torstai 7. syyskuuta 2017

Are changes in solar radiation and spectral composition reflected in leaf optical properties of forest understorey species?

Sunflecks and shaded areas on the forest floor in one of
our field sites at Lammi Biological Station
In the understorey, shade-loving plants live their whole life on the forest floor. Processes like leaf reflectance, transmittance and absorbance, determine the composition of radiation that reaches the understorey. We assist to the formation on the forest floor of micro-sites with different light conditions: shade and sunflecks, a brief increase of solar irradiance that occurs in the understorey when sunlight is able to directly reach the forest floor. As a result, understorey species are exposed to a very dynamic light environment during the day, meaning that they must develop mechanisms to quickly exploit the fluctuating PAR (Photosynthetic Active Radiation) in conditions where light is limiting to growth. The plants’ capacity to assimilate carbon under different species canopy cover determines the community structure and consequently alters nutrient cycling and the forest ecosystem  functioning. As my PhD focuses on the impact of spectral composition on ecosystem processes, we thought it would be interesting to understand how this function varies as a consequence of different lights conditions to which the understorey plants themselves are exposed every day. 

The aim of this study is to monitor the response of understorey plants to the transit of a sunfleck across the predominately-shaded forest environment and to assess how the season and structure of forest canopies, affecting the quantity and quality of irradiance, moderate the photosynthetic response of understorey plants to sunflecks. I focused on four early-spring ephemeral species (Anemone nemorosa L., Oxalis acetosella L., Fragaria vesca L., Hepatica nobilis Schreb.). Furthermore, I characterised the duration and intensity of several sunflecks in forest stands with different canopy species in Finland and Spain during spring and summer 2016 and 2017. Changes in leaf properties passing from shade through a sunfleck have been monitored through time-series of chlorophyll fluorescence (measured with a Walz mini-PAM) and leaf temperature (measured with an infrared thermometer).

My PhD supervisor Matt Robson with me
observing sunflecks in our field site
Preliminary results show a very fast response of the photosynthetic apparatus to sunfleck passage, on a timescale of seconds. The photosynthetic yield changed quickly when the leaves were exposed to different light conditions and recovered quickly from its sunfleck-depression on return to shade. Furthermore, in some of the studied species we observed an increase of the photosynthetic yield just before the leaves reached the edge of the sunfleck. This suggests that the plant is primed for the arrival of the sunfleck, probably by a spectral cue. The temperature of the leaves also changed during the transit of the sunfleck, just before the arrival of the sunfleck the temperature decreased, indicating that the plant can perceived the light changes as a cue to open the stomata and increase transpiration.

A coloured-film filter over beech seedling
during a sunfleck at our filed site in Spain
In order to detect the spectral cues that might be responsible of the priming of the plants we repeated the experiment in summer 2017, but now filters have been used to manipulate the solar spectrum. This meant that we could experimentally test the plant response to different light qualities in an attempt to identify the spectral cue that enables the plant to detect the sunfleck just before its arrival. This is only a small part of my PhD but it can have very important impact on the analysis and modelling of carbon cycle in the forest ecosystem. I am looking forward to go on with my project on this interesting topic and I wish to thank Lammi Biological Station for the opportunity to perform my research and the help that I received. 

Marta Pieriste of the University of Helsinki is a 2016 grant recipient

tiistai 13. kesäkuuta 2017

Morphological and Genetic Diversity of Harpacticoids (Copepoda, Crustacea)

