<p>Since the start of the industrialisation, the deposition of nitrogen and sulphur and the atmospheric concentrations of greenhouse gases have increased. The main objectives of this study were to find how these changes in climate and deposition can change the vegetation of mire ecosystems and the growth of <i>Sphagnum</i>species. Two main approaches were applied: re-investigated of two mires previously investigated 40-50 years ago and experiment manipulations. </p><p>The plant species diversity had decreased on one of the two re-investigated mires (Skattlösbergs Stormosse; central Sweden), but the total number of species was unchanged on the other (Åkhultmyren; southern Sweden). On Skattlösbergs Stormosse, an acidification was found in the high pH areas, coinciding with reduction in rich fen species. At Åkhultmyren, there was a similar reduction in pH, but the changes in the plant composition also indicated increased nutrient levels and a drier mire surface. Therwere large changes in species composition on Åkhultmyren. For instance <i>Scheuchzeria palustris</i> had disappeared from the investigated area. Further, the cover of Scots pine (<i>Pinusylvestris</i>) had increased, which can be explained by a changed ground-water table regime. Monitoring of pines growing on a bog over a ten-year period showed that pines growing higher above the ground-war table had higher survival than lower-growing pines.</p><p>Experimental addition of nitrogen during 3-4 years reduced <i>Sphagnum </i>growth in bogs and poor fens repressenting a wide range of ambient nitrogen deposition. A changed interspecific competitive relation was found between <i>S. lindberg</i>and <i>S. balticum</i> when increasing nitrogen influx, but the competitive relations between two hummock-growing species pairs did not change in a three-year nitrogen fertilization study. Sulphur additiodid not affect the production or length increment in <i>S. balticum</i>. An increased temperature reduced <i>Sphagnum </i>growth, but there were no indications of altered competitive relationshipbetween hummock and hollow inhabiting <i>Sphagnum </i>species in a four-year experiment.</p>

<p>A number of environmental pollutants have been shown to mimick the action of the female sex hormone estrogen and are, therefore, suspected to be responsible for reproductive abnormalities seen in wildlife. Test systems which can be used in hazard and risk assessment of chemicals with estrogenic effects are consequently needed. In this thesis, I propose the avian egg as an <i>in vivo</i> test system for estrogenic compounds. I conclude that malformation of the left testis and the Müllerian ducts (MDs: embryonic oviducts) in avian embryos can be used as endpoints to examine estrogenic activity of chemicals. MD malformation is more easily determined and thereby faster to use as an endpoint than histologically observed feminization of the testis. The usefulness of MD/oviduct malformations as biomarkers for estrogenic effects in wild birds should be considered. </p><p>The environmental pollutants bisphenol A (BPA) and <i>o,p´</i>-DDT induced similar effects as the synthetic estrogens, ethynylestradiol and diethylstilbestrol. BPA caused MD malformations in quail embryos and ovotestis formation in chicken embryos. <i>o,p´</i>-DDT induced MD malformations in both quail and chicken embryos and ovotestis in chicken embryos. The flame retardant, tetrabromobisphenol A did not induce estrogen-like effects in quail or chicken embryos, but showed a relatively high embryolethality. </p><p>Embryonic exposure to estrogen caused persisting malformations of the oviduct, as well as a changed distribution pattern of the enzyme carbonic anhydrase in the shell gland of adult females. Considering the crucial role of carbonic anhydrase in shell formation, such changes could result in decreased shell quality. I propose that eggshell thinning in avian wildlife could reflect a functional malformation in the shell gland that is induced by xeno-estrogens during embryonic development, rather than being caused by exposure of the adult bird to environmental pollutants. This hypothesis opens new possibilities for studying the mechanisms behind contaminant-induced eggshell thinning in birds.</p>

