Nature and nurture both important

How do genes and environment interact? In recent years research has shown that offspring can be affected by what their parents have experienced. Tobias Uller is studying great tits and water fleas to understand why.

Tobias Uller

Researcher at the Department of Biology

Wallenberg Academy Fellow 2012

Lund University

Research field:
Evolutionary ecology, epigenetics

Researchers were long in agreement: characteristics are inherited via genes passed on by parents to their offspring. New characteristics may arise as genes change at random. Which genes become most common is determined by natural selection; the individuals best adapted to their environment have a better chance of reproducing and passing their genes on. But it is not quite that simple.

“An organism reacts to its environment, and not only randomly. Evolution occurs more rapidly and less randomly than can be explained by the classical approach. This is clear, but has nonetheless been surprisingly difficult to get people to accept,” Tobias explains.

In an attempt to explain how changes in a population can rapidly take a certain direction, he draws a quick sketch on a whiteboard. He likes drawing, he says. What he does not like doing is spending too long on the same thing.

“I am a restless spirit when it comes to research. I easily get bored. I am most interested in the big picture.”

“It is a great honor that my research was considered sufficiently interesting for me to be admitted as a Wallenberg Academy Fellow. For me it’s about creating unconventional research environments. I am impressed and delighted with the Foundation’s vision as I perceive it: if we focus on researchers considered by their colleagues to be doing something important, the result will be useful research. It is exciting to be able to make a contribution.”

“Black” biology turned green-white

After high school Tobias knew what he wanted to do: one year of math at university, one year of biology – then he would choose the one he thought was most fun. Be he started to read about evolution when he was still studying math. He realized that was what he wanted to do.

Biologists are often described as “green” and “white” – those working in the field of nature and those working at molecular level. Tobias called his kind of biology “black” – he was most interested in conceptual problems.

“I am addicted to learning; I have to learn new things all the time. And I want to understand interrelationships on a theoretical plane.

In time Tobias became a green biologist in any case, perhaps with a few white stripes. In Australia and Europe he has researched on heredity and evolution in frogs and lizards. More recently he has begun examining “epigenetic factors”. These are molecules attached to the DNA chain and to the molecules around which DNA wraps. They control which genes become active and which do not.

Epigenetics more malleable than genes

The DNA sequence cannot be affected by what an organism experiences, but epigenetic factors can. Molecules are connected up and disconnected during the course of life. In one well-known study it was shown that Dutch women who became pregnant during a period of famine at the end of the Second World War gave birth to children who ran a higher risk of cardiovascular and other diseases later in life. The explanation lay in epigenetic changes occurring in the children, controlling their genes and hence their health later on.

Some epigenetic factors can also be inherited. This means that the environment of an individual can in fact affect its offspring.

“Epigenetic factors in plants can be inherited for 15 – 20 generations, and the factors are much more sensitive to environmental variations than DNA is,” Tobias says.

But epigenetic factors in mammals are deleted when fertilization takes place. There is no evidence that we inherit them in the same way as plants do. Yet there are studies that suggest inheritance may occur in some cases.

Great tits and water fleas

Along with the grant from the Knut and Alice Wallenberg Foundation, Tobias was offered a post at Lund University. He worked there seven days a month in 2014. The remainder of his time was spent at Oxford University in Great Britain. As of 2015 he works full-time in Lund. Birds (the European great tit – Parus major) and water fleas are the focal point of his research. He and his team are studying tit chicks and taking blood samples from them before they leave the nest. The samples are used to compare epigenetic factors in individual chicks. The aim is to see how epigenetics are affected by early life, e.g. clutch size, availability of nutrition, nest site and parental behavior.

Tobias is not only studying water fleas; he is trying to influence them. He wants to see how their appearance and behavior change when their environment changes and stresses them.

“We have a pretty good idea how water fleas are affected by metals, and how they cope with them, so my idea is to use metal contaminants in the water. The aim is to mimic the situation when a population experiences a new habitat in the wild. These experiments will enable us to understand how new adaptations originate and evolve.”

Text Lisa Kirsebom
Translation Maxwell Arding
Photo Magnus Bergström