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Global warming is changing the ecohydrology and carbon fluxes of northern peatlands. If the soil moisture level remains high enough, peatland carbon sequestration may increase under longer and warming growing seasons, enhancing the cooling climate impact of peatlands. However, in case the evaporation overcomes precipitation, peatlands will dry. This leads to increased carbon dioxide emissions and the weakening of the cooling climate effect of peatlands. In addition, peatland methane fluxes are regulated by temperature and moisture conditions. What remains unknown, is which changes will be the most prominent and to which direction the climate impact of peatlands will develop in the future. The purpose of this thesis is to gain a better understanding of the peatland climate responses by investigating the recent vegetation development of a subarctic aapa mire. In August 2020, four surface peat cores were collected from the margin of Lompolojänkkä fen in Finnish Lapland. Recent changes in plant communities and carbon accumulation rates were investigated. Pb-210 dating method was applied to establish the chronology. A shift from a Cyperaceae-dominated community into a Sphagnum-dominated community in the beginning of the 1960s was detected. The shift indicates drying habitat conditions. Recent drying has been reported from several other northern peatlands. On the other hand, a similar expansion of Sphagna has been interpreted to be caused not only by hydrological changes but also directly by increasing temperatures, which cannot be ruled out in Lompolojänkkä either. Carbon accumulation in Lompolojänkkä seems to have increased following the change in the vegetation. However, the inferred increase might largely reflect an incomplete level of decomposing characteristic to surface peat. In contrast to the peatland margins, no drying signals or vegetation changes were observed in the central parts of Lompolojänkkä. This variation within a single peatland highlights the heterogeneous nature of peatland climate responses and carbon dynamics.

The Red List Index (RLI) has widely been recognized as a useful tool in keeping track of extinction risk trends of large taxa. The RLI is an index based on IUCN’s threat categories. Functional diversity (FD) is a way of measuring biodiversity that describes species´ traits that are linked to species´ ecological roles. In this work I have mapped the spatial distribution of the RLI and functional diversity for Finnish vascular plants. I first produced species distribution models (SDMs) for all 1194 species of vascular plants in the Finnish Red List 2010 based on records from the Kastikka and Hertta databases and environmental data. A functional tree incorporating 971 of those species was calculated using seven functional traits. The traits that I used were life form, maximum plant height, seed mass, seedbank longevity, life span, specific leaf area (SLA), and leaf dry matter content (LDMC). The trait data was gained from the databases Leda and TRY. Based on the SDMs, the functional tree, and the Finnish Red List, taxonomic and functional diversity and RLI were mapped for the whole of Finland using 10 x 10 km cells. This was the first time FD and RLI were mapped for vascular plant species across Finland. Null models were used to compare observed values with the ones expected if species (and consequently traits) distributions were random accross the country. Taxonomic diversity (TD) was higher than expected in southern Finland and lowest in northern Finland, suggesting a strong latitudinal gradient. TD correlated with the same environmental variables as FD. Thus, it is likely that both TD and FD are dirven by the same environmental variables. FD was higher than expected in southern and western Finland and lower in the northern and eastern parts of the country. A strong environmental filtering in the north might cause low FD by limiting species´ distributions within many clades and favouring species with similar traits that allow them to survive in extreme conditions. In southern Finland, competitive exclusion might limit the co-existence of species with similar traits, thus increasing trait divergence. The RLI values were lowest in the Åland islands, along the southern coast, in a few sites in eastern Finland (e.g. Koli and Kuusamo areas), around Kemi and the Gulf of Bothnia and in Kilpisjärvi. Thus, these sites have high concentrations of threatened species. The low RLI sites correspond well with areas with either limestone or dolomite deposits, which explains why many of these areas are floristically unique and present high concentrations of threatened species. In addition, many of the sites with low RLI are geographical extreme areas in Finland, corresponding to the distribution limits of many species. The RLI was high in Ostrobothnia and in large parts of Lapland. In Ostrobothnia, centuries of forest management and a homogenous bedrock and topography have resulted in a vascular plant community based mostly on common species. It is possible, that regional extinctions have happened in Ostrobothnia already before red listing measures began, thus explaining the high RLI values today. On sites with more variety among habitats and bedrock, the RLI values were significantly lower than in the rest of Lapland, suggesting that the high RLI values for parts of Lapland are due to homogeneous plant communities in the northern boreal forests that host only few threatened species. The spatial distribution of the RLI and functional diversity for vascular plants in Finland were mapped for the first time. A strong latitudinal gradient was found for TD and FD. Low RLI values were found on calcareous soils and on geographic extremes in Finland. To track possible changes in the RLI it would be crucial to remap the RLI in 2019 when the next Finnish Red List is published. A comparision between this work and the remapping based on the 2019 assessment would track changes in the extinction risk across Finland. The current limitation with RLI is that it only considers taxonomic diversity. However, in future work it is possible to incorporate the functional tree used in this thesis into RLI to calculate a functionally weighted RLI.

