Effective population size (Ne) is a fundamental concept within biology and can be defined as the size of an ideal Wright-Fisher population in which the rate of genetic drift is the same as in the observed population. Natural populations are not ideal so that Ne is often < Nc. A low Ne can lead to inbreeding depression and less adaptability in a population, thus it is essential to know Ne for threatened populations. Ne can be estimated using genetic or demographic data. In this study four different genetic estimators (LDNE, ONeSAMP, MLNE and CoNe) and one demographic estimator were compared using data from a natural house sparrow metapopulation. How Ne related to Nc was also examined. All four genetic estimators seemed to be upwardly biased, however, LDNE often produced estimates in the expected range (Ne<N) and thus appeared to be less biased. To understand how characteristics of natural populations may affect the rate of genetic drift it is important to examine what influence the Ne/Nc-ratio. Thus, I investigated whether population characteristics such as population size, sex ratio, immigration rate, variance in population size and population growth rate explained the variation in the Ne/N ratio for the different genetic estimators. A general result was that the immigration rate had a positive effect on the Ne/Nc-ratio. The apparent upward bias of genetic Ne estimates and the positive effect of immigration rate on Ne/Nc-ratio suggest that gene flow between subpopulations within the study metapopulation was of significant importance for the rate of genetic drift. Genetic estimators of Ne seem like promising tools. However, if no knowledge of the ecology of the population in question exists, Ne should be interpreted cautiously. When assumptions underlying estimators are violated this can lead to erroneous conclusions about genetic processes in the population. 

Question: How does nutrient addition and seeding affect revegetation of seed plants, and are the effects differing among the stages of the regeneration pathway? Location: Two roads restored in 2002, located in Hjerkinn firing range, in lower alpine zone of Dovrefjell, Norway.Methods: Abundance of species and functional types (dwarf shrubs, forbs and graminoids) in four stages of the regeneration pathway (seed rain, seed bank, field seedlings and established vegetation) was recorded seven years after road reconstruction in treatment plots (with nutrient addition, nutrient + seed addition and no treatment). Results: The graminoid Deschampsia cespitosa dominated the vegetation and seed rain in fertilized plots, while the seeded Festuca rubra still dominated the seeded + fertilized plots. The germinable seed bank was lowest in the seeded + fertilized treatment, while the control plots had the highest number of seedlings germinating in the field. Dwarf shrubs had a high germination rate in the field, despite low rates in the seed rain and seed bank. The highest rate of dwarf shrub seedlings was in control plots, while the frequency of dwarf shrubs in the established vegetation increased with nutrient addition. Forbs had species specific responses.Conclusions: Both treatments that included nutrients were dominated by graminoids, with a higher vegetation cover and frequency of dwarf shrubs than the control plots. While graminoids are the most efficient seed producers, they are less able to germinate and survive as seedlings. Dwarf shrubs accounted for a high proportion of germinating seedlings in the field, but the low frequencies of dwarf shrubs in the established control plot vegetation suggest either low seedling survival or an ongoing successional change. It remains to be revealed if the high recruitment of dwarf shrubs in the control plots will speed up the establishment of the typical dwarf shrub cover similar to the surrounding vegetation and hereby indicate that unassisted recovery is the fastest way to restore alpine dwarf shrub heath.

Sik (Coregonus lavaretus) dominerte i littorale- og littorale habitater. Røyr hadde størst utbredelse i profundale habitater. Artene viste betydelig næringsoverlapp.

The ongoing global warming is especially pronounced in the arctic, and it is therefore important to investigate the effect of these changes on arctic ecosystems. In this study the Snow bunting (Plectrophenax nivalis) breeding in Spitsbergen, Svalbard was used as a model species to investigate how the climatic variations are affecting avian reproduction. Both big scale climatic parameters and local weather variables were included in an analysis of how these factors affected snow bunting breeding success. It turned out that both big scale and local variables were important. Locale temperature and wind was important for time off breeding. Temperature, precipitation, winter North Atlantic Oscillation (NAOw) and winter Arctic Oscillation (AOw) were important for number of fledged chicks, and wind and air pressure were important for growth rate.

Dispersal propensity can vary considerably between individuals in a population. Understanding which individuals disperse- and under what circumstances these individuals disperse is valuable for conservation. Factors influencing juvenile movement and natal dispersal were studied in individually marked house sparrows, Passer domesticus, in an archipelago off the coast of Helgeland, northern Norway. Sex, clutch size, body size and body mass did not significantly explain variation in movement. Movement rate was however negatively related to hatch date on one of the islands. Moreover, there was a decrease in movement rate with increasing patch isolation and hostility of the matrix habitat. This study suggests that habitat configuration is an important factor determining movement of juvenile house sparrows, and that the environment experienced early in life may be related to movement propensity. I strongly recommend incorporating landscape features in further analyses of movement and dispersal rate.

Hydropeaking corresponds to the management of hydropower resources where electricity is produced in accordance with prices and demand. Although fully justified economically, hydropeaking may have adverse consequences for the aquatic ecosystem. Due to frequent and rapid fluctuations in water discharge hydropeaking could generate negative effects on the ecosystem downstream the outlet of the hydropower station. Frequent fluctuations in water discharge, altered temperature regime, substrate composition and vegetation cover can result in reduced macroinvertebrate density and variety downstream the outlet of hydropower stations. Furthermore, macroinvertebrates inhabiting the shallow zone could be exposed to stranding as a consequence of frequent dewatering of the river-margin.In order to provide environmental guidelines for the hydropower industry, it is essential to understand how changes brought upon hydropeaked rivers affect the aquatic ecosystem.We studied the effect of hydropeaking on the total macroinvertebrate density and on the density, diversity and species richness of the orders Ephemeroptera and Plecoptera in two hydropeaked rivers, the Bævra River and the Lundesokna River, in central Norway. Findings from the given study demonstrated negative effects on the macroinvertebrates, likely caused by hydropeaking. The results showed a lowered total density and a lowered density, diversity and species richness of Ephemeroptera and Plecoptera in the locations exposed to frequent dewatering. In the permanently water covered location, however, there was less indication of a hydropeaking effect. These findings suggest that hydropeaking prevent establishment of normal benthic macroinvertebrate communities in the exposed shallow location, while the macroinvertebrate fauna in the permanently water covered location are less affected.

