• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 3
  • 2
  • 1
  • Tagged with
  • 13
  • 8
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Host habitat influences on oviposition by Parasetigena silvestris (R-D), a tachinid parasite of the gypsy moth.

Harrington, Eugene Arthur 01 January 1977 (has links) (PDF)
No description available.
2

Facial expressions and other behavioral responses to pleasant and unpleasant tastes in cats  (Felis silvestris catus)

Hanson, Michaela January 2015 (has links)
The behavior and facial expressions performed by cats have been reported to be visibly affected by the perceived taste quality of a food item. The goal of the present study was to assess how cats react to pleasant and unpleasant tastes. The facial and behavioral reactions of 13 cats to different concentrations of L-Proline and quinine monohydrochloride as well as mixtures with different concentrations of the two substances were assessed using a two-bottle preference test. The cats were videotaped during the tests and the frequency and duration of 50 different behaviors was analyzed in Noldus the Observer XT. The cats responded to tastes regarded as pleasant by having their eyes less than 50 % open for significantly longer periods of time compared to a water control. Tongue protrusions were also observed significantly more frequently when the cats sampled from a solution with a preferred taste compared to a water control. When encountering solutions of quinine monohydrochloride or mixtures containing quinine monohydrochloride the cats were observed to perform tongue protrusion gapes much more frequently compared to a water or L-Proline control. Even though the cats did not significantly differ in the number of times they licked at spouts containing the 50 mM L-Proline and 500 mM quinine monohydrochloride mixture compared to a 50 mM L-Proline, no masking effect could be confirmed as there was no increase in the acceptance of the mixture was observed. The present study suggests that the knowledge about behavioral responses to pleasant or unpleasant taste can be utilized in future studies on how cats perceive different tastes.
3

Vyhodnocení přirozené a umělé obnovy borovice lesní na majetku Městských lesů Hradec Králové

Ježek, Petr January 2011 (has links)
No description available.
4

Introgression and the current status of the Scottish wildcat (Felis silvestris silvestris)

Kilshaw, Kerry A. January 2015 (has links)
Baseline data on a species' distribution and abundance are essential for developing practical conservation management plans. Such data are difficult to obtain for many low density cryptic carnivores. The Scottish wildcat, Felis silvestris silvestris, is no exception with &LT;400 individuals thought to remain. Its conservation has been further complicated by extensive hybridisation and introgression with the domestic cat (F.s.catus). Hybridisation has also resulted in difficulties in discriminating between wildcats, wildcat x domestic hybrids (hybrids) and tabby coloured feral domestic cats. This has inhibited survey efforts, leading to a lack of general ecological information. Using the most recent identification tools available, extensive surveys using various methods including camera trapping were carried out across Northern Scotland in order to examine the current status of the Scottish wildcat. Current distribution indicates a more restricted range than recent studies. Wildcats are at risk of hybridisation from feral domestic cats and in particular, hybrids, throughout their current probable range. The distribution of hybrids overlaps with both feral domestic cats and wildcats, pointing to a significant threat from hybrids acting as a bridge between wildcats and feral cats. Mean density estimates of 3.5 (SD=0.7) wildcats/100 km<sup>2</sup> were comparable with those from other studies in Scotland using different survey methods. Total population size estimates ranged between 115-314 individuals depending on local densities and home range size. Population viability analysis (PVA) indicated the current population is not viable unless management actions are undertaken in the near future (Mean time to extinction = 48.2 years (SD = 9.39), probability of extinction=1, SE = 0), and that reducing mortality rates and/or supplementing populations from captive bred cats are likely to be necessary to achieve viability. Based on these data, the Scottish wildcat may be more endangered than many other species classified as Endangered and the current status of the Scottish wildcat should be reviewed.
5

Rozšíření kočky divoké (Felis silvestris) v ČR / geomatické modelování a ekologický přístup / Distribution of wildcat (Felis silvestris) in Czech Republic / geomatic modelling and ecological approach

Pospíšková, Jana January 2015 (has links)
Population of the European wildcat (Felis silvestris) are slowly recovering after a severe decline in the 18th century. The wildcat was a rare species already on the beginning of 19th century on the territory of Czech Republic. During the 20th century the species was considered to be extinct and the scarce records to be individuals dispersed from Carpathian or West-European population. Furthermore there was lack of evidence to this observations. With the expansion of photo monitoring methods, there comes pictures of wildcats from the Beskid Mountains, Bohemian Forest, The upper Palatine Forest and Doupov mountains. After more than 60 years there is finely a proof for the presence of wildcats in Czech Republic. To understand its space requirements and dispersion context, and to know if there is a place for wildcats to live in Czech Republic, we made a habitat model in ArcGIS. This rule-based model works with attributes like land cover type, duration of snow cover, aspect and the vertical heterogeneity of terrain. The model was applied also for Slovakia, because the evaluation data only comes from Slovakia. We found out that the occurence of wildcats in the model territory relate to broad-leaf forests, duration of snow cover (>20cm) not exceeding 50 days and the southern exposure. In Czech Republic there is...
6