Ornamentit ovat hyödyllisiä kumppaniehdokkaiden arvioimisessa ja kilpailussa toisia lisääntymishalukkaita yksilöitä vastaan. Naaraiden ornamenttien kehittymistä edistää koiraan korkeat lisääntymiskustannukset, kuten poikasten hoito ja pesän rakentaminen. Kehitystä rajoittavat naaraan ornamenteista koituvat kustannukset, jotka rajoittavat jälkeläisten määrää ja selviytymistä munasoluihin käytettävissä olevien resurssien kautta. Ihmisten toiminnasta johtuva lisääntyvä rehevöityminen vähentää näkyvyyttä ja siten haittaa ornamenttien käyttöä niin kumppaneiden houkuttelussa ja arvioinnissa kuin samaa sukupuolta olevien kilpailussa. Lisääntymiskauden aikana sekä kolmipiikkikoirailla että naarailla on havaittavissa ornamentteja. Itämeren rehevöitymisen on havaittu vaikuttavan kolmipiikkien lisääntymiseen usealla tavalla, kuten seksuaalivalinnan heikkenemisellä ja muutoksilla munien kuoriutumistodennäköisyyteen. Kolmipiikkinaaraiden ornamentin käyttötarkoitukset ja rehevöitymisen vaikutukset siihen ovat kuitenkin vielä tuntemattomia. Tutkin rehevöitymisen vaikutusta kolmipiikkinaaraan ornamenttiin avoimessa ja suojaisassa habitaatissa sekä ornamentin yhteyttä naaraan hedelmällisyyteen. Selvitin, vaikuttaako ornamentin voimakkuus naaraan kumppaninetsintäaktiivisuuteen, koska ornamentin on aiemmin havaittu kertovan lisääntymismotivaatiosta. Lisäksi testasin, suosivatko koiraat ornamentillisia naaraita ja vaikuttaako näkyvyys koiraan valintaan. Tulosteni mukaan naaraan ornamentti ei ilmaissut naaraan hedelmällisyyttä eikä habitaatin suojaisuus vaikuttanut ornamentin kehitykseen. Ornamentin ylläpito ja kumppaninetsintä ovat molemmat resursseja kuluttavia toimintoja. Saadakseen kumppanin heikompilaatuisen naaraan on mahdollisesti panostettava enemmän koiraan etsimiseen kuin ornamenttiin ja siksi havaitsin heikompiraitaisten naaraiden olevan aktiivisempia kumppaninetsinnässä. Naaraiden ornamentti voimistui naaraan ollessa kosiskelevan koiraan seurassa. Kolmipiikkikoiraat suosivatkin ornamentillisia naaraita ja kykenivät valitsemaan ornamentillisen naaraan näkyvyyden heikkenemisestä huolimatta. Toisaalta näkyvyyden heikkeneminen vähensi koiraan kosiskeluaktiivisuutta. Kolmipiikeillä molemmat sukupuolet käyttävät ornamentteja kumppaninvalinnassa, mutta naaraan ornamentin hyödyt koiraalle vaativat vielä lisää tutkimusta.