<p>In the fifteen-spined stickleback, <i>Spinachia spinachia</i>, males provide females with direct benefits by fanning, cleaning and guarding the offspring. Males announce their parental skills through intense body shakes during courtship. Females preferred to mate with more intensely shaking males. As a result, females got better fathers for their offspring, as such males achieved a higher hatching success. Not only did male behavioural cues attract females, but males also used their nests as extrabodily ornaments. The nest is held together with shiny secretional threads consisting of a glycoprotein. Females chose to spawn in nests with more secretional threads. A likely reason for this is that the threads are metabolically costly for the male to produce and the amount of secretion indicates a male's nutritional status, which is of great importance as parental duties are energetically costly. Moreover, females preferred nests built high up in the vegetation, as such nests were safer from egg predators. Competition with other males for females favoured males building higher nests than did their neighbours, probably because females preferred high nests. Male-male interactions, such as sneaking and egg stealing, caused decreased paternity among males in nature as assessed by a microsatellite analysis. Males adjusted their paternal effort according to their previous investment in the brood, but not according to paternity. Thus, female choice is based on multiple cues and results in better paternal care. Males invest in courtship, male-male competition, nest construction and paternal care, the outcome determining their success in mate attraction.</p>

<p>This thesis focuses on a black-tailed godwit (<i>Limosa limosa</i>) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small size of the population makes it more prone to extinction due to chance events, than a larger population.</p><p>The godwits showed microhabitat preferences when choosing nest sites. Godwit nests had higher vegetation over the nest cup, lower surrounding (1-3 m) vegetation and different plant species composition, as compared to random sites. Breeding near conspecifics or other wader species, especially lapwings (<i>Vanellus vanellus</i>) and further away from potential predator perches were the most important factors in decreasing nest predation. A comparison between different shore meadows along the east coast of the island revealed that large, open areas suffered less from nest predation. Thus, shore meadows suitable for breeding godwits should be large and without trees or other predator perches and have a grazing regime that favours variation in vegetation height.</p><p>Over 80% of previously ringed adults returned each year, but very few birds ringed as chicks were recovered. Hatching success was 55-60% for all observed nests. To predict the future of the current population, demographic data were used in an ecological risk analysis. The simulations showed that the Gotlandic population will not survive the coming 40 years without immigration.</p><p>Black-tailed godwits are divided into three subspecies. Genetic analyses (mtDNA) revealed that all subspecies had unique haplotypes and there was a clear geographic structure among subspecies. Within the <i>limosa</i> subspecies, godwits on Gotland and Öland showed a high proportion of rare haplotypes, but no genetic variation was found in Dutch birds. These results imply that black-tailed godwits on Gotland and Öland have high conservation value.</p>

<p>Stress can affect several behavioural patterns, such as food intake and the general activity level of an animal. The central monoamine neurotransmitters serotonin, dopamine, and norepinephrine are important in the mediation of both behavioural and neuroendocrine stress effects. This thesis describes studies of two salmonid fish model systems: Fish that become socially dominant or subordinate when reared in pairs, and rainbow trout (<i>Oncorhynchus mykiss</i>) genetically selected for high (HR) and low (LR) stress responsiveness, in terms of stress induced cortisol release. Socially subordinate individuals are often subject to chronic stress, and it was found that plasma cortisol and brain monoaminergic activity rapidly increased in subordinate fish during the initial 24 h period following fights for social dominance in pairs of rainbow trout. In pairs of Arctic char (<i>Salvelinus alpinus</i>), subordinate individuals were characterised by an inhibition of food intake and aggression, and low spontaneous locomotion. Appetite inhibition in subordinate fish was reversed by subsequent rearing in isolation, and this effect was probably related to a concomitant decrease in brain serotonergic activity. Furthermore, differential stress responsiveness in HR and LR rainbow trout was associated with differences in behaviour, as well as changes in brain monoaminergic activity. HR fish displayed higher locomotor activity when challenged by a conspecific intruder. This response was probably related to a larger stress induced activation of brain dopaminergic systems in these fish. Finally it was shown that the steroid 'stress-hormone' cortisol has dose- and context-dependent behavioural effects in fish, as has been described in mammals. Specifically, short- term cortisol treatment elevated the behavioural response to a territorial intruder, while long-term treatment, like chronic stress, had the opposite effect, inhibiting locomotor activity and aggression. It is concluded that the signalling systems involved in behavioural and neuroendocrine control during stress display extensive similarities between teleost fishes and mammals.</p>

