Browsing by study line "no specialization"

Pohjoisilla soilla on suuri merkitys globaaleissa biogeokemiallisissa kierroissa niiden kerrostaman ja vapauttaman hiilen vaikutuksesta. Ilmastollisten tekijöiden on todettu olevan yhteydessä suon hydrologisiin vaihteluihin, kuten kuivumiseen, vettymiseen, routaantumiseen tai roudan sulamiseen. Muutokset suon hydrologiassa ovat menneisyydessä heijastuneet vuorovaikutteisesti soiden kasvillisuuteen ja niiden rooliin maailmanlaajuisesti merkittävinä hiilinieluina. Pohjoisten ikiroutasoiden ainutlaatuinen ja rikas habitaatti on vaarantunut nykyisen ilmaston lämpenemisen myötä. Maisterintutkielmani tavoitteena on arvioida mahdollisia ilmaston lämpenemisen aiheuttamia vaikutuksia pohjoisiin soihin tutkimalla viimeisten vuosisatojen aikana tapahtuneita muutoksia suokasvillisuudessa. Tutkielmassa selvitin, miten tutkimussuoni kasvillisuus on muuttunut ja millaisia yhteyksiä voidaan havaita eri ilmastovaiheiden merkittävimpiin lämpötilan muutoksiin. Keskityin analysoimaan näitä muutoksia kasvimakrofossiili-analyysin avulla. Näytesarjat ajoitettiin radiometrisin menetelmin. Tulokset osoittivat tutkimussuon käyneen läpi kuivan kasvillisuuden vaiheita sekä ilmastohistorian lämpiminä että kylminä ajanjaksoina. Nykypäivän lämpenemisen aikana eri näytepisteissä on tapahtunut sekä kuivumista että siirtymiä kosteaan suoekosysteemiin ikiroudan sulamisen jälkeisinä ajanjaksoina. Tutkimukseni tulokset auttavat osaltaan ymmärtämään ympäristössä ja ilmastossa tapahtuvien muutosten kompleksista vaikutusta pohjoisiin suoekosysteemeihin. Tutkimuksen perusteella voidaan arvioida nykyisen ilmastonmuutoksen mahdollisia vaikutuksia tutkimussuohon, sekä rinnan muiden tutkimusten kanssa yhteyksiä pohjoisten soiden tulevaisuuden hiilitasapainoon ja suuren mittakaavan biogeokemiallisiin kiertoihin.

Lichens are symbioses between fungi, photosynthetic algae and other organisms. The fact that several different fungi may occur in the same lichen thallus adds a further dimension to the diversity of these miniature ecosystems. Calicioids are a polyphyletic group of predominantly lichenised fungi which includes many species with stalked ascomata, topped with a persistent spore mass (mazaedium). One such species is Chaenotheca chrysocephala, a relatively common crustose lichen with a wide distribution. The lichenicolous fungus Chaenothecopsis consociata grows on the thallus of C. chrysocephala and is generally considered to be a parasite. This study aims to map the temporal and geographical distribution of C. chrysocephala and C. consociata in Europe in order to find out whether the parasite was present there before the year 1942, when the species was described, and to identify possible patterns which may affect the population dynamics of these two species. This study found that C. consociata was indeed present in Europe before 1942, at least in Norway, Sweden and Finland. Additionally, the percentage of infected C. chrysocephala thalli seems to have increased in Europe since the parasite was first found. The GBIF dataset showed a significant increase in infected C. chrysocephala thalli in northern Europe (N-EU) compared to central-southern Europe (CS-EU). Although the exact reason is unclear, this increase may be related to differences in forest structure across Europe. Firstly, the host lichen seems to prefer Picea and Pinus as its substrate, these being typical trees of needleleaf forests in Europe. Furthermore, the decrease of old-growth forest stands in Sweden and Finland may have reduced suitable habitat for the host, while the concurrent increase of disturbed stands may have favoured the dispersal of the parasite.