Introduction: High anthropogenic pressure exercised on the Baltic Sea causes a decline in valuable reproduction areas of coastal fish, such as the northern pike (Esox lucius L.). Hence, the conservation and restoration of the reproduction areas of pike are increasingly of importance. The Kvarken Archipelago, located in the Gulf of Bothnia, presents valuable reproduction habitats for fish. The pre-flads, flads, glo-flads and glo-lakes provide warm and sheltered areas that are preferred by spring-spawning fish, such as pike. However, the precise environmental factors influencing pike reproduction in the region have not yet been identified. In this study, different environmental factors influencing pike reproduction in the Kvarken Archipelago were assessed. Furthermore, as technology advances, there is a need to evaluate the use of new techniques alongside the generally time consuming and expensive traditional research methods applied for surveying the pike reproductive areas. Henceforth, the present study assessed the suitability of the high-resolution aerial photography for identifying potential reproduction areas of northern pike. Methods: The data of pike fry density, the vegetation, the abiotic and biotic environmental factors, as well as the aerial images of the 45 sampling sites were collected by Natural Resources Institute Finland and Metsähallitus Parks and Wildlife Finland as part of the Kvarken Flada -project. Pike fry were sampled with a flat dipnet amongst vegetation along a 100 m sampling line during spring. Concurrently, the vegetation, the occurrence of sticklebacks (Gasterosteidae) and the abiotic factors affecting water quality, including salinity, pH, oxygen content and turbidity were determined. The temperature was recorded with temperature loggers from early spring until late summer. The temperature sum for June showed the greatest effect on pike fry densities and was thus used in the analyses. The archipelago zones, which are based on previously modelled temperature sums, were defined for the sampling sites in the geographic information system (QGIS). Additionally, factors describing the morphology, the vegetation and bottom substrate coverage of the sampling sites were utilized in the analyses. The presence of pike fry was analysed with binary logistic regression. The pike fry densities were studied using non-parametric analyses due to the high number of zero observations in the data. The aerial images were taken in late summer of 2017 and 2018, when the vegetation was fully developed. The vegetation types, i.e. reed, fallen reed, wetland grasses, submerged vegetation and filamentous algae, identified in the images were compared to the vegetation data gathered during field survey in QGIS. The performance of the aerial images was assessed by calculating the accuracy, sensitivity and specificity for the different vegetation classes, first for the whole dataset and then for the sampling points with pike fry observations. Results and conclusions: This study determines two key factors defining suitable reproduction areas of pike, the temperature sum for June and the morphology of the sampling site. The results indicate that pike prefer warm and sheltered areas with suitable vegetation, such as reed and wetland grasses. In particular, glo-lakes provide favorable conditions for pike and the temperature sum for June was significantly higher in the glo-lakes compared to the pre-flads. The temperatures of the glo-lakes were constant throughout the archipelago, providing suitable conditions for pike reproduction also in the outermost archipelago. In all of the glo-lakes pike fry were observed and generally the highest pike fry densities were found in glo-lakes. However, the year class strength of pike can be affected by the possibility of the juvenile pike to emigrate from the enclosed glo-lakes back to the sea. Salinity reflects the connectivity of the site to the surrounding sea and had a significant negative effect on pike fry density. Additionally, the presence of sticklebacks affected negatively the presence of pike fry, which might be traced back to the different use of the archipelago zones and site morphologies of these species. Increasing pH negatively influenced the pike fry density. However, pike fry were observed also in the highest pH conditions and therefore pH alone is not sufficient to explain the presence and density of pike fry. Due to the small sample size of the dataset, it can be assumed that not all of the factors influencing pike reproduction were identified and thus the use of a larger dataset is recommendable in future studies. This study provides new methodological information on reproduction area surveying of pike with high-resolution aerial photography. The different vegetation classes were successfully identified from the aerial images. The seasonal differences were noticeable in the results, as in the aerial photographs taken in late summer, the vegetation was fully developed compared to the field study in early spring. Nevertheless, aerial photography proved to be an effective method for identifying reproduction areas of pike based on the vegetation. Furthermore, reproduction areas in need of restoration could be assessed with aerial photography.

