Marine ecosystems can be exposed to natural and anthropogenic disturbances that can lead to ecological failures. Marine reserves have been lately suggested to protect marine populations and communities that have been affected by habitat destruction and harvest. This research evaluates the potential role of two marine reserves established in Oregon in 1967 (Whale Cove) and 1993 (Gregory Point). The red sea urchin (Strongylocentrotus franciscanus) was selected as indicator of population recovery since it is the only species that is commercially harvested. Changes in density, biomass, average size, size structure, growth and mortality rates were evaluated through time to assess population recovery. These parameters were also compared between reserves and adjacent exploited areas to evaluate the effect of exploitation. Results from Whale Cove (old reserve) indicate that the population in this area is fully recovered. On the contrary, the population in Gregory Point (new reserve) showed signs of recovery after six years of being protected. The importance of red urchins as source populations to provide larvae to adjacent areas was explored by the analysis of drifter's trajectories. Both reserves might be connected in a network where larvae produced in Whale Cove will provide recruits to Gregory Point and adjacent exploited areas, as well as populations in northern California. Gregory Point releases larvae that become recruits for Whale Cove only when spawning takes place in winter, otherwise larvae travel to central California. No clear trends were found in growth and mortality rates between reserves and non-reserves; differences were more related with food availability, competitors, and age specific mortality. We applied qualitative simulations to characterize and differentiate the community network inside reserves and exploited areas. Results suggest that communities from a particular site can be represented by a set of alternative models with consistent species interactions. Differences in predator-prey interactions as well as non-predatory relationships (interference competition, mutualism, amensalism) were found among sites. Each set of models represents a hypothesis of community organization that agreed with natural history information. Alternative models suggest that kelp forest communities are dynamic and can shift from one network configuration to another providing a buffer against a variable environment. / Graduation date: 2002

Virtually all diurnal birds have tetrachomatic vision based on four different colour receptors. As a result, birds are potentially able to perceive their environment in twice as many colours as humans and four times as many colours compared to most other mammals, which are dichromatic. In addition to the spectrum visible to humans, birds are able to detect ultraviolet (UV) light. Signals with a UV component have been shown to be important to birds both in foraging and colour signalling. Because of the superior colour discrimination of the avian eye, UV sensitivity, but especially owing to its tetrachromacy, we cannot know what birds look like to those that matter, i.e. other birds. In my thesis I describe a new molecular method with which it is possible to identify the vision system of birds only using a small amount of DNA, without the need to keep or sacrifice the animal. It thereby facilitates large screenings, including rare and endangered species. The method has been used to increase the number of species with identified vision system type from 19 to 66. I show that raptors and songbirds have different vision systems, giving songbirds the possibility of a secret channel for colour signalling, and that male songbirds in coniferous forest take advantage of this to be significantly more cryptic to raptors than to females songbirds. I show that gulls have gained a vision system enabling them to detect the UV signals of fish when the fish swim close to the surface. Even though we tend to be rather self-satisfied with the quality of our colour vision, we are colour-blind when compared to birds. My work shows that human colour vision is inadequate for judging animal coloration, and that there is much more going on in bird colour signalling than meets our eye.

