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2284 Uppsatser om Population size - Sida 1 av 153
Rådjur (Capreolus Capreolus) på Gotland : populationsutveckling och spridningsmönster
Gotland is an island in the Baltic Sea where man has introduced roe deer. The last successful reintroduction was in the 1980s and is the base of the viable roe deer population of today.The aim of this study was to estimate the roe deer population density in 2012 and the species population dynamic since the time when studies on the population started. The result indicates a Population size of 850 roe deer in 2012. There was no significant population dynamic, which may be due to insufficient data. The population occurs basically over the whole island but have not yet been established in all suitable areas.
Hassel (Corylus avellana) som indikator på markanvändningshistorik
Hazel (Corylus avellana L.) is a common feature of meadows and pastures where it can grow in large populations and become very old. Is it possible to use the size of hazel stools for age determination and is it possible to use the size distribution of a population to provide information about how the land has been used? Hazel populations on ground where the lake-water level had been lowered, has been studied to validate an already developed growth model of hazel clones. Different hazel populations, on wooded meadows affected by mowing or grazing or overgrown meadows, were studied to evaluate the method utilizing hazel as land use indicator. The growth model was used to compare the size distributions of hazel populations with historical periods, which has been important for changes in agriculture or demography.
Påverkas mosippa (Pulsatilla vernalis) negativt av igenväxning?
Pulsatilla vernalis is one of several endangered plant species that benefit from wildfires and small scale disturbance events that repel competing vegetation and create open patches in the vegetation cover. Previous studies argue that Pulsatilla vernalis is decreasing in numbers due to vegetation changes associated with the decrease in wildfires, forest grazing and changes in forest management. In this study, 17 populations of P. vernalis were inventoried in order to examine if soil and/or vegetation structures affect the population structure of P. vernalis (i.e.
Stjälkröksvamp (Tulostoma brumale) : stora eller små individer?
The spatial population structure of the saprotrophic basidiomycete Tulostoma brumale was investigated at a site in south eastern Sweden. Sporocarps were mapped and collected, and somatic incompatibility tests between mycelial cultures cultivated from the sporocarps were used to identify genets. Calculations of the size and numbers of genets and their distribution were performed. The spatial distribution of the tested sporocarps and the identified genets are presented graphically in a grid. The total number of identified genets within the investigated area (1210 m2) was 27 based on 48 tested sporocarps.
Hur livshistoriekaraktärer hos Europeisk abborre (Perca fluviatilis L.) påverkas av cykliska förändringar i populationsstrukturen
This report deals with life-history variation for Eurasian perch (Perca fluviatilis L.), with special emphasis on age and size at maturity in females, in perch populations that have changed in size distribution. The collection of fish samples was made with multimesh gill nets year 2011. The perch?s length, height, weight, status of gonads has been analyzed, and by observing the opercular bone the age has been determined. In two lakes close to Umeå in northern Sweden, Fisksjön and Ängersjön, the live-history traits of perch have been studied.
Grey-sided vole and bank vole abundance in old-growth forest patches of different size and connectivity
Vole populations in northern Scandinavia vary in cycles with peaks every third or fourth year as described by the National Environmental Monitoring Programme of small mammals (NEMP). Some vole species have declined in population numbers since the NEMP started in 1971, especially the grey-sided vole (Myodes rufocanus) which is nearly extinct in the forested region. Since small mammals are an important food source for several avian and mammalian predators, the decline in vole numbers is expected to have consequences for the whole food chain, especially if other vole species start to decline in numbers. This study tried to test the hypothesis that presence and abundance of M. rufocanus (a specialist species) and Myodes glareolus (a generalist species) can be predicted by patch size and connectivity of forest patches >60 years old with a minimum of 15% pine >100years old.
Influence of the habitat on the potential for cannibalism and population dynamics in stream-dwelling European grayling (Thymallus thymallus L.)
Cannibalism can have major influence on fish population dynamics. A prerequisite for cannibalism is that the cannibal and the potential victim meet, and besides density effects, the encounter rate between cannibals and their victims is therefore also largely dependent on habitat use and habitat heterogeneity. In this study I quantified and compared the potential for cannibalism in stream-dwelling European grayling populations in three rivers in Jämtland by means of habitat classifications. I also analyzed population dynamic consequences of varying the potential for cannibalism in terms of intensity, using a physiological structured population model. Findings based on habitat characteristics were that the potential for cannibalism is in general not favourable in these types of streams.