Birdsong is information, communication and a target of sexual selection. Song complexity is the variation in bird song structure. Within-song complexity is variation in song components, in number and order of syllables and phrases. Song complexity is an honest trait under sexual selection and competition for mates increases it. When species expands its range front to a new area, the population density is low in the beginning. Males in the new population do not need to compete as hard as before, because population density is decreased, which decreases song complexity. Many warblers have complex songs and they do not have a colourful plumage. It is well possible that song complexity is the main target of sexual selection in warblers. The purpose of this study was to investigate if there were differences in song complexity in Eurasian reed warblers (Acrocephalus scirpaceus) breeding at their range front in Finland. The population of Finland is 100 years old and the population density is still decreased in compared to Central Europe. My hypothesis was that reed warblers would sing less complex songs at lower densities as competition for mates is low. I used song recordings of 51 reed warbler males, which I recorded during the breeding season 2019 in song complexity analyses. Recordings were from South Finland from 14 locations in 6 municipalities. Most of the recording places were coastal reedbeds. A couple of recording places were reedbeds in inland ponds and reedbeds in a flooded forest. I counted the male densities within 50 m and 200 m radius around the recorded males using Google Maps. I took account the males which were at least 20 m away from each other and were there in the same week than the recorded male. I extracted four within-song complexity variables from the recordings: Total number of syllables, number of syllable types, number of syllable transitions and mean frequency bandwidth. I measured song complexity with spectral analyses using Koe, a bioacoustic software. I did next analyses with R to see if there is association between local density and complexity. I found that one of the song complexity variables, total number of syllables, was significantly positively associated with the density of singing males within 200 m radius. The other variables were not significantly associated with male density, but number of syllable types and number of syllable transitions showed a similar relationship with singing male density within 200 m. Previous studies support the hypothesis that higher local density can increase some aspects of song complexity, for example number of syllables or length of phrases. Some males did not have neighbours within 50 m. Density within 50 m had no significant relationship with song complexity variables. However, mean frequency bandwidth, total number of syllables and number of syllable types showed more variation when neighbours were present, which suggest that males increase their effort when they have competition. Finally, I found that the number of syllable transitions decreased as the breeding season progressed. This could be explained with younger birds coming to breed later or with paired males singing less.

Anthropogenic activity has enhanced global warming at alarming rates, causing temperatures to increase and heat waves to occur more frequently. The effects of global warming are prominent in aquatic ecosystems, particularly in the Baltic Sea. Temperature increases and fluctuations in the Baltic Sea create a changing environment and this can affect inhabiting species’ behaviors, specifically behaviors during reproduction. Reproductive behavior influences both the number and quality of offspring born into a population therefore making behavior changes during reproduction important to study. The three-spined stickleback (Gasterosteus aculeatus), an ectothermic animal, inhabits the Baltic Sea and is an ideal species to study reproductive behavioral changes. Although previous studies have researched three-spined sticklebacks in changing environments, none had specifically looked into the effects of rising temperatures and temperature fluctuations on male three-spined stickleback reproductive behavior. The three-spined stickleback is of particular interest because it reproduces in shallow waters which tend to be more affected by temperature changes. In this study, I aimed to investigate behavioral responses of stickleback males to higher temperatures and to temperature fluctuations during reproduction, as well as the consequences the responses have for reproductive success and the viability of offspring. In order to see how this species would cope with rising temperatures and heat waves during reproduction, a comparative climate chamber experiment was executed in Southern Finland at Tvärminne Zoological Station. Males were housed in either 19°C or 14°C for two breeding cycles, and for the second breeding cycle eight males switched temperatures to experience a temperature fluctuation. Results show that during reproduction, three-spined sticklebacks respond to higher temperatures with increased courtship activity, increased parental activity, quicker breeding cycles, and more weight lost. Parental care activity in constant high temperature decreases from the first to the second breeding cycle, while parental activity in constant low temperature increases. During temperature fluctuations, males experiencing a rise in temperature increase their parental care activity, while males experiencing a drop in temperature demonstrate the opposite. However, no significant consequences of temperature and temperature changes for reproductive success and the viability of offspring were detected during the two breeding cycles. Overall, the results of this study would indicate that the three-spined stickleback will prove to be a resilient species, and maintain population growth in the face of increased temperatures and temperature fluctuations in the Baltic Sea.