A low content of organic matter, which is largely refractory in nature, is characteristic of most sediments, meaning that aquatic deposit-feeders live on a very poor food source. The food is derived mainly from sedimenting phytodetritus, and in temperate waters like the Baltic Sea, from seasonal phytoplankton blooms. Deposit-feeders are either bulk-feeders, or selective feeders, which preferentially ingest the more organic-rich particles in the sediment, including phytodetritus, microbes and meiofauna. The soft-bottom benthos of the Baltic Sea has low species biodiversity and is dominated by a few macrobenthic species, among which the most numerous are the two deposit-feeding amphipods Monoporeia affinis and Pontoporeia femorata, and the bivalve Macoma balthica. This thesis is based on laboratory experiments on the feeding of these three species, and on the priapulid Halicryptus spinulosus. Feeding by benthic animals is often difficult to observe, but can be effectively studied by the use of tracers. Here we used the radioactive isotope 14C to label food items and to trace the organic matter uptake in the animals, while the stable isotopes 13C and 15N were used to follow feeding on aged organic matter in the sediment. The abundance of M. balthica and the amphipods tends to be negatively correlated, i.e., fewer bivalves are found at sites with dense populations of amphipods, with the known explanation that newly settled M. balthica spat are killed by the amphipods. Whether the postlarvae are just accidentally killed, or also ingested after being killed was tested by labelling the postlarvae with 14C and Rhodamine B. Both tracer techniques gave similar evidence for predation on and ingestion of postlarval bivalves. We calculated that this predation was likely to supply less than one percent of the daily carbon requirement for M. affinis, but might nevertheless be an important factor limiting recruitment of M. balthica. The two amphipods M. affinis and P. femorata are partly vertically segregated in the sediment, but whether they also feed at different depths was unknown. By adding fresh 14C-labelled algae either on the sediment surface or mixed into the sediment, we were able to distinguish surface from subsurface feeding. We found M. affinis and P. femorata to be surface and subsurface deposit-feeders, respectively. Whether the amphipods also feed on old organic matter, was studied by adding fresh 14C-labelled algae on the sediment surface, and using aged, one-year-old 13C- and 15N-labelled sediment as deep sediment. Ingestion of old organic matter, traced by the stable isotopes, differed between the two species, with a higher uptake for P. femorata, suggesting that P. femorata utilises the older, deeper-buried organic matter to a greater extent. Feeding studies with juveniles of both M. affinis and P. femorata had not been done previously. In an experiment with the same procedure and treatments as for the adults, juveniles of both amphipod species were found to have similar feeding strategies. They fed on both fresh and old sediment, with no partitioning of food resources, making them likely to be competitors for the same food resource. Oxygen deficiency has become more wide-spread in the Baltic Sea proper in the last half-century, and upwards of 70 000km2 are now devoid of macrofauna, even though part of that area does not have oxygen concentrations low enough to directly kill the macrofauna. We made week-long experiments on the rate of feeding on 14C-labelled diatoms spread on the sediment surface in different oxygen concentrations for both the amphipod species, M. balthica and H. spinulosus. The amphipods were the most sensitive to oxygen deficiency and showed reduced feeding and lower survival at low oxygen concentrations. M. balthica showed reduced feeding at the lowest oxygen concentration, but no mortality increase. The survival of H. spinulosus was unaffected, but it did not feed, showing that it is not a surface deposit-feeder. We conclude that low oxygen concentrations that are not directly lethal, but reduce food intake, may lead to starvation and death in the longer term.

The social organization of animal societies has important implications for several fields of biology, from managing wild populations to developing new ecological and evolutionary theory. Although much attention has been given to the formation and maintenance of societies of group living individuals, less is known about how societies of solitary individuals have been shaped and maintained. Traditionally, the evolution of social organizations in the mammalian order Carnivora has been regarded as a directional selection process from a solitary ancestry into progressively more advanced forms of sociality. In this thesis, I tested this model against an alternative model, assuming radiation from a socially flexible ancestry. I further explored sociality, resource use and dispersal of a solitary carnivore, the wolverine (Gulo gulo), in the light of these two evolutionary models. Phylogenetic reconstruction generally supported that carnivore social organizations evolved through directional selection from a solitary ancestor. However, results from captive wolverine females indicated that they might have rudimentary social tendencies, which rather support that sociality in carnivores radiated from a socially flexible ancestry. Wild wolverines in northwestern Brooks Range, Alaska, adhered to the commonly found ecological niche as a largely ungulate dependent generalist carnivore. Lack of sexual asymmetry in dispersal tendencies indicated that resource competition among wolverine females probably was high. I suggest that wolverines have latent abilities to aggregate, but that their phylogenetic legacy in terms of morphology has constrained them into an ecological niche where resource abundance and distribution generally inhibit aggregations. Due to contradictory results, I suggest further research to test evolutionary theory regarding carnivore social evolution, and particularly to explore new avenues into social evolution that better explain intra-specific variation in sociality, as well as formation and maintenance of solitary social systems.