The extraordinary diversity of forms and life strategies of copepods makes them very convenient subject for studies of variety of fundamental biological processes. They play a significant role in every ecosystem. As the dominant secondary producers, copepods are like the linchpin of aquatic food-webs. Also, they are sensitive indicators of local and global climate change. Copepods show a complex pattern of responses to variability in environmental conditions. Their abundance within a locality appears to be correlated with temporal and spatial conditions, especially food availability. Thus, they are present in various water bodies at a certain time of the year, when conditions are most favorable for them. The rest of the time, they are lying in cysts, a special resting stage, at the bottom. My PhD thesis focuses on the morphological and genetic diversity of Harpacticoida (Copepoda, Crustacea).
Harpacticoids are small copepods (1-2mm) which inhabit every water body in the world from hot springs and leaf base to deep seas and oceans. It is well known that almost all morphological structures, life-strategy and breeding system of harpacticoid copepods change within a certain range in connection with variations of geographical and environmental factors. When gene flow among populations is restricted, natural selection can result in adaptation to local environments. A good example of this is the unique Canthocamptus staphylinus population discovered in Lake Pääjärvi in 1979. The population changed its sexual way of breeding into parthenogenesis probably due to limited food availability and short growing season.
This fact served as the starting point for my investigation of harpacticoids intrapopulation diversity. I wanted to study how populations of several species of harpacticoids differ from each other and how their isolation can affect their morphology and genetics – I wanted to understand microevolutional processes which happen in populations of this crustaceans in different water bodies. During several weeks at Lammi Biological Station I was sampled hydrobiological material and looked for harpacticoid species, especially C. staphylinus, whose breeding transition was described by Jouko Sarvala (whom I had a pleasure to meet at the Station) in his paper “A Parthenogenetic life cycle in a population of Canthocamptus staphylinus (Copepoda, Harpacticoida)” (1979).
Populations of C. staphylinus sampled in Russia, Estonia, Finland, Sweden, Norway and Switzerland showed differences in morphology of body structures and characteristics. Based on the surveys of all the varying morphological characteristics, seven morphometrical indices of the length ratios were calculated. Only four indices out of seven were statistically valid for different populations. For example, population from the Komi Republic (Russia) — the northernmost point in this study — showed the smallest body and ratios of caudal rami and legs lengths in relation to other population (see picture below). 

Our genetic studies revealed a high level of intraspecific genetic variability of C. staphylinus. Nucleotide sequences of  CO1 gene mtDNA have divided into separate clades with the divergence of about 25%. Remarkable is that the clade from Pääjärvi showed the smallest numbers of haplotype and nucleotide diversity, thus revealing a homogeneous genetic structure of population consistent with the concept of transition to parthenogenesis. Furthermore, the high level of morphological and genetic variability of harpacticoids raised the question of taxonomic structure and existence of cryptic and sibling species. Having sequenced a more conservative nuclear gene (18S rDNA), we found out this was not a complex of sibling subspecies but still one species because divergence between populations tended to zero. Thus, it is a unique case of morphological and genetic diversity (in mitochondrial DNA) within harpacticoid species which could result from a high level of plasticity and high adaptive possibilities of this taxon. 

The research revealed some cases of intraspecific and intrapopulational morphological and genetic variability of harpacticoids. This is just a small step, but it could be important as a contribution to the wide investigation of copepods phylogenetic and populational structure and response to environment. Now I investigate variability of another harpacticoid species: Attheyella crassa and Paracamptus schmeili and I am excited to continue this study. Many many thanks to Lammi Biostation staff for help and kind support.

Elena Kochanova is a 2016 recipient of a LBAYS grant. She is a PhD student of Zoological Institute of Russian Academy of Sciences, Saint Petersburg, Russia

tiistai 4. huhtikuuta 2017

Response to Bacterial Infection in a Butterfly

Parasites and pathogens are ubiquitous and represent a major threat for every individual. A well-functioning immune system therefore is crucial for every species and is under strong selection pressure. Infection risk has shown to differ depending on the season, the climate, density in the population and other environmental conditions that the organism might experience during its development. However, the risk might further differ depending on the way pathogens enter the system. If a parasite breaks through the exoskeleton of insects, which is a protective barrier, it passes the haemocoel and faces the systemic immune response, a complex interaction of cellular and humoral components. Ingestion of pathogens or spores on the other hand do have the potential to infect a host, even though they first have to overcome the gut epithelium.

I wanted to investigate the importance of bacterial infection during the adult stage in the Glanville fritillary butterfly (Melitaea cinxia) via oral infection in comparison to haemocoelic exposure of the same strain. This species is in Finland only present in the Åland Islands where it occurs in a classical metapopulation. Adults disperse from habitat patches to recolonize new patches or fly for foraging and mating. During dispersal events, individuals might encounter a higher infection risk due to changes in quality or quantity of parasites. On the one hand individuals might encounter pathogens based on wounding that might occur due to predators such as ants, spiders and parasitoids. Such wounds allow pathogens to enter directly into the haemocoel. On the other hand, dispersal reflects a resource costly event and individuals might feed on more nectar after dispersal, potentially also increasing the amount of pathogens ingested.

In a series of experiments that I conducted in the Lammi Biological Station, I infected male and female adult butterflies with a bacterial strain to investigate how this species responds to bacterial infection in general, if the two sexes would differ in their immune response and if the responses would differ depending on the way the pathogens entered their system. I measured immune gene expression levels and encapsulation rate to measure immune response and further was interested in individuals’ lifespan.

