations. Specifically, we evaluated two summary statistics based on the site frequency spectrum (Tajima’s D and Fu and Li’s D) as a function of migration rate, demographic history of the entire metapopulation and the sampling scheme. Using simulations, we demonstrate strong effects of the sampling scheme on Tajima’s D and Fu and Li’s D statistics, particularly under specieswide expansions. Under such scenarios, the effects of spatial sampling may persist up to very high levels of gene flow (Nm > 25). This suggests that validating the assumption of panmixia is crucial if robust demographic inferences are to be made from local or pooled samples.
For the second project, we investigated how selection acts in four species of wild tomatoes (S. habrochaites, S. arcanum, S. peruvianum, and S. chilense) using sequence data from eight housekeeping genes. Our analysis quantified the number of adaptive and deleterious mutations, and the distribution of fitness effects of new mutations (its mean and variance) taking into account the demography of the species. We found no evidence for adaptive mutations but very strong purifying selection in coding regions of the four species. More interestingly, the four species exhibit different strength of purifying selection in non-coding regions (introns). Taking into account the results from the first project, we also highlighted the utility of analyzing pooled samples and local samples from a metapopulation in order to measure selection and the distribution of fitness effects.
Finally, the third project deals with the estimation of nucleotide diversity and population structure in S. habrochaites and S. arcanum. We also compared these results to those of S. peruvianum and S. chilense. We found that S. arcanum and S. habrochaites present lower diversity levels than S. peruvianum and S. chilense. Our neutrality tests have not revealed any particular pattern, leading us to conclude that the loci sequenced for the present study have not evolved under strong positive selection, although they show a distinctive pattern of purifying selection (second project). We also tested the demography of all four species and found a strong expansion after a bottleneck in the recent past for S. peruvianum and a similar statistically significant pattern for S. arcanum, even though the signal seemed weaker in this case. Additionally, we found moderate levels of population sub-structure in these species, similar to previous results found in S. peruvianum and S. chilense. Still, regardless of the levels of population structure, we found at least two (Rupe and San Juan from S. arcanum) populations collected in the field that could actually be considered as a single deme. We also expanded these population structure analyses to gain insight into the phylogenetic relations between the four species in order to contribute to the taxonomical treatment of the Solanum section Lycopersicon from a population genetics perspective. Thus, we found a clear differentiation between S. arcanum and S. peruvianum based on all polymorphic sites
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