Natural stress and disturbances are important factors affecting the structure and function of ecosystems. However the magnitude of stress has escalated due to anthropogenic activities. Environmental monitoring and toxicity assessments try to protect ecosystems from unwanted human alterations. The aim of this Doctoral thesis was to increase the understanding of the complex effects that environmental stress has on individuals and invertebrate populations. The low saline environment in the Baltic Sea is perceived as stressful for most organisms living there. In Paper I, it was found that Baltic blue mussels living in the less saline northern Baltic Proper (~5 psu) had lower basal metabolism and were more susceptible to toxic exposure than the mussels in the south (~7 psu). There was no genetic differentiation between the mussels from the northern and southern areas while there were genetic differences between mussels from sites within the respective areas (Paper III), indicating that there is not a simple relationship between the health of the mussels and genetic diversity in the microsatellite loci studied. In Paper IV it was found that the heat tolerance of the intertidal dogwhelk Nucella lapillus is oxygen dependent. Increased oxygen levels resulted in higher survival rate. Protein expression profiles also became more similar to those of the controls, compared to the whelks exposed to high temperature and normal oxygen levels. In Paper V and VI it was found that exposure to a single toxicant for more than one generation decreased the genetic diversity in exposed copepod populations even though abundances remained unaltered. In Paper VI, exposure to naturally contaminated sediments, which contained of a mixture of toxicants, did not decrease genetic diversity. However the genetic divergence (FST) within the treatments was very high, probably due to small effective population sizes in the replicates. Likewise in Paper III, the very low blue mussel abundance in the north together with the stressful environment suggests a small effective population in the northern Baltic Proper. In conclusion, my studies show that, measuring effects on several levels, including both functional and structural endpoints will both increase the sensitivity of the tests and increase their ecological relevance.

In this thesis we have studied speciation in three butterfly genera Polygonia (Nymphalidae, Nymphalini), Pararge (Nymphalidae, Satyrinae) and Celastrina (Lycaenidae: Polyommatinae). In the first paper a dated phylogeny, based on molecular data, of Polygonia was constructed. We found strong conflict between the nDNA and mtDNA datasets. Possibly this can be explained by ancestral and recent hybridizations between contemporary taxa. The results point to the importance in using different markers when we try to resolve evolution of taxa. In the second paper a sister group comparison was made in order to discover whether host plant range has had an effect on species diversity in Polygonia. Our result indicated higher diversification rates in clades which included species with larvae feeding on different, or additional, plants compared to the ”urticalean rosids” specialists. In the third paper our focus was on the colonization abilities in polyphagous butterflies. The haplotype structures of the mtDNA cytochromeoxidase I (COI) within the Nearctic species of Celastrina as well as within P. c-album and P. faunus were analysed in a network. We found little variation in Celastrina and P. c-album. This results imply that the genera have expanded recently and rapidly. There are indications of differentiation in COI in Celastrina and, possibly, host plant use is involved. However, in P. faunus we found structure among the haplotypes. We believe that several different haplotypes of this species have been preserved during glaciations in the Nearctic. In the fourth paper the evolution of the grassfeeding Pararge was analysed. The phylogeny was based on the mtDNA COI and the nDNA wingless (wgl) and times of divergences were calculated. We found a deep divergence between the European and Moroccan populations of P. aegeria which indicates the importance of the Mediterranean as a barrier for gene flow.

The climate change is expected to affect especially alpine areas negatively, replacing the alpine flora with subalpine forest. The understanding of how vegetation influences total organic carbon (TOC) in soil, streams and lakes in alpine and subalpine areas will lead to a better understanding of the effects of climate change, and will also increase the knowledge of the ecotone as a whole. In this study plant-soil relations were examined in a subalpine and an alpine catchment in the north of Sweden, by comparing dissolved organic carbon (DOC) concentrations, 13C-DOC, 13 compared with lake and stream water DOC, as well as sediment OC from the recipient lakes in the catchments.  The results show that subalpine forests at lower altitudes, have higher DOC concentrations, higher C:N ratios, and more depleted Particulate OM in water and inlets, show that allochthonous carbon influences water properties in both catchments, as does primary production by benthic and pelagic algae, separating shallow and deep sediment Differences between the catchments are explained with the higher primary production of organic material and root exudations from trees in the subalpine forested catchment effecting the whole catchment dynamics. C-SOM and the carbon to nitrogen (C:N) ratios. The terrestrial bulk chemical properties of DOC were alsoδ13C signals in soil, and soil-solution compared to alpine areas. δ13C signals from Dissolved OM andδ13C signals.