Peatlands are roughly divided into bogs, which are dry and ombotrophic, and fens, which are wet and minerotrophic. Bog vegetation typically consists of dwarf shrubs, lichens, and especially of peat forming white mosses Sphagna spp. White mosses, yet different taxa, also occur on fens and are accompanied by various sedges Carex spp. and Eriophorum spp. Human activities are changing the climate. These activities increase greenhouse gas concentrations in the atmosphere, which in turn causes global climate warming. It is not yet resolved how the warming is affecting the ecosystems and what are the response mechanisms. Peatlands cover a considerable area, i.e. 4 million square kilometres of the Northern hemisphere, including continuous, intermittent or sporadic permafrost, the latter especially vulnerable to thawing. Since their formation following the deglaciation ca. 11 700 years ago, the Northern hemisphere peatlands have acted as carbon sinks storing great amount of atmospheric carbon as accumulated peat. This is due to the slow decomposition rate under cold climate. Simultaneously peatlands release carbon back to the atmosphere via microbial activity, which is largely regulated by hydrological conditions and associated plant composition. Carbon dioxide (CO2) release in aerobic conditions happens mainly through respiration of the living organisms, while in wet anaerobic conditions methane (CH4) is released due to methanogenic processes. The rate of peat, i.e. carbon, accumulation and release has varied over time due to for instance prevailing climate conditions. Mire surface is a mosaic of hydrological and thus vegetational patterns. Different taxa thrive in different growing conditions and furthermore, respectively, can affect the carbon dynamics. While long-term autogenic succession changes surface vegetation and microtopography, also allogenic forcing, such as climate and warming alter habitat conditions and for instance lead to permafrost thawing. Currently, especially thawing of permafrost is a concern worth noticing. Thawing ice might cause water saturated conditions, which in turn may lead to increase in methane emissions. Past changes in prevailing vegetation can be studied through stratigraphical examinations of peat. The accumulated peat layers reflect drier and wetter conditions, and these can be identified by distinguishing the remaining plant macrofossils. The reconstructed changes in past vegetation can be dated with radiometric methods and then compared with paleoecological climate data or meteorological measurements to evaluate if the changes in vegetation and carbon accumulation correspond to changes in climate. In this study I investigate the relationship between past changes and peatland vegetation, carbon accumulation and climate. The focus time period covers the last centuries. My thesis consists of two case studies from northern Sweden permafrost peatland areas, Abisko and Tavvavuoma. The two main taxa, which dominated the plant assemblage were Sphagnum fuscum and Dicranum elongatum. In Tavvavuoma the plant composition varied more than composition in Abisko. Also, the oldest peat section was from Tavvavuoma, where bottom age of the peat section was ca. 8000 years old. The peat and carbon accumulation data indicate similar patterns for both study sites. No clear signs of the generally warmer Medieval Climate Anomaly or colder Little Ice Age were found in my data, but at both study sites the warming after Little Ice Age has shifted vegetation towards a drier assemblage and this has affected the carbon accumulation rates positively especially since the turn to 20th century. According to my data, it can be suggested that vegetation composition and carbon accumulation follow the climatological and thus hydrological conditions, thus my results are in accordance with earlier studies.

