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Livestock Populations (livestock + population)
Selected AbstractsEffects of human,livestock,wildlife interactions on habitat in an eastern Kenya rangelandAFRICAN JOURNAL OF ECOLOGY, Issue 4 2009John Otuoma Abstract Human,livestock,wildlife interactions have increased in Kenyan rangelands in recent years, but few attempts have been made to evaluate their impact on the rangeland habitat. This study identified drivers of increased human,livestock,wildlife interactions in the Meru Conservation Area between 1980 and 2000 and their effects on the vegetation community structure. The drivers were habitat fragmentation, decline in pastoral grazing range, loss of wildlife dispersal areas and increase in livestock population density. Agricultural encroachment increased by over 76% in the western zone adjoining Nyambene ranges and the southern Tharaka area, substantially reducing the pastoral grazing range and wildlife dispersal areas. Livestock population increased by 41%, subjecting areas left for pastoral grazing in the northern dispersal area to prolonged heavy grazing that gave woody plant species a competitive edge over herbaceous life-forms. Consequently, open wooded grassland, which was the dominant vegetation community in 1980, decreased by c. 40% as bushland vegetation increased by 42%. A substantial proportion of agro pastoralists were encountered around Kinna and Rapsu, areas that were predominantly occupied by pastoralists three decades ago, indicating a possible shift in land use in order to spread risks associated with habitat alterations. Résumé Les interactions hommes-bétail-faune sauvage ont augmenté dans les pâturages kényans ces dernières années, mais il y a eu peu de tentatives pour évaluer leur impact sur cet habitat. Cette étude identifie quelles ont été les raisons sous-jacentes de ces interactions dans l'Aire de Conservation de Meru entre 1980 et 2000, et leurs effets sur la structure de la communauté végétale. Les raisons étaient la fragmentation de l'habitat, le déclin de la surface libre pour le pâturage pastoral, la perte d'aire de dispersion pour la faune sauvage et l'augmentation de la densité de population du bétail. L'envahissement agricole a augmenté de plus de 76% dans la zone ouest touchant les fermes de Nyambene et l'aire sud de Tharaka, réduisant substantiellement l'étendue du pâturage pastoral et les aires de dispersion de la faune sauvage. La population du bétail a augmenté de 41%, soumettant les étendues laissées au pâturage pastoral dans la région de dispersion nord à un pâturage intensif prolongé qui a donné aux espèces végétales ligneuses un avantage sur les formes herbeuses. Par conséquent, la prairie arborée ouverte, qui était la communauté végétale dominante dans les années 1980 a diminué de près de 40% alors que la végétation de broussailles a augmenté de 42%. Une proportion substantielle d'agropastoralistes se rencontraient autour de Kinlla et de Rapsu, des zones qui étaient principalement occupées par des pasteurs il y a trois décennies, ce qui indique une évolution possible de l'utilisation des sols afin de disperser les risques liés à l'altération des habitats. [source] Development of novel SNP system for individual and pedigree control in a Japanese Black cattle population using whole-genome genotyping assayANIMAL SCIENCE JOURNAL, Issue 4 2010Kazuhiro HARA ABSTRACT Individual identification and parentage analysis using DNA markers are essential for assuring food identity and managing livestock population. The objective of this study was to develop a single nucleotide polymorphism (SNP) panel system for individual effective identification and parentage testing in a Japanese Black cattle population using BovineSNP50 BeadChip. On the basis of SNP frequencies, 60 unlinked informative SNPs were finally selected as candidate markers. The allelic frequencies for each SNP were estimated using additional individuals by PCR-RFLP (restriction fragment length polymorphism). A total of 87 SNP markers added in conjunction with previously developed 27 SNPs were evaluated to assess the utility of the test. The estimated identity power was 2.01 × 10,34. Parentage exclusion probabilities, when both suspected parents' genotypes were known and when only one suspected parent was genotyped, were estimated as 0.99999997 and 0.99998010, respectively. This developed SNP panel was quite powerful and could successfully exclude false sires with a probability of >0.9999 even if the dam's genotype information was not obtained. The SNP system would contribute to management of the beef industry in Japan. [source] Long-term land-cover changes in the Belgian Ardennes (1775,1929): model-based reconstruction vs. historical mapsGLOBAL CHANGE BIOLOGY, Issue 7 2002C. C. Petit Abstract Understanding long-term human-environment interactions requires historical reconstruction of past land-cover changes. The objective of this study is to reconstruct past land-use and land-cover changes in a rural municipality of the Belgian Ardennes over the last 250 years. Two approaches were compared. The first approach produced backward projections based on a mechanistic model which computes the demand for different land uses under the assumption of an equilibrium between the production and consumption of resources. The second approach involved using a series of historical maps to extract directly land-use areas. A stochastic Markov chain model was also used to project backward missing land-cover data in the time series. The consistency between the results obtained with the different approaches suggests that land-use area can be successfully reconstructed on the basis of the mechanistic model, under conditions of a subsistence farming system and a closed economy. Land-use/cover changes in the Belgian Ardennes from 1775 to 1929 were more driven by the interventionist measures of the Belgian government and by technological progress than by the ,pressure' of the growing population and livestock. Thanks to agricultural intensification, a decrease in land under human use was supporting increasing human and livestock populations from 1846 to 1880. Reforestation has accelerated since the mid-19th century. This case study illustrates the highly dynamic and non-linear character of land-use change trajectories over long time periods and their strong interactions with the history of societies. [source] Epistatic kinship a new measure of genetic diversity for short-term phylogenetic structures , theoretical investigationsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2006C. Flury Summary The epistatic kinship describes the probability that chromosomal segments of length x in Morgan are identical by descent. It is an extension from the single locus consideration of the kinship coefficient to chromosomal segments. The parameter reflects the number of meioses separating individuals or populations. Hence it is suggested as a measure to quantify the genetic distance of subpopulations that have been separated only few generations ago. Algorithms for the epistatic kinship and the extension of the rules to set up the rectangular relationship matrix are presented. The properties of the epistatic kinship based on pedigree information were investigated theoretically. Pedigree data are often missing for small livestock populations. Therefore, an approach to estimate epistatic kinship based on molecular marker data are suggested. For the epistatic kinship based on marker information haplotypes are relevant. An easy and fast method that derives haplotypes and the respective frequencies without pedigree information was derived based on sampled full-sib pairs. Different parameters of the sampling scheme were tested in a simulation study. The power of the method decreases with increasing segment length and with increasing number of segments genotyped. Further, it is shown that the efficiency of the approach is influenced by the number of animals genotyped and the polymorphism of the markers. It is discussed that the suggested method has a considerable potential to allow a phylogenetic differentiation between close populations, where small sample size can be balanced by the number, the length, and the degree of polymorphism of the chromosome segments considered. [source] Objectives, criteria and methods for using molecular genetic data in priority setting for conservation of animal genetic resourcesANIMAL GENETICS, Issue 2010P. J. Boettcher Summary The genetic diversity of the world's livestock populations is decreasing, both within and across breeds. A wide variety of factors has contributed to the loss, replacement or genetic dilution of many local breeds. Genetic variability within the more common commercial breeds has been greatly decreased by selectively intense breeding programmes. Conservation of livestock genetic variability is thus important, especially when considering possible future changes in production environments. The world has more than 7500 livestock breeds and conservation of all of them is not feasible. Therefore, prioritization is needed. The objective of this article is to review the state of the art in approaches for prioritization of breeds for conservation, particularly those approaches that consider molecular genetic information, and to identify any shortcomings that may restrict their application. The Weitzman method was among the first and most well-known approaches for utilization of molecular genetic information in conservation prioritization. This approach balances diversity and extinction probability to yield an objective measure of conservation potential. However, this approach was designed for decision making across species and measures diversity as distinctiveness. For livestock, prioritization will most commonly be performed among breeds within species, so alternatives that measure diversity as co-ancestry (i.e. also within-breed variability) have been proposed. Although these methods are technically sound, their application has generally been limited to research studies; most existing conservation programmes have effectively primarily based decisions on extinction risk. The development of user-friendly software incorporating these approaches may increase their rate of utilization. [source] The origin of selection signatures on bovine chromosome 6ANIMAL GENETICS, Issue 2 2008B. J. Hayes Summary The extent and pattern of linkage disequilibrium (LD) between closely spaced markers contain information about population history, including past population size and selection history. Selection signatures can be identified by comparing the LD surrounding a putative selected allele at a locus to the putative non-selected allele. In livestock populations, locations of selection signatures identified in this way should be correlated with QTL affecting production traits, as the populations have been under strong artificial selection for these traits. We used a dense SNP map of bovine chromosome 6 to characterize the pattern of LD on this chromosome in Norwegian Red cattle, a breed which has been strongly selected for milk production. The pattern of LD was generally consistent with strong selection in regions containing QTL affecting milk production traits, including a strong selection signature in a region containing a mutation known to affect milk production. The results demonstrate that in livestock populations, the origin of selection signatures will often be QTL for livestock production traits, and illustrate the value of selection signatures in uncovering new mutations with potential effects on quantitative traits. [source] Genetical genomics in livestock: potentials and pitfallsANIMAL GENETICS, Issue 2006C. Haley Summary Genetical genomics combines gene mapping and gene expression approaches to identify loci controlling gene expression (eQTLs) that may underlie functional trait variation. The combination of genomic tools has great potential to facilitate dissection of complex traits, but studies need careful design and interpretation. Here we explore both the potential and the pitfalls of this approach with illustrations from actual studies. There are now an appreciable number of studies in model species and even humans demonstrating the feasibility of genetical genomics. However, most studies are too limited in size and design to unlock the full potential of the approach. Limited statistical power of studies exacerbates the problem of detection of false-positive eQTL and some reported results should be interpreted with caution. As one approach to more successful implementation of genetical genomics, we propose to combine expression studies with fine mapping of functional trait loci. This synergistic approach facilitates the implementation of genetical genomics for species without inbred resources but is equally applicable to model species. These properties make it particularly suitable for livestock populations where many QTL are already in the public domain and potentially very large pedigreed populations can be accessed. [source] | ||||||||||