Direct exposure to bacteria via injection as well as oral exposure both had an effect on the phenotype. Lifespan was reduced for both sexes and exposure to bacteria resulted in an increase in immune gene expression. However, more immune genes responded to haemocoelic bacterial infection compared to oral exposure. Moreover, females did show higher expression levels for some immune genes, indicating that females invested more in immunity than males supporting the commonly observed susceptible male hypothesis. One explanation for the observed sex difference in immune response might be due to different strategies for reproduction. Females of this species in general live longer and deposit their eggs in several clutches throughout their lifespan, whereas males are able to increase fitness via increased number of matings. Thus they do not need to live as long as females and therefore decreased survival due to bacterial infection does not necessarily reduce their fitness. 

Further studies are needed to investigate the effect of bacterial infection on reproductive success, to investigate why sexes respond differently to infections. Infections potentially play a crucial role in this system, as infected individuals could transfer pathogens to different habitat patches, spreading a disease and thus affecting population dynamics. It will be interesting to further look into effects of other pathogens, like fungi or viral infections, to better understand immunity in this butterfly and insects in general.

Luisa Woestmann is a PhD student at the University of Helsinki and a 2016 LBAYS grant recipient

maanantai 2. tammikuuta 2017


Kesän aloittaminen toukokuun lopulla Lammin biologisella asemalla  Pääjärven rannalla oli miellyttävä kokemus. Varsinkin kun olin lupautunut esittämään kaupungin tervehdyksen vuonna 2008 perustetun Ympäristötutkimuksen Säätiön järjestämällä Ympäristölounaalla. Kutsun tarkoitus oli jalo ja ylevä: Tukea erityisesti biologisella asemalla tehtävää ympäristötutkimusta. Hämeenlinnan kaupunki on ylpeä siitä, että sen alueella toimii maan suurin yliopistollinen kenttäasema. Jo 1950-luvun alkupuolella perustettu asema on tunnettu erityisesti vesiympäristöön liittyvistä tutkimuksistaan. Aivan aseman vieressä lainehtiva Pääjärvi taitaa olla yksi maailman tutkituimmista järvistä.

Tutkijat näytteenotossa Pääjärvellä
Tätä pohtiessani mieleeni palautuivat lapsuuteni kesät 1950- ja 1960-luvuilla isäni lapsuusmaisemissa Lammilla. Näihin kesänviettoihin liittyi tietysti paljon uimista ja kalastusta Pääjärvessä. Eipä silloin nuorella pojalla ollut käsitystä siitä, miten arvokasta tietoa ja taitoa järven rannalle perustettu tutkimusasema tuottaa aikanaan maailmalle. Toinen henkilökohtainen kokemus ja tutustuminen aseman toimintaan osui työelämääni radio Hämeen toimittajana. Tuolloin sain aina silloin tällöin käydä kertomassa tutkimustuloksista radiomme kuuntelijoille ja olipa meillä yhtenä talvena yhdessä kokonainen luentosarja, jonka välitimme kansalaisopiston myötävaikutuksella maailmalle.

Aihe tämänkertaisella Ympäristölounaalla oli hyvin aikaan ja paikkaan sopiva: Sinivihreä maisemamme - maa- ja vesiekosysteemien vuorovaikutus. Tilaisuuden armoitettuna juontajana toimi järjestävän säätiön varapuheenjohtaja Sirpa Pietikäinen, joka lupsakkaalla tyylillään nivoi esitykset hyvin yhteen. Varsinaista teemaa lähestyivät omilla havainnollisilla ja asiantuntevilla esityksillään pääjohtaja Lea Kauppi, professori Lauri Arvola sekä stipendiaatti Sari Uusheimo, jonka esitystä referoitiin alustajan sairastumisen vuoksi. Esitykset saivat arvostettua vastakaikua laajassa kuulijakunnassa.

Omalta kohdaltani eniten pohdittavaa ja ajatuksia herättävää oli kuulla vesiensuojelullisten kosteikkojen merkityksestä järvien tilan kohentumisessa. On kustannustehokkaampaa pysäyttää ravinteet pelloille kuin poistaa niitä vesistöistä. Meillä pitää olla taitoa, intoa ja rohkeutta vaikuttaa ympäristön parhaaksi.

Kotiin palatessani pohdin vielä Hämeenlinnan kaupungin tämänvuotista teemavuotta - Luonto ja vesi. Miten osuvasti biologisella asemalla vastattiin tähän huutoon. Toivottavasti saamme mahdollisimman monet huolehtimaan entistä puhtaammista vesistöistämme ja nauttimaan ainutlaatuisesta luonnostamme.