Global surface temperature is increasing at an alarming rate. Local populations can cope with the change, if they have adaptive potential to face the new thermal regime. Hybridization with a closely related lineage is one potential source of adaptive genetic variability. My thesis aimed to investigate thermal adaptation by looking into thermal tolerance differences between two mound-building wood ants Formica polyctena and Formica aquilonia and their hybrids. The two parental species have distinct distributions: F. aquilonia can be found in Northern Europe while F. polyctena is distributed from Central Europe to Fennoscandia. The samples for this thesis were collected from a relatively small area in southern Finland and Åland Islands. Aim of my thesis was to clarify whether the two parental species have distinct thermal tolerances, which would reflect the differences in their distributions. I also tested whether hybrid individuals have wider thermal limits since they have alleles from both northern and southern parental species and could therefore show adaptive potential. I tested thermal tolerance differences with two temperature assays: heat-knockdown resistance and chill-coma recovery. I hypothesized that F. aquilonia would express more cold-tolerant thermal limits whereas F. polyctena would express more heat-tolerant limits. My results showed that the parental species differed in their thermal tolerance and expressed thermal limits which reflected their distribution. These results support the thermal adaptation hypothesis: parental species expressed thermal limits that reflected the thermal environment in their native habitat. The results also showed that hybrids could not combine the thermal tolerance of both parental species as they did not have wider thermal tolerance than parental species. Intriguingly, dry weight had a significant role in thermal tolerance, bigger ants coping better with higher temperatures. These results contribute to building up knowledge on the outcomes of hybridization and the potential that species possess in coping with the environmental change. Wood ants are keystone species in boreal forests and the findings of my thesis shed a light on the changes in population dynamics for these species in the face of global climate change.

Trace element analysis is a useful tool for the study of migration and migratory connectivity in birds. Trace elements are present in the environment and, through the food chain, can be incorporated into tissues such as growing feathers. Since the concentrations of elements remain stable after the feather has stopped growing, and trace element abundances can vary at very small geographical scales, the concentration of trace elements in feathers can provide information on the location where a feather was moulted. Trace element analysis is still rarely used and there are important gaps in our understanding of how trace elements can vary at different organizational levels such as within a feather, between individuals or even between species. It is also not clear if large-scale geographical patterns can be detected by the method, as trace element concentrations can vary a lot even at small scales, which could make it impossible to see larger-scale patterns. To address that, my objectives were (1) analysing the variability of trace element concentrations within feathers, between individuals and between species and (2) determining whether trace element levels differed in feathers grown in Africa compared to feathers grown in Europe. This would shed insight on the suitability of trace element analysis for the study of migration and migratory connectivity. I analysed the concentration of 18 trace elements in the rachis of feathers from willow warblers (Phylloscopus trochilus) and barn swallows (Hirundo rustica) collected in Finland. I plucked three belly feathers from willow warblers collected in spring, whose feathers had grown in Africa. These feathers were used to analyse variability of trace element concentrations within feathers and between individuals. They were also compared to feathers plucked from barn swallows collected in spring (two feathers per bird) to analyse variability between the feathers of two species that winter in the same region. Finally, African-grown feathers of willow warblers were compared to European-grown feathers of willow warblers collected in autumn (two feathers per bird) to look for differences in trace element concentrations in feathers grown on two different continents. Trace element concentrations were analysed using Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS), which allowed to measure concentration at hundreds to thousands of points along the feather rachis. The concentration of each of the 18 elements was used as the response variable in linear mixed models (LMM). To model variation in concentration within the feather I used location along the feather rachis as the explanatory variable and explored how well it predicted concentration of each element. To compare variation between feathers and individuals I fit models including and excluding the feather and individual that each measurement belonged to as random effects and compared them using AIC. To compare between willow warbler and barn swallow feathers grown in Africa I included species identity as the explanatory variable and looked at how the concentration of the 18 elements differed between them. Finally, I followed the same approach to compare willow warbler feathers moulted in Africa and in Europe. For most elements there was little variation along the feather rachis, with concentration remaining stable from feather base to tip. Zn and S showed an increase in concentration starting at the feather base until the central part of the feather and then remained constant toward the tip. Feathers belonging to the same individual showed mostly similar trace element concentrations, although there were exceptions and differences between feathers of different willow warbler individuals were also little. 10 out of 18 elements showed significant differences in feathers of willow warblers and barn swallows grown in Africa. Eight of those elements were more abundant in willow warbler feathers, while only two were more abundant in barn swallow feathers.12 out of 18 elements showed significant differences between their level in African-grown feathers and European-grown feathers. Of those, 10 elements showed higher levels in African-grown feathers, while only two were higher in European-grown feathers. My results suggest that trace elements can show variation at different organizational levels. Variability within feathers was important in at least two elements, which could be caused by physiological processes. This means that when designing sample collection for trace element analysis, unless we know that an element does not vary along a feather, it is important to consider which part of feathers we are sampling. Variability between feathers and individuals was lower than within feather variability, but still significant. Future studies should account for possible within and between individual differences in their design. Differences between barn swallows and willow warblers were large, which was expected based on the literature. It is still unknown what drives these differences between species: some explanations suggested have been physiological and dietary differences or differences in their habitats. I also found clear differences between feathers of willow warblers grown in Europe and Africa. While the exact cause is still not known, this means that at least in willow warbler feathers it is possible to study large scale geographical patterns by trace element analysis. LA-ICP-MS has potential to be a powerful tool to study migration and migratory connectivity in birds. It allows to detect variation in trace elements at continental scales while also allowing to control for different levels of variability in the study design. I encourage researchers to adopt its use in their research.