Latitudinal patterns in body size of Roesel?s bush cricketMetrioptera roeselii within and outside the continuous area of its distribution
Over time, species colonize new areas naturally or through humans. The colonizers areoften few and founded populations represent only a fraction of the genetic diversityexisting in the original population. If the established population becomes isolated afterthe colonization event genetic diversity will remain low and if the population, in addition,remains small in size for an extended period this will lead to increased inbreeding andpossibly inbreeding depression. Metrioptera roeselii is a common species with awidespread distribution in continental Europe. During the last century, it has expanded tothe Scandinavian Peninsula which is separated from continental Europe by the Baltic Sea.My aim was to test the hypothesis that individuals in isolated populations in Scandinaviaincluding Denmark and the Baltic Sea islands are smaller than individuals in thecontinuous part of its distribution due to low genetic diversity and lacking incoming geneflow.
En ?terinventering och analys av den svenska populationen av svart nervmossa (Campylopus atrovirens)
Bristly swan-neck moss (Campylopus atrovirens) is in Sweden a very rare moss that only grows on a few blocks and cliffs around Gothenburg. The species can globally only be found in areas with high precipitation. Rain fall in Gothenburg has increased with a stronger greenhouse effect. Air pollution in Gothenburg has also improved. Mosses generally benefit from these conditions and this papers hypothesis is that the population of the species has grown because of these more beneficial conditions.
Genomisk selektion inom köttraser
Genomic selection (GS) is used for selection of breeding animals of dairy cattle. GS is though not as extensively used within the beef industry. One reason for that is the low accuracy (rTI) of the breeding value that is of great importance for the final genetic gain. Causes to the low accuracy are high effective Population size, a small reference population and a genetically differentiated population. There is however a market for genomic selection with High Density (HD) tests for beef cattle.
Medierepresentationen av världens länder : Strukturer i fyra svenska nyhetstidningar
This essay casts light on the quantitative aspect of the media representation of foreign news. The purpose of the essay is not only to describe the media representation of the countries of the world, but also to explain the representation out of structures that are mirrored by the mass media. Four hypotheses are stated that are operationalized in the research. These are treating four different factors that are believed to affect the representation, economy, geographical distance, cultural distance and the size of the population. A fifth hypothesis is stating that economy is the most influential of the factors.
Populationsstruktur och genetisk analys av exteriöra egenskaper hos svensk ardenner :
The purposes of this study were to estimate genetic and phenotypic parameters for conformation traits in Swedish Ardenner, a heavy draught horse, and to investigate the inbreeding status of the population. Additionally, a breeding scheme proposal was created, based on the results achieved in the study.
The data studied were obtained from the Swedish Horse Board and from the Swedish Ardenner Association. The data included 1632 three-year-old horses, mainly mares, and 356 stallions, judged between 1986 and 2005 at conformation shows. The traits studied were type, head-neck-body, legs, walk and trot at hand, total score and height at withers.
Göteborgs pendlingsomland. En studie om hur restid och reseavstånd korrelerar med pendling och befolkninsförändring i Västra Götalands och Hallands Län
The daily travel, and especially travel between home and work i.e. commuting, is increasing every passing year. More than 90 000 people commute from their home municipality to work in Gothenburg. One of the aims of the regions of Västra Götaland and Halland is to interconnect municipalities and towns within the region, thereby creating growth, faster freight and passenger transports as well as a more attractive business climate. However, while the goal is to create growth, there are several municipalities in the study region with negative ongoing trends.
Barngruppens storlek i förskolan ? en kvalitetsfråga? : Sex pedagogers reflektioner
This research is about six pedagogue´s and their reflections about the size of the children´s group in the preschools. Then I will discuss the pedagogue?s recommendation on the significance of the size of a children´s group learning and development and it´s practical significance for the preschool function. The pedagogue?s statements will be discussed in relation to The Swedish National Agency for Education (TSNAE) guidelines on group size.The theoretical framework of this essay will take an overview of the social cultural perspective, the group size and its significance for both the children´s learning and development, for interaction and communication and TSNAE advice and guidelines.
Superstores Marknadsföringsstrategier
Background: The increasing number of actors on the market has led to a more intense competition among superstores. With this, marketing has gotten an even more essential meaning. The marketing activities superstores perform are adapted to the context in which the store is located. Purpose: The purpose of this thesis is to, from different theoretical dimensions, compare superstores? application of marketing strategies in Tokyo with the marketing strategies used by superstores in Stockholm.