Aarne Kauranen                 

maanantai 14. marraskuuta 2016


Lammin biologisen aseman Ympäristötutkimuksen Säätiö järjesti erikoisnäytöksen Suomen katsotuimmasta dokumenttielokuvasta ”Järven tarina” Hämeenlinnan Verkatehtaan Bio Rexissä 17.8.2016. Säätiön varainkeruutilaisuutena järjestettyyn näytökseen oli kutsuttu käsikirjoittaja/ohjaaja/tuottaja Marko Röhr kertomaan elokuvasta ja vastaamaan katsojien kysymyksiin sen teosta. Moni liki 150 katsojasta kommentoi, että Marko Röhrin kertomukset toivat syvyyttä itse elokuvaan ja olivat oivallinen lisä elokuvanautintoon. Erityisen mielenkiintoisia olivat elokuvan tekemisen aikana ilmenneet monenlaiset vaikeudet ja suuri työmäärä. Yli 700 tunnista materiaalia oli kerätty helmet 76 minuuttiseen dokumenttiin. Paljon loistavaa materiaalia oli kuulemma jäänyt pois. Katsojat saivat kuulla, että parhaita paloja elokuvan ulkopuolelle jääneestä materiaalista tullaan näkemään tulevaisuudessa televisiosta lyhyinä teemapätkinä. Jäämme innolla odottamaan.

Näin kuvasivat elokuvakokemustaan Voglia Oy:n näytökseen kustantamat Lammin lukion abiturientit:

”Järven tarina dokumentti yllätti kaikki positiivisesti sen elokuvamaisuudellaan ja uskomattoman kauniilla kohtauksilla. Dokumentissa oli kaunis musiikki ja ihana iltasatumainen tarina vedenkierrosta. Järven tarinaa katsoessa ei välillä edes uskonut, että se kaikki on kuvattu Suomessa. Sillä se oli niin hienosti kuvattu ja toteutettu puhumattakaan upeista maisemista. Dokumentissa oli saatu kuvattua asioita mitä ei tule todennäköisesti näkemään itse, esimerkiksi mädin kehittyminen ja rupisammakoiden painiminen. Lisäksi dokumentissa oli paljon söpöjä ja hauskoja kohtauksia, kuten majavat, kuutit ja saukon leikki. Dokumentista todella oppi uusia asioita. Kaiken kaikkiaan dokumentti oli loistava ja upea.”

Janne Sundell

Säätiön asiamies

maanantai 12. syyskuuta 2016

Beavers and beetles: studying how a wetland species influences forest beetles

Window traps are emptied out once a
 month so it is important to
attach them firmly to tree trunks. ©Mia Vehkaoja
My PhD research looks at how beavers affect forest beetle populations. I have several research questions: do beaver-induced flood zones have different beetle species assemblages than other areas, do the increased moisture and sunlight conditions in the flood zone affect species assemblage, and do beaver areas advance or hinder potential forest pests or protected species. I have also looked into the dead wood dynamics that beavers create at the flood zones, concluding that beavers are a primary disturbance agent of boreal wetlands. Their actions produce copious amounts of dead wood in boreal forests that are currently highly managed and have consequently become scarce in dead wood, which is necessary for many species of insects, fungi, birds, and even mammals. The dead wood created by beavers is also highly diverse, which therefore maximizes the number of deadwood-dependent species facilitated by beavers. The flooding caused by the species produce e.g. snags and deciduous dead wood, which are especially scarce in the boreal region.

My research combines a game species with widespread effects on its surroundings, and forest beetles, several species of which have become scarce and require protection. Beaver-induced flooding and the species’ habit of felling tree trunks may locally disturb forest owners, but my study is looking into whether beavers’ actions facilitate or disturb forest pests. Combining game and insect research is cool, and generates new information on which to base decision-making for future protection measures, beaver population management, and even for using beavers as a natural tool for restoring degraded wetlands and forests.

Window traps are good for collecting
forest invertebrates. ©Sari Holopainen
Studying insects is interesting yet challenging. Determining individuals to the species level nearly always requires capturing them first, although some species, such as the birch bark beetle (Scolytus ratzeburgi), can be identified by the unique pattern they leave on tree trunks. During the last three years I have used window traps to gather my insect data. The data have been collected from eight sites located at Evo and Isojärvi National Park. Beavers have previously been present at five of the sites, while three sites are controls that are unsuitable for beaver habitation due to certain environmental factors, e.g. not enough deciduous trees. I have a total of 120 traps spread out at the sites, so every summer I collect about 600 samples.