Sindbis virus belongs to the Alphavirus genus and it has spread around the globe. Sindbis virus is transmitted by mosquitoes and spread birds. Mosquitoes from Culex and Culiseta genera are able to spread Sindbis virus. In Finland game birds from Tetrao genus have been observed to act as host for Sindbis virus thus enabling viral amplification. In Finland Sindbis virus causes annual disease called Pogosta disease. Typically, Pogosta disease occurs from August to September. Symptoms of Pogosta disease include for example joint pain, arthritis, rash and fever. Pogosta disease is endemic in Finland and known endemic regions are e.g. Ilomantsi region. Even though Sindbis virus causes annual disease in Finland there is currently only six Sindbis virus strains isolated from Finland. These isolations were done in 2002 and in 2005. There is a need for new data. In this master thesis the aims were to describe how two new Finnish Sindbis virus strains were isolated and to compare them to each other and to other Sindbis virus strains isolated from Finland and around the globe. Mosquito samples were collected from Ilomantsi region in 2018 summer. Serum samples from serologically diagnosed patients with Sindbis virus infection were obtained from HUSLAB and included in this study. The mosquito and patient serum samples were cultivated on cells and later virus isolates were plaque purified. Conventional nested reverse transcriptase polymerase chain reactions (RT-PCR) for Alphavirus and Bunyavirus genera were used in order to screen mosquito and patient serum samples for viruses. Later a Sindbis virus specific real time reverse transcriptase PCR was used to test mosquito and patient serum samples. Cell cultures were also tested with immunofluorescence assays. Isolated Sindbis viruses were sent for next generation sequencing and based on that a phylogenetical tree was constructed. The phylogenetical tree represents the new Sindbis virus strains relation to Finnish and to other Sindbis virus strains around the globe. Mosquito samples were morphologically identified and subjected to genetic species identification analysis via COI sequences. These COI PCR products were sent for Sanger sequencing and compared to sequences in NCBI database in order to determine the mosquito species. In this master thesis two new Finnish Sindbis virus strains were isolated from mosquito and from human serum sample. This is the first time in Finland when Sindbis virus has been isolated from human serum sample. These two new Finnish Sindbis virus strains differ from each other. The strain isolated from the patient sample is more closely related to German strains than to Finnish Sindbis virus strains. The strain isolated from mosquitoes is closely related to pre-existing Finnish Sindbis virus strain Ilomantsi region-2005M which is isolated from mosquitoes. These finding suggest that currently there is two different Sindbis virus strains circulating in Finland. This master thesis provides valuable information of Finnish Sindbis virus strains which can be used in future studies e.g. when studying Sindbis virus pathogenesis, distribution, relation to other Sindbis virus strains or mapping Sindbis virus prevalence in Finland.

Yersinia pseudotuberculosis voi aiheuttaa ihmiselle suolistoinfektion, yersinioosin. Se tarttuu kontaminoituneiden elintarvikkeiden välityksellä, ja Suomessa on todettu useita epidemioita viimeisen 20 vuoden aikana. Yersinia-suku kuuluu Enterobacteriaceae-heimoon, ja siihen kuuluu tällä hetkellä 18 lajia. Y. pseudotuberculosis-lajin lisäksi sukuun kuuluu kaksi ihmispatogeenia, Yersinia enterocolitica ja Yersinia pestis. Y. enterocolitica on myös elintarvikevälitteinen patogeeni, Y. pestis puolestaan tunnetaan ruton aiheuttajana. Y. pseudotuberculosis kasvaa hyvin jääkaappilämpötiloissa, jolloin nykyaikaiseen elintarvikehygieniaan oleellisena osana kuuluva kylmäsäilytys ei estä sen lisääntymistä elintarvikkeissa. Sen vuoksi onkin tärkeä tutkia tekijöitä, joilla on merkitystä Y. pseudotuberculosis-bakteerin kylmänsiedossa ja muissa stressiolosuhteissa. RNA-helikaasit ovat proteiineja, jotka avaavat kaksijuosteista RNA:ta. Niihin kuuluu useita proteiiniperheitä, mutta suurin niistä on DEAD-box-helikaasiperhe. DEAD-box-helikaaseja löytyy kaikista eliöryhmistä, ja ne osallistuvat kaikkiin RNA-metabolian vaiheisiin. Ne ovat ATP-riippuvaisia helikaaseja ja ne kykenevät avaamaan vain lyhyitä kaksijuosteisia