Prey defend themselves from predators using a range of tactics, including evolving distasteful compounds and advertising their unprofitability with aposematic warning signals. Therefore, before attacking a potential prey, predators need to assess whether it is palatable and profitable to consume. Previous studies have demonstrated that predators can rely on personal experience (personal information) and/or observe the foraging behaviour of others (social information) to assess prey profitability. ‘Social avoidance learning’, where predators observe a negative foraging experience associated with beak wiping, has been suggested to be important to explain how novel warning signals evolve. However, in previous studies observers saw a very strong “disgust response” of the demonstrators, when in fact there is variation in how strongly birds respond to unpalatable food. Therefore, to understand how social avoidance learning can work in nature I investigated how blue tits (Cyanistes caeruleus) use social information from demonstrators that show a weaker response to unpalatable food. I provided social information to observers using video playback of a demonstrator bird consuming a novel conspicuous prey item and showing: (1) a strong disgust response (65-95 beak wipes) as in previous studies, (2) a weak disgust response (12-25 beak wipes), or (3) no disgust response (control, no beak wiping). Next, I investigated birds’ foraging choices using a miniature novel world protocol where birds encountered novel aposematic (conspicuous and unpalatable) and cryptic (camouflaged and palatable) prey. Tested individuals consumed fewer aposematic prey after seeing a strong response but seeing a weak response did not influence their foraging choices. My results, therefore, suggest that information about novel aposematic prey may be less likely to spread socially than previously thought. However, more work is needed to determine both the availability and salience of graded social information.

Tutkielmassani kartoitan Ahvenanmaan hoikkatytönkorentopopulaation (Ischnura elegans) Wolbachia infektioita. Lisäksi pyrin selvittämään, löytyykö samaa infektiota korentoja loisivilta vesipunkeilta (Hydrachnidia). Wolbachia on niveljalkaisilla yleisesti esiintyvä endosymbioottinen bakteeri. Bakteerin yleinen esiintyminen johtuu sen kyvystä manipuloida isäntänsä kelpoisuutta, jolloin infektoidut naaraat lisääntyvät tehokkaammin. Bakteeri leviää tyypillisesti maternaalisesti iturataa pitkin, mutta voi levitä myös lajilta toiselle horisontaalisesti. Aikaisempien tutkimusten perusteella Manner-Suomen ja Ruotsin hoikkatytönkorentopopulaatioilla esiintyy yleisesti Wolbachia infektioita, toisin kuin Ahvenanmaalla, josta bakteeria ei löydetty lainkaan. Otanta Ahvenanmaalta oli kuitenkin pieni, eikä se siten välttämättä edusta populaation varsinaista infektiostatusta. Lisäksi korentoja loisivien vesipunkkien mahdollisia Wolbachia infektioita tai niiden potentiaalista roolia bakteerin levittämisessä on tutkittu aikaisemmin hyvin vähän. Tutkielmassani analysoin hoikkatytönkorentoja ja niiden punkkeja, jotka on kerätty eri puolilta Ahvenanmaata kesäkuukausien aikana vuosina 2021, 2022 ja 2023. Näytteiden Wolbachia infektiostatuksen selvittämiseksi käytin PCR-tekniikkaa, monistaen yhden mitokondriaalisen lokuksen (COI) ja kolme Wolbachia lokusta (fbpA, wsp ja ftsz). Sekvenssien analysointiin käytin MEGA v.11 ohjelmaa. Laajemman otannan perusteella alle puolella Ahvenanmaan hoikkatytönkorennoista on Wolbachia infektio (41.51 %). Populaatiossa esiintyy ainakin kolmea eri Wolbachia kantaa, joista yksi vastaa Ruotsissa ja toinen Manner-Suomessa esiintyvää bakteerikantaa. Lisää tutkimusta tarvitaan selvittämään, miksi bakteeri ei ole yhtä yleinen Ahvenanmaalla kuin naapuripopulaatioissa, ja millaisia vaikutuksia bakteerilla on hoikkatytönkorennon ekologiaan ja evoluutioon. Noin puolen millimetrin pituisten vesipunkkien infektiostatus jäi epäselväksi lähinnä DNA:n eristämiseen ja monistamiseen liittyvien haasteiden vuoksi.