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Bilberry (Vaccinium myrtillus) is native to Europe and North America and constitutes an important nutritional resource for both humans and animals. Over the years, a series of chemical analyses have revealed several health-beneficial compounds in bilberry, and with the current demand of the berries mainly covered by Sweden and Eastern Europe, there has become an increasing desire to cultivate bilberry in Norway. In order for such cultivation to be successful an increased knowledge about bilberry is seen as essential and thus several studies have investigated the chemical composition of the berry. However, the underlying genetic diversity and the variation between populations in biochemical compounds remain to be thoroughly investigated. Therefore, the aim of present study was to investigate the differences in biochemical composition between populations of bilberry distributed on a latitudinal gradient, and estimate the level of genetic variation within and among the populations. This in order to examine whether biochemical composition was reflected by observed levels of genetic variation.Bilberries from four Norwegian populations at three regions differing in latitude were analysed for content of total phenolics (TPH), total anthocyanins (ACY) and antioxidant activity (FRAP). Furthermore, metabolic profiling was performed by gas chromatography-mass spectrometry (GC-MS) to reveal biochemical differences between the populations in content of sugars, acids and some simple phenolics. Multivariate statistics were performed and revealed a clustering of samples from the two locations in Mid-Norway, and a clustering of the northern with the southern population. In addition, there were found significant differences in some of the compounds between the populations.Genetic analyses using four microsatellites were carried out to examine whether metabolic differences between populations were reflected by genetic differentiation. Despite the significant differences between populations in the concentrations of some metabolites no significant genetic differentiation was found. Thus, it seems that the variation in biochemical compounds discovered among populations could be environmentally induced differences on a similar genetic background. However, due to the limited number of working microsatellites and the fact that these molecular markers are neutral, there is still a possibility that the genetic differences causing compound concentrations to differ could be so minor as to remain undetected. Hence, further studies utilizing more microsatellite markers or new state-of-the-art molecular techniques are needed to determine whether this result holds and is valid also for genetic variation in coding parts of the genome.

In Norway today no commercial exploitation of the wild growing Norwegian bilberry (Vaccinium myrtillus) exists. The market in other regions of Europe, North- and South-America is based on the utilization of cultivated Vaccinium species. V.myrtillus shows generally a higher content of biochemical compounds with health-beneficial properties. As a consequence of an increasing demand for healthier food, the Nordic Bilberry project started in 2008 with the major goal to find superior clones adapted for different regions with effective production of phytochemicals. In addition, a 4-years Norwegian Bilberry project aiming at cultivation and yield potential aspects, was launched the same year (NFR project no. 184797). The presented master projected was affiliated to this project focusing on phytochemical and genetic diversity in Bymarka. It is known that life history traits of a plant species influence the clonal diversity and structure within populations. In this thesis different phytochemical methods were used for detection of total phenolics, anthocyanins and antioxidants in berry and plant material from 4 different areas in the geographic restricted area Bymarka, were a total of 80 individuals were collected. Average values detected for total phenols were 490 mg/100 g, 155 mg/ 100 g for anthocyanins and 4 mmol/ 100 g for antioxidants. The results showed little variation among clones in the restricted area. 16 primer pairs for 16 microsatellite loci were tested but only 4 (NA741, NA961, CA421 and CA483) turned out to be of good quality. These microsatellite loci were used to estimate genetic variability within and between populations. Little genetic variation was detected between the different plots, and populations had similar levels of within-population genetic variation. The highest diversity both genetic and phytochemically was found in plot D with berries without any wax layer. This plot was also more genetically different from the other populations than the berries in the same location/area/plot with a wax layer, though no significant differences was found in FST, Heterozygosity observed, Heterozygosity expected or allelic richness (P<0.05). The result from this thesis could be used further for improvement of breeding strategies and selection of cultivars with high phenolic contents for production of quality food.

African savannah elephants play a vital role in the Serengeti ecosystem with the opportunity to alter the entire ecosystem by its sheer number. Management of these animals are therefore of high importance, but little genetic research has been done thus far in the ecosystem. Their recent traumatic history of poaching serves as a template for intriguing evolutionary theories and further understanding of elephant behavior. In this study it was investigated on the genetic structure and spatial differentiation of the elephants in Serengeti using a mitochondrial DNA (mtDNA) marker. A widespread sample size of 55 elephants were collected in three zones of the Serengeti National Park (West, North and Seronera) and analyzed for genetic diversity. The results gave the impression of a slightly outbreeding population with no ongoing subdivision (FST = -0.04864, p = 0.92082). A total of 7 haplotypes were obtained with one clearly being dominant (78.2 %). All collected haplotypes were compared to earlier studies using the same mitochondrial marker and having a wider perspective, with samples ranging across the sub-Saharan Africa. Results show that there is a possibility that the elephants now inhabiting the Serengeti are primary descendants of Northern populations coming from Kenya and Uganda, with additional individuals giving the impression that the Serengeti elephants are a mixture of individuals with historical connections from all over sub-Saharan Africa.