Window traps are widely used for determining the insect assemblages of sites. They are very simple to use: the trap is attached to a tree trunk or set to hang between two trees. Insects crawl or fly into the plastic plexiglas frame and then fall through the funnel into a liquid-filled container at the bottom. The container is filled halfway with water, dishwashing fluid, and salt. The dishwashing fluid prevents the insects from regaining flight, consequently drowning them. The salt helps preserve the insects until the trap is emptied out, which happens about once a month.

After the trap container has been emptied the gathered sample is sifted through using tweezers and a microscope, to separate the insect groups that I am interest in. Next the individuals are determined to the necessary level. Sometimes determining the family level is enough, but if making conservation decisions or gaining new information on certain species is the goal, it is usually necessary to determine individual insects to the species level. How this is done depends on the order in question, e.g. beetles are often recognized by their ankles and genitals. Species, genera, and families are determined using identification keys. The summer of 2016 was the last summer that I collected data for my PhD, so now I can focus on identifying the beetle samples. Once this is complete I can begin statistically analyzing the data. 

University of Helsinki PhD student Stella Thompson is a 2015 LBAYS grant recipient

perjantai 2. syyskuuta 2016

Thermal melanism in the Glanville fritillary butterfly (Melitaea cinxia)

Melanin production in animals has been associated to a number of advantages spanning from UV light protection to a better ability to camouflage or produce warning coloration patterns. The most commonly proposed hypothesis to explain such phenomenon is related to the better ability of darker individuals to absorb and retain heat, and is known as “thermal melanism”. The thermal melanism hypothesis is associated in particular to organisms with a limited ability to thermoregulate, as ectotherms, whose fitness is tightly dependent on climatic conditions. Ectotherms living in cold climates are expected to show a high degree of phenotypic plasticity in order to better adapt to stringent environmental conditions.

In insects, melanin is not only related to the pigmentation of the surface of body parts, but is also released in the hemolymph as a key component of immune response. In fact, when the insect cuticle is breached via wounding or parasitism the phenoloxidase enzymatic pathway is activated and melanin is produced in order to neutralize foreign bodies entering the hemolymph. The activation of insect immunity, and in particular melanin production, has been shown to be a costly process, hence trade-offs between investment in immunity and other fitness-related traits can be expected when the conditions are not optimal.

I wanted to test the thermal melanism hypothesis on the Glanville fritillary butterfly (Melitaea cinxia), for which the northernmost limit of its distribution range is located in the Åland islands. Adults of the Glanville fritillary are observed to fly actively in conditions of full sun and temperatures above 18-20°C. However, when temperatures are lower and the sun is absent they are incapable of moving and performing their activities. In addition, a great variation in the wing pigmentation has been described, hence they are expected to be plastic. To test the plasticity of wings, I have exposed pupae to either a cold or control treatment, took photographs of adult wings and measured their darkness in a series of experiments performed in the spring of 2015 and 2016 at the Lammi biological station.

Furthermore, I was also interested in the connection between melanin allocation to wing patterns and the ability to produce melanin in the hemolymph as a key component of immunity. In order to test this, I collected hemolymph samples of control and previously cold exposed adults and measured the activity of the phenoloxidase enzyme. Finally, to test the costs associated to melanin production I infected control and cold exposed butterflies with a bacterial solution, and assessed lifespan.

Preliminary data show that cold exposed pupae resulted in adults with darker wings, indicating that they are able to modulate melanin allocation to wings in response to thermal conditions. In addition, exposure of pupae to a milder cold treatment still resulted in darker adults, but only in females, which in standard conditions are paler than males. This indicates that wings of the Glanville fritillary are highly plastic, and potentially supports the thermal melanism hypothesis. Contrary to my expectations, the production of phenoloxidase in the hemolymph was higher in adults that had been exposed to the cold conditions, suggesting that there is no trade-off in the allocation of melanin between wing patterns and immune defense. Moreover, the condition of females seemed not to be affected by cold nor bacterial infection, since the lifespan data did not significantly differ among treatment groups. Males showed a similar response, except for the ones that experienced both cold exposure and bacterial infection, for which we observe a significantly lower lifespan. Based on these data, the upregulated phenoloxidase production of cold exposed individuals did not seem to improve the ability to survive or fight infections, but instead it seems associated to a lifespan cost in males.

In order to elucidate the adaptive value of darker butterflies, and demonstrate or reject the thermal melanism hypothesis, I carried out another experiment in a large outdoor enclosure at the Lammi biological station in summer 2016. I measured traits as heat absorption capacity with a thermal image camera, as well as flight ability and reproductive success of cold exposed butterflies to pinpoint potential advantages in terms of dispersal or fitness traits. I am looking forward to the exciting results!

Elena Rosa is a University of Helsinki PhD student and 2015 grant recipient