Food of Canis mesomelas in South Africa

The black-backed jackal is probably the most important problem animal in the sheep-farming areas of South Africa and especially in the Transvaal. To detennine the extent of damage done by Canis mesomelas in such areas, a study was initiated to analyse the stomach contents of black-backed jackals collected in South Africa. In 1965 Grafton published a preliminary report on the food of the black-backed jackal in South Africa. Since then many additional stomachs have been collected. However, as the analysis of the stomach contents is time consuming, it is profitable to detennine whether increasing the sample size beyond a certain point can add to existing knowledge. This is the primary aim of the present report

Food of the silver fox Vulpes Chama

Zoologica Africana 2(2): 205-21

Leopard range size and conservation area size in the southern Kalahari

The range use patterns of adult leopards were used to examine the impact of environmental quality on conservation area size in the arid south-western portion of the Kgalagadi Transfrontier Park in southern Africa. The ranges of the leopards are the largest recorded in the world, with a mean size of 2104.4 km2 (SEM 995.95 km2) for males and 1258.5 km2 (SEM 541.50 km2) for females. Overlaps in range use within and between the sexes and the size of this conservation area make it possible to sustain a genetically viable population of leopards in this arid environment. CONSERVATION IMPLICATIONS: When establishing conservation areas that contain large carnivores in arid and semi-arid regions, prey abundance and range use should be considered for the area to be able to sustain viable populations of such carnivores. The results emphasise the importance of establishing large transfrontier conservation areas where individual conservation areas are too small to do so. This study is the first to do so for leopards in southern Africa.J. du P.B. (University of Pretoria) was the project leader, was responsible for the project design, did the field research, collected the satellite GPS location details, analysed and interpreted the results and wrote the manuscript, whilst M.D.B. (Halls Head) did the ArcView and GIS analyses.The capture and radio-collaring of the leopards in this study occurred under strict supervision of trained staff of the South African National Parks and followed the ethical code of that organisation and of the University of Pretoria. The South African Natural History Unit of Route 66 Films allowed the use of some satellite radio-collar data. Funding was received from the University of Pretoria and Shayamanzi Game (Pty) Ltd (http://www.leopard.tv/index.php). The then Warden E.A.N. Le Riche gave valuable field support and B. Bothma typed numerous drafts of the manuscript. We sincerely thank them all.http://www.koedoe.co.zaam201

The Conservation Costs of Game Ranching

The devolution of user rights of wildlife in southern Africa has led to a widespread land-use shift from livestock farming to game ranching. The economic advantages of game ranching over livestock farming are significant, but so too are the risks associated with breeding financially valuable game where free-ranging wildlife pose a credible threat. Here, we assessed whether the conservation potential of game ranching, and a decentralized approach to conservation more generally, may be undermined by an increase in human-wildlife conflict. We demonstrate that game rancher tolerance towards free-ranging wildlife has significantly decreased as the game ranching industry has evolved. Our findings reveal a conflict of interest between wealth and wildlife conservation resulting from local decision-making in the absence of adequate centralized governance and evidence-based best practice. As a fundamental pillar of devolution-based natural resource management, game ranching proves an important mechanism for economic growth, albeit at a significant cost to conservation

Shadow Enhancers Foster Robustness of Drosophila Gastrulation

SummaryCritical developmental control genes sometimes contain “shadow” enhancers that can be located in remote positions, including the introns of neighboring genes [1]. They nonetheless produce patterns of gene expression that are the same as or similar to those produced by more proximal primary enhancers. It was suggested that shadow enhancers help foster robustness in gene expression in response to environmental or genetic perturbations [2, 3]. We critically tested this hypothesis by employing a combination of bacterial artificial chromosome (BAC) recombineering and quantitative confocal imaging methods [2, 4]. Evidence is presented that the snail gene is regulated by a distal shadow enhancer located within a neighboring locus. Removal of the proximal primary enhancer does not significantly perturb snail function, including the repression of neurogenic genes and formation of the ventral furrow during gastrulation at normal temperatures. However, at elevated temperatures, there is sporadic loss of snail expression and coincident disruptions in gastrulation. Similar defects are observed at normal temperatures upon reductions in the levels of Dorsal, a key activator of snail expression (reviewed in [5]). These results suggest that shadow enhancers represent a novel mechanism of canalization whereby complex developmental processes “bring about one definite end-result regardless of minor variations in conditions” [6]

Ab Initio Molecular Dynamics on the Electronic Boltzmann Equilibrium Distribution

We prove that for a combined system of classical and quantum particles, it is possible to write a dynamics for the classical particles that incorporates in a natural way the Boltzmann equilibrium population for the quantum subsystem. In addition, these molecular dynamics do not need to assume that the electrons immediately follow the nuclear motion (in contrast to any adiabatic approach), and do not present problems in the presence of crossing points between different potential energy surfaces (conical intersections or spin-crossings). A practical application of this molecular dynamics to study the effect of temperature in molecular systems presenting (nearly) degenerate states - such as the avoided crossing in the ring-closure process of ozone - is presented.Comment: published in New J. Phy

Movement patterns and athletic performance of leopards in the Okavango Delta

Although leopards are the most widespread of all the big cats and are known for their adaptability, they are elusive and little is known in detail about their movement and hunting energetics. We used high-resolution GPS/IMU (inertial measurement unit) collars to record position, activity and the first high-speed movement data on four male leopards in the Okavango Delta, an area with high habitat diversity and habitat fragmentation. Leopards in this study were generally active and conducted more runs during the night, with peaks in activity and number of runs in the morning and evening twilight. Runs were generally short (less than 100 m) and relatively slow (maximum speed 5.3 m s−1, mean of individual medians) compared to other large predators. Average daily travel distance was 11 km and maximum daily travel distance was 29 km. No direct correlation was found between average daily temperature and travel distance or between season and travel distance. Total daily energy requirements based on locomotor cost and basal metabolic rate varied little between individuals and over time. This study provides novel insights into movement patterns and athletic performance of leopards through quantitative high-resolution measurement of the locomotor, energetic, spatial and temporal movement characteristics. The results are unbiased by methodological and observational limitations characteristic of previous studies and demonstrate the utility of applying new technologies to field studies of elusive nocturnal species

Quantum Transition State Theory for proton transfer reactions in enzymes

We consider the role of quantum effects in the transfer of hyrogen-like species in enzyme-catalysed reactions. This study is stimulated by claims that the observed magnitude and temperature dependence of kinetic isotope effects imply that quantum tunneling below the energy barrier associated with the transition state significantly enhances the reaction rate in many enzymes. We use a path integral approach which provides a general framework to understand tunneling in a quantum system which interacts with an environment at non-zero temperature. Here the quantum system is the active site of the enzyme and the environment is the surrounding protein and water. Tunneling well below the barrier only occurs for temperatures less than a temperature $T_0$ which is determined by the curvature of potential energy surface near the top of the barrier. We argue that for most enzymes this temperature is less than room temperature. For physically reasonable parameters quantum transition state theory gives a quantitative description of the temperature dependence and magnitude of kinetic isotope effects for two classes of enzymes which have been claimed to exhibit signatures of quantum tunneling. The only quantum effects are those associated with the transition state, both reflection at the barrier top and tunneling just below the barrier. We establish that the friction due to the environment is weak and only slightly modifies the reaction rate. Furthermore, at room temperature and for typical energy barriers environmental degrees of freedom with frequencies much less than 1000 cm$^{-1}$ do not have a significant effect on quantum corrections to the reaction rate.Comment: Aspects of the article are discussed at condensedconcepts.blogspot.co