Význam mykorhizní symbiózy v invazivnosti borovice vejmutovky / Significance of mycorrhizal symbiosis in invasiveness of Pinus strobus

Antl, Tomáš January 2014 (has links)
6 Abstract This study aimed to compare the mycorrhizal fungal communities inhabiting the roots of invasive Pinus strobus L. and native Pinus sylvestris L. We also compared carbon allocation into ectomycorrhizal fungal (EcMf) and other structures of the two pine species. The aim was to assess the influence of mycorrhiza on the invasive potential of P. strobus in the protected areas of National Park Bohemian Switzerland. The two field experiments were conducted on three locations of each species. We estimated the EcM extramatrical mycelium (EMM) production by measuring the ergosterol content in sterile sand filled mesh-bags. Next measured variables were: biomass of ectomycorrhizal and saprotrophic sporocarps, fine roots biomass and leaf litter biomass to compare the one season production of each measured variables. The results revealed a major difference in EcM sporocarps production, whereas on the P. sylvestris sites was the production 100% higher. Same results came from the fine roots measurements: P. sylvestris had a higher fine roots production, which may be also related with the production of EMM, which was about 60% higher as well. The EcMf species richness on the P. strobus root-tips was as high as the native pine, but the species composition was different. The P. strobus prefers EcMf species with...
7

Non-Linear Density Dependence in a Stochastic Wild Turkey Harvest Model

McGhee, Jay D. 23 February 2006 (has links)
Current eastern wild turkey (<I>Meleagris gallopavo silvestris</I>) harvest models assume density-independent population dynamics despite indications that populations are subject to a form of density dependence. I suggest that both density-dependent and independent factors operate simultaneously on wild turkey populations, where the relative strength of each is governed by population density. I attempt to estimate the form of the density dependence relationship in wild turkey population growth using the theta-Ricker model. Density-independent relationships are explored between production and rainfall and temperature correlates for possible inclusion in the harvest model. Density-dependent and independent effects are then combined in the model to compare multiple harvest strategies. To estimate a functional relationship between population growth and density, I fit the theta-Ricker model to harvest index time-series from 11 state wildlife agencies. To model density-independent effects on population growth, I explored the ability of rainfall, temperature, and mast during the nesting and brooding season to predict observed production indices for 7 states. I then built a harvest model incorporating estimates to determine their influence on the mean and variability of the fall and spring harvest. Estimated density-dependent growth rates produced a left-skewed yield curve maximized at ~40% of carrying capacity, with large residuals. Density-independent models of production varied widely and were characterized by high model uncertainty. Results indicate a non-linear density dependence effect strongest at low population densities. High residuals from the model fit indicate that extrinsic factors will overshadow density-dependent factors at most population densities. However, environmental models were weak, requiring more data with higher precision. This indicates that density-independence can be correctly and more easily modeled as random error. The constructed model uses both density dependence and density-independent stochastic error as a tool to explore harvest strategies for biologists. The inclusion of weak density dependence changes expected harvest rates little from density-independent models. However, it does lower the probability of overharvest at low densities. Alternatives to proportional harvesting are explored to reduce the uncertainty in annual harvests. / Ph. D.
8

Des concepts et méthodes associés à la co-circulation des virus dans les populations naturelles d’hôtes à la nécessité d’interdisciplinarité : l’exemple du chat et de ses virus / From concepts and methods associated with viruses’ co-circulation in natural populations to the need for interdisciplinarity : the example of the cat and its viruses

