PhD, Docent, Academy Research Fellow
Bioeconomy Research Team
Functional Ecology and Applications Team (FEAT)
Evolution and maintenance of colour polymorphism in natural populations
Ecological immunology - interactions between host physiology and disease ecology
Predator - prey interactions
Life history evolution
Ecological economics in forestry and agriculture
Societal impacts of the state of the environment and its management
I am an evolutionary ecologist with my main research interests ranging from ecological immunology to life history evolution, behavioural ecology and population dynamics. In my research I investigate ecological and evolutionary processes acting under environmental change in order to understand and predict the persistence of species. I use individual based long-term data and detailed experiments in specific model systems to get new insights in such processes. I believe high quality basic research built around a solid theoretical framework is the key to successful applications in nature conservation and natural resource management.
I did my MSc and PhD in ecology and evolutionary biology at the University of Helsinki. As a post doc I have worked in the University of Helsinki, Lund University (Sweden) and Åbo Akademi University with funding from the Foundations Post doc pool and the Academy of Finland. I started at Novia UAS as a senior researcher in late 2015.
Currently (9/2017-8/2022) I am working as an Academy research Fellow funded by the Academy of Finland at Novia UAS with the project "Spatio-temporal eco-evolutionary dynamics under environmental change" (ECCHO_owl). In this project we study adaptations to environmental change using the tawny owl study system. One of few examples of climate-driven natural selection and population-level microevolutionary change is based on the study object in this project – the tawny owl (see ref below, Karell et al. 2011 Nat Commun). Tawny owls appear in grey and brown highly heritable colour morphs, of which the grey has higher survival in cold and snow-rich winter conditions. In mild winters there is no survival difference between the morphs. The emphasis in the Academy fellowship project is to 1) understand the underlying ecophysiological selection mechanisms by which the grey performs better than the brown morph in cold and snow-rich winters, 2) to investigate selection pressures and adaptation in other populations living in different environmental conditions, 3) statistically model how environment-driven selection and demography contribute to the observed genetic changes in the population and 4) explore the latitudinal clines and geographic patterns of colour polymorphism that are expected to originate from climate driven selection on colouration.
Recently I have also become interested in more applied questions dealing with interactions between biodiversity, natural resource use and ecosystem services in forestry and agricultural landscapes. I am also interested in societal impacts of the environment and development of evidence based sustainable management tools. In these interdisciplinary projects we combine expertise from evolutionary biology, political science, marine ecology, conservation biology, engineering and agroecology.
The FEAT and their projects
MSc Katja Koskenpato, Phd-student (University of Helsinki and Novia UAS): Ecological energetics under climate change: a case study of the colour polymorphic tawny owl
PhD Chiara Morosinotto, post doc: Ecophysiological adaptations in the colour polymorphic tawny owl
MSc Ruslan Gunko, PhD-student (University of Helsinki and Novia UAS): State of the environment as a corner stone of societal life quality: a local scale approach (together with Lauri Rapeli and Matias Scheinin).
BSc Kia Kohonen, MSc-student (University of Helsinki): Prey choice under variable food conditions in the colour polymorphic tawny owl
BSc Martti Kujansuu, MSc-student (Novia UAS): The Utilisation of Geographic Information Systems in Finnish Municipalital Environmental Administration
Lund University, Sweden: Staffan Bensch, Jan-Åke Nilsson, Johan Nilsson
University of Lausanne, Switzerland: Alexandre Roulin
University of Turku: Jon Brommer
University of Helsinki: Aleksi Lehikoinen, Jari Valkama, Hannu Pietiäinen
Åbo Akademi University: Markus Öst, Lauri Rapeli
Peer reviewed publications
Öst, M., Lindén, A., Karell, P., Ramula, S. & Kilpi, M. 2018. To breed or not to breed: drivers of intermittent breeding in a seabird under increasing predation risk and male bias. — Oecologia. https://doi.org/10.1007/s00442-018-4176-5.
Ramula, S., Öst, M., Lindén, A., Karell, P. & Kilpi, M. 2018. Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders . — PLoS ONE 13(4): e0195415. https://doi.org/10.1371/journal.pone.0195415
Karell, P., Bensch, S., Ahola, K. & Asghar, M. 2017. Pale and dark morphs of tawny owls show different patterns of telomere dynamics in relation to disease status. — Proceedings of the Royal Society of London B, 284: 20171127.
Sæther, B-E., Grøtan, V., Engen, S., Coulson, T., Grant, P., Visser, M.E., Brommer, J.E., Grant, R., Gustafsson, L., Hatchwell, B.J., Jerstad, K., Karell, P., Pietiäinen, H., Roulin, A., Røstad, O.W., Weimerskirch, H. 2016. Demographic routes to variability and regulation in bird populations. — Nature Communications, 7: 12001 doi: 10.1038/ncomms12001
Koskenpato, K., Ahola, K., Karstinen, T. & Karell, P. 2016. Is the denser contour feather structure in pale grey than in pheomelanic brown tawny owls Strix aluco an adaptation to cold environments? — Journal of Avian Biology, 47: 1-6.