This thesis focuses on the evolutionary interactions between birds and a parasite, the mosquito-borne Sindbis virus (Togaviridae, Alphavirus). In conclusion, the results show that the Sindbis virus is widespread among birds, and that the fitness of infected hosts may be reduced by the virus. Furthermore, viruclearance ability was revealed by male plumage traits, and viraemia was related to hormonal- and social status. The distribution of Sindbis virus infections among passerine birds was examined in five areas in Sweden. Almost all species tested were infected, and three species of thrushes weridentified as the main hosts. In a series of experimental infections, greenfinches (Carduelis chloris) kept in aviaries were used ahosts. First, the behavioural consequences of an infection were investigated. During the infection, birds tended to reduce thespontaneous locomotion activity, and when escaping from a simulated predator attack, infected birds had reduced take-off spee Furthermore, when comparing virus clearance rate between male greenfinches, I found that males with large yellow tail ornaments hafaster virus clearance rates as compared to those with smaller ornaments. Thus, male virus clearance ability was honestly revealed by the size of an ornament. Moreover, males with experimentally elevated testosterone levels experienced a delayed, but not increased viraemia as compared to controls. When the relationship between male social ranand viraemia was examined, I found no evidence that high-ranked males suffered reduced rank during the infection. Nevertheless, viraemipatterns of males were related to their social rank, so that low-ranked birds had a delayed viraemia as compared to high-ranked birds.

Since the start of the industrialisation, the deposition of nitrogen and sulphur and the atmospheric concentrations of greenhouse gases have increased. The main objectives of this study were to find how these changes in climate and deposition can change the vegetation of mire ecosystems and the growth of Sphagnumspecies. Two main approaches were applied: re-investigated of two mires previously investigated 40-50 years ago and experiment manipulations. The plant species diversity had decreased on one of the two re-investigated mires (Skattlösbergs Stormosse; central Sweden), but the total number of species was unchanged on the other (Åkhultmyren; southern Sweden). On Skattlösbergs Stormosse, an acidification was found in the high pH areas, coinciding with reduction in rich fen species. At Åkhultmyren, there was a similar reduction in pH, but the changes in the plant composition also indicated increased nutrient levels and a drier mire surface. Therwere large changes in species composition on Åkhultmyren. For instance Scheuchzeria palustris had disappeared from the investigated area. Further, the cover of Scots pine (Pinusylvestris) had increased, which can be explained by a changed ground-water table regime. Monitoring of pines growing on a bog over a ten-year period showed that pines growing higher above the ground-war table had higher survival than lower-growing pines. Experimental addition of nitrogen during 3-4 years reduced Sphagnum growth in bogs and poor fens repressenting a wide range of ambient nitrogen deposition. A changed interspecific competitive relation was found between S. lindbergand S. balticum when increasing nitrogen influx, but the competitive relations between two hummock-growing species pairs did not change in a three-year nitrogen fertilization study. Sulphur additiodid not affect the production or length increment in S. balticum. An increased temperature reduced Sphagnum growth, but there were no indications of altered competitive relationshipbetween hummock and hollow inhabiting Sphagnum species in a four-year experiment.