Energiflöden mellan terrestra och akvatiska ekosystem har uppmärksammats mycket den senaste tiden. I den här studien undersöker jag betydelsen av ett terrestert djur, älgen (Alces alces), som dör i vattendrag och avger näring till vattnet. Genom litteraturstudier och teoretiska beräkningar uppskattade jag hur vanligt det är att älgar dör i vattendrag och om dessa älgar har någon inverkan på vattendragets totala näringsbudget. Jag fann att drunkning hos älgar tas upp som en parameter för naturliga dödsorsaker i flera artiklar från USA, Canada och Polen. Orsakerna till att älgar drunknar, trots att de är duktiga simmare, kan vara t.ex. att stranden är för brant, att de tvingas ner i vattnet av rovdjur, att skadeskjutna älgar söker sig till vatten på grund av törstkänningar i samband med blodförlust eller att de går igenom svaga isar. Utifrån teoretiska beräkningar fann jag även att en älg som dött i ett vattendrag bidrar till mycket liten del av den totala näringsbudgeten. Min hypotes är att det endast blir en lokal påverkan nedströms djuret. Hur denna påverkan ser ut och om den kommer primärproducenter och fiskar tillgodo är mycket komplext och undersöks inte i denna studie.

Statistical modelling is often used to relate the presence or abundance of species to environmental predictors, thereby providing a basis for predictive mapping of species or biodiversity. The variables included must thus be relevant and reflect actual changes in the environment. Therefore, the quantification of species–environment relationships is an important aspect of predictive modelling. This thesis examines how phytobenthic species or communities in the Baltic Sea relate to environmental gradients, and if different aspects of phytobenthic species distribution in the Baltic Sea could be explained by spatial or temporal variation in environmental factors. Predictive distribution modelling usually focuses on how environmental variables control the distribution of species or communities. Thus the relative weight of the predictor variables on different scales is of importance. In this thesis, I show that the relative importance of environmental variables depends both on geographic scale and location, and that it also differs between species or species groups. There are no simple explanations to the temporal variability in species occurrence. I here show that the temporal changes in species distribution within the phytobentic zone varies in a spatial context. I also try to find temporal and spatio-temporal patterns in species distribution that could be related to changes in climate or anthropogenic disturbance. However, the findings in this thesis suggest that single factor explanations are insufficient for explaining large-scale changes in species distribution. A greater understanding of the relationship between species and their environment will lead to the development of more sensitive models of species distributions. The predictions can be used to visualise spatial changes in the distribution of plant and animal communities over time. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.

The impacts of two strains of the dinoflagellate Alexandrium tamarense, differing in lytic activity, on the abundance and the composition of microbial communities (<150 μm) were studied in North Sea water during spring with Phaeocystis globosa as a dominant species. Cell-free suspensions (supernatant) of exponentially growing lytic and non-lytic Alexandrium culture were added at different concentrations to natural microbial communities under nutrient rich conditions. The non-lytic strain had a positive impact on diatoms whereas the lytic strain suppressed phytoplankton growth in comparison to the control. P. globosa, present as single cells in the initial community, increased in abundance and formed colonies in all treatments. However, total abundance and number of colonies was low with lytic Alexandriumadditions, whereas shape of the colonies, but not abundance of cells, was affected by non-lytic Alexandrium additions. During the 4-day experiment, bacterial abundance was constantly higher with high lytic additions (highest concentration equivalent to 1000 cells ml−1) whereas nanoflagellate abundance in the same treatments was found to be lower at the end of the experiment. Initial bacterial community composition differed significantly among lytic Alexandrium, non-lyticAlexandrium and North Sea water. However, neither bacterial activity nor composition was significantly affected by the supernatants after 96 h. Our results indicated that Alexandrium allelochemicals do not inhibit growth and production of bacteria in seawater collected during spring in the North Sea. / Allelopathy among phytoplankton - a structuring force among phytoplankton