alueita. Y. pseudotuberculosis IP32953- genomi sisältää viisi DEAD-box-helikaasia koodaavaa geeniä, csdA, dbpA, rhlB, rhlE ja srmB. RhlB osallistuu mRNA-molekyylien hajottamiseen osana RNA-degradosomia. Muut proteiinit osallistuvat pääasiassa ribosomin rakentumiseen. Escherichia coli -bakteerilla aiemmin tehdyn tutkimuksen perusteella tiedetään, että CsdA:n ja SrmB:n puuttuminen soluista saa aikaan kylmäherkän fenotyypin. CsdA:n roolia on tutkittu myös Y. pseudotuberculosis-lajilla, jossa toimimaton CsdA heikentää kasvua kylmässä. Tämän tutkielman tarkoituksena oli tutkia RNA-helikaasien vaikutusta Y. pseudotuberculosis IP32953-kannan kasvuun erilaisissa stressiolosuhteissa. RhlE-, DbpA- ja SrmB-deleetiomutanttikantoja kasvatettiin optimilämpötilan (28 °C) lisäksi kylmässä (3 °C), korkeassa suolapitoisuudessa sekä alhaisessa ja korkeassa pH:ssa. Kasvun aikana mitattiin bakteerien kasvua OD600nm-mittausten avulla, ja aineiston perusteella kannoille piirrettiin kasvukäyrät kaikissa olosuhteissa. Lisäksi aineistosta laskettiin käyrän alle jäävä pinta-ala, jonka perusteella tutkittiin kasvuerojen tilastollista merkitsevyyttä Studentin t-testillä. Kannoille määritettiin myös kasvunopeudet eri olosuhteissa. Deleetiomutanttien kasvussa huomattiin eroa alhaisessa lämpötilassa, jossa kaikki deleetiomutanttikannat tilastollisesti merkitsevästi kasvoivat villityypin kantaa huonommin. Lisäksi ΔsrmB -kanta kasvoi tilastollisesti merkitsevästi heikommin optimilämpötilassa ja korkeassa pH:ssa. Näyttääkin siis siltä, että DEAD-box-helikaasit ovat Y. pseudotuberculosis-bakteerilla suuremmassa roolissa kuin E. coli-bakteerilla, ja niitä tarvitaan erityisesti alhaisissa lämpötiloissa.

Epithelial cells line the surfaces of organs and tissues in a continuous and tightly packed manner, thereby functioning as a protective barrier between the tissue and the external environment known as the epithelium. During development, the epithelium undergoes a series of morphogenetic events which alters the shape and size of epithelial cells, enabling them to perform tissue specific functions in mature tissue. During morphogenesis, cells sense the mechanical forces and establish polarity through cell proliferation and rearrangement according to morphogenetic signalling pathways. This manoeuvre is achieved by the underlying actin cytoskeleton network which enables cells to resist the tension and stresses of morphogenesis via alteration of filament dynamics and network architecture. In vivo, numerous actin-regulatory proteins generate various polymerized forms of straight, branched, or contractile actin-myosin filaments, regulating dynamic actin filament turnover. The robust actin cytoskeleton provides the cell with protrusive and contractile forces that enable cells to migrate, maintain, and change its shape and form during morphogenetic events. Actin filament depolymerization is accomplished by ADF/cofilin (Drosophila homolog twinstar) binding to actin monomers (G-actin) and actin filaments. However, ADF/cofilin alone is not very efficient in promoting disassembly of actin monomers, especially in subcellular regions where ADF/cofilin is highly concentrated. AIP1 (Drosophila homolog flare) then enhances actin depolymerization via preferential binding to ADF/Cofilin rich regions in vitro. The aim of my thesis was to study the localization and roles of AIP1 and cofilin in follicular epithelium during Drosophila oogenesis. My results showed that Actin-Interacting-Protein-1 (AIP1) was expressed throughout oogenesis. AIP1 expression was increased in cell type-specific manner and AIP1 showed spatiotemporal localization in follicular epithelium during oogenesis. Silencing of AIP1 led to accumulation of ectopic F-actin aggregates, localization of which may reflect the cellular sites of dynamic actin reorganization in the follicular epithelium. My results also indicate that AIP1 may be indirectly responsible for maintaining epithelial integrity as its silencing resulted in formation of epithelial gaps throughout follicular epithelium. Also delays in border cell migration were observed. Considering the above, understanding how AIP1 functions in Drosophila morphogenetic events would therefore pave the way for a greater understanding of how this protein works in other organisms. The knowledge gained may also be used to extend the current understanding of the role of actin binding proteins in diseased states.