Öst, M., Ramula, S., Lindén, A., Karell, P. & Kilpi, M. 2016. Small-scale spatial and temporal variation in the demographic processes underlying he large-scale decline of eiders in the Baltic Sea. — Population Ecology, 58: 121–133.
Brommer, J.E., Karell, P., Aaltonen, E., Ahola, K. & Karstinen, T. 2015. Dissecting direct and indirect parental effects on reproduction in a wild bird of prey: Dad affects when but not how much. — Behavioural Ecology and Sociobiology, 69: 293–302.
Brommer, J.E., Karell, P., Ahola, K. & Karstinen, T. 2014. Residual correlations, and not intrinsic properties of the individuals, determine a nest defense boldness syndrome in tawny owls. — Behavioral Ecology, 25: 802–812.
Karell, P., Brommer, J.E., Ahola, K. & Karstinen, T. 2013. Brown tawny owls moult more flight feathers than grey ones. — Journal of Avian Biology, 44: 235–244.
Pavon-Jordan, D., Karell, P., Ahola, K., Kolunen, H., Pietiäinen, H., Karstinen, T. & Brommer, J.E. 2013. Environmental correlates of annual survival differ between two ecologically similar and closely related owl species. — Ibis, 155: 823-834.
Ekroos, J., Öst, M., Karell, P., Jaatinen, K. & Kilpi, M. 2012. Philopatry predisposes to predation-induced ecological traps: habitat-dependent mortality of breeding eiders. — Oecologia, 170: 979–986
Karell, P., Ahola, K., Karstinen, T., Kolunen, H., Siitari, H. & Brommer, J.E. 2011. Blood parasites mediate morph-specific maintenance costs in a colour polymorphic wild bird. — Journal of Evolutionary Biology, 24: 1783-92.
Karell, P., Ahola, K., Karstinen, T., Valkama, J. & Brommer, J.E. 2011. Climate change drives microevolution in a wild bird. — Nature Communications, 2: 208 / ncomms1213.
Karell, P., Lehtosalo, N., Pietiäinen, H. & Brommer, J.E. 2010. Ural owl predation on field and bank voles by size, sex and reproductive state. — Annales Zoologici Fennici, 47: 90-98.
Kontiainen P., Pietiäinen, H., Karell, P., Pihlaja, T. & Brommer, J.E. 2010. Hatching asynchrony is an individual property of female Ural owls which improves nestling survival. — Behavioral Ecology, 21: 722-729.
Brommer, J.E., Pietiäinen, H., Ahola, K., Karell, P., Karstinen, T. & Kolunen, H. 2010. The return of the vole cycle in southern Finland refutes the generality of the loss of cycles through "climatic forcing". — Global Change Biology, 78: 577-586.
Karell, P., Ahola, K., Karstinen, T., Zolei, A. & Brommer, J.E. 2009. Population dynamics in a cyclic environment: Consequences of cyclic food abundance on tawny owl reproduction and survival. — Journal of Animal Ecology, 78: 150-162
Karell, P., Pietiäinen, H., Siitari, H., Pihlaja, T., Kontiainen, P. & Brommer, J.E. 2009. Parental allocation of additional food to own health and offspring growth in a variable environment. — Canadian Journal of Zoology 87: 8-19.
Kontiainen, P., Pietiäinen, H., Huttunen, K., Karell, P., Kolunen, H., Brommer, J.E. 2009. Aggressive Ural owl mothers recruit more offspring. — Behavioral Ecology, 20: 789-796.
Karell, P., Kontiainen, P., Pietiäinen, H., Siitari, H. & Brommer, J.E. 2008. Maternal effects on offspring Igs and eggsize in relation to natural and experimentally improved food conditions. — Functional Ecology 22: 682-690.
Kontiainen, P., Brommer, J. E., Karell, P. & Pietiäinen, H. 2008. Heritability, plasticity and canalization of Ural owl egg size in a cyclic environment. — Journal of Evolutionary Biology 21: 88-96.
Kekkonen, J., Kolunen, H., Pietiäinen, H., Karell, P. & Brommer, J. E. 2008. Tawny owl reproduction and offspring sex ratios under variable food conditions. — Journal of Ornithology 149: 59-66.
Karell, P., Pietiäinen, H., Siitari, H. & Brommer, J. E. 2007. A possible link between parasite defence and residual reproduction. — Journal of Evolutionary Biology 20: 2248-2252.
Brommer, J.E., Karell, P. & Pietiäinen, H. 2004. Supplementary fed Ural owls increase their reproductive output with a one year time lag. — Oecologia 139: 354-358.
Brommer, J. E., Karell, P., Pihlaja, T., Painter, J., Primmer, C. & Pietiäinen, H. 2003. Ural owl sex allocation and parental investment under poor food conditions. — Oecologia. 137: 140-147.