Hellard, Éléonore 06 April 2012 (has links)
De nombreux parasites circulent dans les populations naturelles. Au sein d’un hôte, souvent pluri-infecté, ils peuvent interagir, augmentant ou réduisant le risque d’infection et les symptômes d’autres pathogènes. L’étude de ces interactions commence seulement dans les populations naturelles. Les enjeux sont cruciaux : détecter les interactions d’intérêt, estimer la probabilité de coinfection, comprendre la cocirculation des parasites. La détection des interactions sur le terrain est compliquée par la nature des données (e.g., présence-absence) et les facteurs confondants créant des associations statistiques (fausses interactions). Ce travail visait à mener une réflexion transversale sur ces interactions et le multiparasitisme, avec des applications à des données sérologiques pour 4 virus félins suivis dans des populations rurales de chats domestiques. De nouvelles méthodes de modélisation dynamique et statistique ont été développées pour prendre en compte les facteurs générant de fausses interactions (effet cumulatif de l’âge, facteurs de risque communs) et évaluer le biais des méthodes classiques. Des synergies entre 3 couples de virus félins ont été révélées. On a aussi identifié des caractéristiques comportementales et physiologiques (modes de vie, niveau de testostérone), qui, en modulant l’exposition et la sensibilité aux pathogènes, génèrent une forte hétérogénéité entre les hôtes. Enfin, une vision intégrative des systèmes hôte-parasites est indispensable pour appréhender la complexité des communautés et évaluer l’impact de la multitude d’hôtes, de parasites et d’interactions sur la coévolution, la conservation des espèces et la gestion des maladies infectieuses / Numerous parasites circulate within natural host populations. Within a host, often pluri-infected, parasites can interact, increasing or decreasing the infection risk and/or symptoms’ severity of other pathogens. Studies of such interactions only start in natural populations. Their stakes are high: detecting interactions of interest, estimating coinfection probabilities and understanding the cocirculation of parasites. The detection of interactions in the field is however complicated by the nature of data (often presence-absence) and the existence of confounding factors that can create statistical associations (false interactions). This work aimed at having a cross-cutting reflection on those interactions and on multiparasitism, with applications on a rich dataset of four feline viruses followed in rural populations of domestic cats. New dynamical and statistical modeling methods were developed to take into account factors generating false interactions (cumulative effect of age, shared risk factors) and evaluate the biases of classical methods. Synergies between three pairs of feline viruses were revealed. In addition, we identified behavioral and physiological factors (e.g., way of life, testosterone levels) that, by modulating exposition and/or susceptibility to pathogens, generate strong heterogeneity between hosts. Finally, a more integrative approach to host-parasites systems is proposed. It now appears necessary if one wants to deal with communities’ complexity and further evaluate the impact of multiple hosts, multiple parasites and their interactions on their coevolution, species conservation and infectious diseases management
9

Camera Trapping Large Mammals In Yenice Forest Habitats: A Feasibility Study For Camera Trapping Large Mammals In Yenice Forests, Turkey

Can, Ozgun Emre 01 September 2008 (has links) (PDF)
Widely applicable, quantitative field methods are needed to gather wildlife data for conservation and management initiatives in Turkey. In order to evaluate the use of camera traps in forest habitats of Turkey, we conducted a 5 phase camera trap survey by using 16 passive infrared-triggered cameras with a total sampling effort of 1200 camera trap days in Yaylacik Research Forest, a 50 km2 forest patch of Yenice Forest in Karab&uuml / k during January-May 2006. The camera trap survey confirmed the presence of grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), red fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) in the study area. The camera trap survey also revealed the presence of jackal (Canis aureus) and brown hare (Lepus europaeus), whose presence were not known by people living and working in the area. Contrary to the local belief, neither camera trapping survey nor ground survey confirmed the presence of lynx (Lynx lynx) in Yaylacik Research Forest. The wolf was observed to be crepuscular and the wildcat showed a diurnal activity pattern. Wildcat seemed to avoid other carnivores spatially and temporally. Simulation studies suggested that camera trap surveys should last 14 days for wolf, 13 days for wildcat, 10 days for pine marten, and 11 days for roe deer, while it is advisable to conduct longer surveys, probably 15-20 days, for wild boar, red fox and brown bears. The estimated population size for wildcat was 9 (SE=2.28227) with 95% confidence interval of 9 to 25 in the study area. A minimum of 6 brown bears were present in the study area. Our study indicated that the local knowledge about the presence of wildlife should be considered by researchers, but it cannot replace scientific surveys conducted by field biologists. This study was the first attempt to assess the presence, relative abundance, activity patterns and diversity of multiple mammal species by the use of camera trapping methodology in Turkey. The results suggest that camera trap surveys have the potential for gathering wildlife data at larger scales in Turkey, where information gap on large mammals is an obstacle for effective management and conservation of mammals.
10

Origin of the Egyptian Domestic Cat

Johansson, Carolin January 2012 (has links)
This study presents mitochondrial genome sequences from 22 Egyptian house cats with the aim of resolving the uncertain origin of the contemporary world-wide population of Domestic cats. Together with data from earlier studies it has been possible to confirm some of the previously suggested haplotype identifications and phylogeny of the Domestic cat lineage. Moreover, by applying a molecular clock, it is proposed that the Domestic cat lineage has experienced several expansions representing domestication and/or breeding in pre-historical and historical times, seemingly in concordance with theories of a domestication origin in the Neolithic Middle East and in Pharaonic Egypt. In addition, the present study also demonstrates the possibility of retrieving long polynucleotide sequences from hair shafts and a time-efficient way to amplify a complete feline mitochondrial genome.

Page generated in 0.0614 seconds