A number of environmental pollutants have been shown to mimick the action of the female sex hormone estrogen and are, therefore, suspected to be responsible for reproductive abnormalities seen in wildlife. Test systems which can be used in hazard and risk assessment of chemicals with estrogenic effects are consequently needed. In this thesis, I propose the avian egg as an in vivo test system for estrogenic compounds. I conclude that malformation of the left testis and the Müllerian ducts (MDs: embryonic oviducts) in avian embryos can be used as endpoints to examine estrogenic activity of chemicals. MD malformation is more easily determined and thereby faster to use as an endpoint than histologically observed feminization of the testis. The usefulness of MD/oviduct malformations as biomarkers for estrogenic effects in wild birds should be considered. The environmental pollutants bisphenol A (BPA) and o,p´-DDT induced similar effects as the synthetic estrogens, ethynylestradiol and diethylstilbestrol. BPA caused MD malformations in quail embryos and ovotestis formation in chicken embryos. o,p´-DDT induced MD malformations in both quail and chicken embryos and ovotestis in chicken embryos. The flame retardant, tetrabromobisphenol A did not induce estrogen-like effects in quail or chicken embryos, but showed a relatively high embryolethality. Embryonic exposure to estrogen caused persisting malformations of the oviduct, as well as a changed distribution pattern of the enzyme carbonic anhydrase in the shell gland of adult females. Considering the crucial role of carbonic anhydrase in shell formation, such changes could result in decreased shell quality. I propose that eggshell thinning in avian wildlife could reflect a functional malformation in the shell gland that is induced by xeno-estrogens during embryonic development, rather than being caused by exposure of the adult bird to environmental pollutants. This hypothesis opens new possibilities for studying the mechanisms behind contaminant-induced eggshell thinning in birds.

In the fifteen-spined stickleback, Spinachia spinachia, males provide females with direct benefits by fanning, cleaning and guarding the offspring. Males announce their parental skills through intense body shakes during courtship. Females preferred to mate with more intensely shaking males. As a result, females got better fathers for their offspring, as such males achieved a higher hatching success. Not only did male behavioural cues attract females, but males also used their nests as extrabodily ornaments. The nest is held together with shiny secretional threads consisting of a glycoprotein. Females chose to spawn in nests with more secretional threads. A likely reason for this is that the threads are metabolically costly for the male to produce and the amount of secretion indicates a male's nutritional status, which is of great importance as parental duties are energetically costly. Moreover, females preferred nests built high up in the vegetation, as such nests were safer from egg predators. Competition with other males for females favoured males building higher nests than did their neighbours, probably because females preferred high nests. Male-male interactions, such as sneaking and egg stealing, caused decreased paternity among males in nature as assessed by a microsatellite analysis. Males adjusted their paternal effort according to their previous investment in the brood, but not according to paternity. Thus, female choice is based on multiple cues and results in better paternal care. Males invest in courtship, male-male competition, nest construction and paternal care, the outcome determining their success in mate attraction.

This thesis focuses on a black-tailed godwit (Limosa limosa) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small size of the population makes it more prone to extinction due to chance events, than a larger population. The godwits showed microhabitat preferences when choosing nest sites. Godwit nests had higher vegetation over the nest cup, lower surrounding (1-3 m) vegetation and different plant species composition, as compared to random sites. Breeding near conspecifics or other wader species, especially lapwings (Vanellus vanellus) and further away from potential predator perches were the most important factors in decreasing nest predation. A comparison between different shore meadows along the east coast of the island revealed that large, open areas suffered less from nest predation. Thus, shore meadows suitable for breeding godwits should be large and without trees or other predator perches and have a grazing regime that favours variation in vegetation height. Over 80% of previously ringed adults returned each year, but very few birds ringed as chicks were recovered. Hatching success was 55-60% for all observed nests. To predict the future of the current population, demographic data were used in an ecological risk analysis. The simulations showed that the Gotlandic population will not survive the coming 40 years without immigration. Black-tailed godwits are divided into three subspecies. Genetic analyses (mtDNA) revealed that all subspecies had unique haplotypes and there was a clear geographic structure among subspecies. Within the limosa subspecies, godwits on Gotland and Öland showed a high proportion of rare haplotypes, but no genetic variation was found in Dutch birds. These results imply that black-tailed godwits on Gotland and Öland have high conservation value.