The increased rates of population growth and urbanization worldwide raises the question of food security and self-reliance in cities. In view of this situation, in recent years there has been a re-emergence of urban agriculture in its traditional form and in new variations, such as on urban rooftops. A number of rooftop urban farms exist in the world; however, very few studies have been done to establish the quality of crops they produce, specifically concerning the concentrations of contaminants. The main purpose of this study was to investigate levels of contamination in edible plants grown on urban rooftops. I determined concentrations of polycyclic aromatic hydrocarbons (PAH) and trace metals in the biomass of three types of horticultural crops grown in the city of Helsinki, Finland. Lettuce, radish and peas were planted on five rooftops in various areas of Helsinki and control samples were acquired from local food stores and markets. Both groups of crops were analyzed for concentrations of 11 trace elements using the Elan 6000 ICP-MS and 16 PAHs using Shimadzu GC-MS-QP2010 Ultra system with the AOC-20i /AOC-20s autosampler. Additionally, lettuce and pea samples from the roofs were analyzed washed and unwashed to establish levels of particulate contamination on the surface of plants that can be mechanically removed through washing. Results obtained suggest that concentrations of PAHs and trace metals in rooftop vegetables in Helsinki are very low and the differences in their concentrations compared to control (store) samples are insignificant. This demonstrates that the consumption of vegetables produced in uncontaminated soil on urban roofs in Helsinki is safe. All samples showed concentrations well below the safety limits for heavy metals and PAHs established in the European Union (EC, 2006). Finally, there was a difference in concentration of PAHs and trace metals between washed and unwashed samples, however most of the results did not show statistical significance.

Social behaviour can be divided into neutral, positive, and negative, depending on the social context. Positive social behaviour involves affiliative prosocial interactions that encourage social and emotional cohesion. Rat (Rattus norvegicus) is a globally distributed common rodent species adapted to living near humans. Rats are intelligent and social animals with reciprocal prosocial behaviour. However, research on the social behaviour of rats is concentrated in laboratory settings and very little is known about the social behaviour of free-living rats. Rats arouse strong prejudice in humans and are considered aggressive. Despite a long history of coexistence, there are still strong conflicts between humans and rats. In this study, I used camera trap data to investigate the types of social behaviour in free-living rats and the time allocation of different behaviours. I investigated how the rats' behaviour is divided into socially neutral or positive and negative behaviour in relation to the total time spent on the behaviour. I also investigated the types of social behaviour that occur when rats approach each other and the frequencies of these different behavioural models. For the behavioural analyses, I used data-driven ethograms that I made and the behavioural analysis software BORIS. I found that the majority (over 96.2 %) of the social behaviour of the free-living rats in my study population was neutral or positive behaviour as measured by the duration of the behaviour categories. I also found that the most significant proportion of social behavioural models in rats was socially neutral or positive. Agonistic behavioural models were rare and occurred mostly between adults. In contrast, rats exhibited a moderate amount of prosocial behaviour, particularly in the form of food sharing and muzzle touching. My study brings new information to the limited previous research on the behaviour of free-living rats. The results suggest that most of the social behaviour in free-living rats would be neutral or positive behaviour, and agonistic behaviour in rats would be relatively rare. To the best of my knowledge, this work is the first study to analyse the social behaviour of free-living rats from camera trap data. Objective research data on the social behaviour of rats may mitigate prejudice against rats and attitudes towards rats may become more positive. This can mitigate conflict between humans and rats and promote peaceful coexistence. This work can be used as a pilot for future studies. The information this work provides can also be used, for example, to educate people about their attitudes towards rats.