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10/02/2024 | Press release | Distributed by Public on 10/01/2024 21:09

An international career in studying adaptation of natural populations led to a professorship at the University of Jyväskylä

An international career in studying adaptation of natural populations led to a professorship at the University of Jyväskylä

Katja Räsänen, a new professor at the University of Jyväskylä, studies how the Finnish water lice and the threespined stickleback populations of Lake Mývatn in Iceland adapt to changing environments. Räsänen has built international networks and accrued experience around the world. She started as a professor of evolutionary and environmental biology in the Department of Biological and Environmental Science at JYU on 1 September 2024.
Katja Räsänen started as a professor of evolutionary and environmental biology in the Department of Biological and Environmental Science at JYU on 1 September 2024.
Published
2.10.2024

Professor of Evolutionary and Environmental Biology Katja Räsänen is an evolutionary ecologist with interest in processes that maintain and alter biological diversity. She especially wants to understand holistically the dynamic interactions between wild organisms and their environment, from the molecular level to the level of individuals and ecosystems. Her research focuses on how organisms adapt to environments that change naturally or because of anthropogenic activity, and the feedbacksbetween evolutionary and ecological factors. The research in her team is done in the field and the laboratory as well as in the office.

"Ecology and evolutionary biology offer excellent opportunities to reflect on the origin of life and its diversification both in the moment in which we live and over millions of years," says Räsänen.

Research on the water louse in changing environments

Water lice (Asellus aquaticus), freshwater isopods,haveproved to be especially interesting research organisms. Isopods are an order of invertebrates with 10,000 species that belong to malacostracans. Globally, there are about 500 different species of water lice living in freshwater environments, but in Finland only Asellus aquaticus. Freshwater water lice play an important role in ecosystems, as they are decomposers that feed mainly on microbial and plant matter. Räsänen's research team focuses on the impacts of chemical contaminants on water lice.

"My own target of interest is the host-microbiome interaction of water lice," Räsänen says. "I want to understand, for example, how the gut microbiome influences water lice and especially how water lice can live in a broad range of different environments."

Water lice are an ideal research species because they are easy to breed in the laboratory, and conduct controlled experiments, such as exposing to different chemicals in the lab as well as in ecologically relevant experimental settings in mesocosms.

"In Finland, we have also studied the indirect impacts of chemicals on water lice by exposing leaf litter to fungicides," Räsänen explains. "We noticed that when water lice ate the leaf litter exposed to fungicides, it affected their growth, pigmentation and behaviour."

Three-spined sticklebacks provide insight to the evolution of natural populations

Research in Räsänen´s team is also conducted outside Finland. During her years abroad, Räsänen became familiar with the three-spined stickleback (Gasterosteusaculeatus) and has continued to study it also since starting at the University of Jyväskylä. The three-spined stickleback is a small, less than 10 cm long fish. It is commonly found in the oceans and freshwaters of the northern hemisphere and has increased in abundanceinthe western Baltic Sea from Ålandto Denmark.

With the help of the three-spined stickleback living in Lake Mývatn, in Iceland, Räsänen investigates how spatial and temporal variation of the environment affects the phenotype and genetic variation of the fish.

"Together with our Icelandic colleagues, we study evolutionary changes inthemorphology of the fish in relation to, for example, the local temperature differences of Mývatnor the temporal changes in non-biting midges that the three-spined sticklebacks feed on," Räsänen says. "Using genetic methods and time-series datasets, we have found, among other things, evidence for genetic changes of traits related to diet of three-spined sticklebacks."

Studies on freshwater organisms are important because freshwater ecosystems are the lifeblood of biodiversity, as well as human well-being. Drastic habitat changes can also break up populations into smaller units that may not be able to adapt to rapidly changing environments.

Extensive international networks

Räsänen has always been interested in the behaviour of animals. After graduating from upper secondary school, she planned to become a veterinarian but felt that her skills in physics and chemistry were not strong enough. However, she noticed that it is also possible to learn about animal behaviour by studying biology, so she started her biology studies at the University of Oulu in 1990. During her master's degree studies, she ended up writing her master's thesis about the behavioural ecology of birds at Uppsala University, in Sweden, which also led to doctoral studies there. Her PhD dissertation focused on how moor frogs (Rana arvalis) have adapted to human induced acidification of the environment. Räsänen completed her doctorate at Uppsala University in 2002.

As a postdoctoral researcher, Räsänen's journey continued to McGill University in Montreal, Canada. In Canada she got to know the three-spined stickleback for the first time as she studied their ecological speciation. After two and a half years, she headed to Switzerland in 2006. Until 2008, she worked there as a junior researcher at ETH-Zürich and Eawag(Swiss Federal Institute of Aquatic Science and Technology) and after that as a tenured senior researcher at Eawag. At Eawag, she continued her research on moor frogs and started investigations on water lice as well as the Icelandic three-spined stickleback. In all of these projects her team studied ecological and evolutionary responses to changing environments.

JYU.Wisdomattracts to Jyväskylä

After a long international career, Räsänen wanted to return closer to home and looked for positions in the Nordic region. She noticed a tenure track position on evolutionary ecology and environmental sciences at the University of Jyväskylä and decided to apply for it.

"I had never visited Jyväskylä, excluding the railway station," Räsänen says. "What's more, I was interviewed online because of the Covid-19 pandemic. However, I have not regretted moving to Jyväskylä because the multidisciplinary approach of the University and the closeness to nature have made me feel at home."

JYU.Wisdom, the School of Resource Wisdom, was also one of the reasons to apply for Jyväskylä. Räsänen is part of the JYU.Wisdomnetwork.

"I had heard about the JYU.Wisdomnetwork already before I applied for the position at the University of Jyväskylä," she says. "The network's multidisciplinary approach and visibility, as well as the whole concept were very interesting. JYU.Wisdomhas brought me new ideas for my work, especially when it comes to societal interaction."

Science is a way to seek new knowledge

For Räsänen, the most important thing in her work is science and the ability to reflect and understand how processes in nature work.

"Science is a way to try to understand how things really are, how nature functions, and what impacts the human-environment interaction has at large," she says. "Research leads to a better understanding of the world."

Even though the daily work is often done alone, the sense of community at the University of Jyväskylä has helped in her work.

"I no longer have the time to do field work as often as I would like to," she says. "However, it is wonderful to discuss and exchange ideas with good colleagues in difficult moments, and one´s own team is an important part of a researcher's daily life. Not to mention that you can also get new ideas when walking your dog in the woods!"

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