The art of solving ecological life puzzles
Why are certain insects only interested in a certain type of plant and not others? And what do plants do to attract just one type of insect? Understanding the intricate interplay between plants and insects is the goal of ecologist Magne Friberg.
The scent of Californian woodland stars in full bloom fills the greenhouse at the Evolutionary Biology Centre. At first glance, the thousands of small white flowers look identical, but on closer inspection a number of differences emerge. Some have overlapping petals. In others, the petals are spaced widely apart. And yet they belong to the same species.
“This variation of course exists between different populations, but we also see great variation between individuals of the same species growing in the same place,” says Magne Friberg at the Department of Ecology and Genetics. “Why that is so, we’re not sure. It’s really interesting.”
Another difference is the scent. The Californian plant species (Lithophragma bolanderi in Latin) has the highest within-species floral scent variation of any species measured. Some individuals are dominated by substances that make them smell like old-fashioned Jenka chewing gum. Other variants secrete an aromatic ether that has other associations for Magne Friberg.
“I’m almost certain that this scent was in the perfume my secondary school headmistress wore,” he says. “You could smell it when she’d walked through the hallway. You had to take care not to do anything stupid because you knew the headmistress was nearby,” he says and laughs.
Yet there are also variations within the California population that emit scents largely imperceptible to humans, but which the researchers can detect with the help of a gas chromatograph. This instrument separates the scent’s chemical compounds and sends them to a mass spectrometer for further analysis. The substantial scent variations are one of the puzzles Magne Friberg’s research team wants to solve. Does the answer lie in differences in the number of chromosomes? Or in the various insects that visit the plants?
“We know that the moth Greya politella is a very important pollinator of woodland star plants, but we don’t know how important other pollinators are, such as bees and flies flying between many different flowers,” says Magne Friberg.
“Cross-fertilised plants need to get pollen from other individuals in order to produce seeds. But the problem is that each signal a flower sends out to a friend can also be detected by an enemy. This is a difficult evolutionary problem for the plants.”
To get to the root of the question of how different scents develop or are encouraged by selection, the research team grows individual plants that are then combined in traditional genetic test-cross charts. In this way, the researchers hope to find out how scent secretion is inherited. The question remains, however, why so many varied scents are even permitted to occur.
“Imagine a plant population that is very dependent on a particular type of insect pollinator,” says Magne Friberg. “The insect can detect a certain number of scents. The plants that stay within the range of scents that the insects can detect should be totally fine. But if one starts to emit scents that are so different they are no longer recognised, it should be selected against. Instead, we see this amazing scent variation that we are now trying to understand.”
Magne Friberg stumbled into his research domain by chance during his post-doctoral studies at the University of California, Santa Cruz in the US. There, he studied a specific pollinator system in which butterflies lay eggs in a flower while they are pollinating it, thereby becoming both enemy and friend in different life stages. Today, he is researching what it is that makes some female insects want to lay eggs in certain plants and not in others, and how this affects both the plant and the insects.
Magne Friberg points to a map of the western United States on his screen, covered with circles of different colours. Each circle represents different combinations of interaction patterns between plant and insect species.
“Every time I travel to a new valley in the Sierra Nevada, take a scent sample and return to the lab in Santa Cruz, I get to see something new that no one else has ever seen before,” says Magne Friberg. “This is really exploratory research. It’s taken us almost seven years to get to a point where we are ready to publish our findings, because we’ve been sitting and looking at the California map – and I’m still sitting here! – and wondering ‘what happened here, and in this area, and this one?’,” says Magne Friberg with a laugh.
It all seems like an extremely complex puzzle of life, virtually impossible to even grasp, let alone draw any conclusions about. But the development of new technology has made it somewhat easier to answer new questions, says Magne Friberg, because there are now greater opportunities to take large-scale scent samples and conduct quantitative analyses of scent variations within and between species.
“We have an amazing infrastructure in Uppsala,” says Magne Friberg, “with the ability to grow plants in the right lighting and temperature environments and conduct behavioural experiments in which insects encounter different plants from different environments. This gives us a chance to identify characteristics that differ among populations and that seem important for the interaction between different organisms.”
Magne Friberg leads two courses, one in ecological methods in the spring and one survey course on human environment in the autumn. Something he really wants to convey to the students is the insight that there may not be any correct answers.
“One thing I’ve thought a lot about concerning my research is that I am pretty good at knowing what I don’t know,” he says. “And it has to be okay even for teachers to not know things. Some things we have to learn together. It is when we test different theses and understand what we can explain and not explain that we suddenly find our next research project.”
ABOUT MAGNE FRIBERG
Title: Postdoctoral research fellow and Docent of Biology at the Department of Ecology and Genetics.
Family: Wife and two daughters.
In his free time: Handball coach for 23 twenty-year-old women in Uppsala HK.
Would like to do more of: Birdwatching, exercise (especially tennis or squash).
Strengths: Persevering, kind.
Weaknesses: Worrier (don’t like the uncertainty in the life of a researcher), time optimist.
Wanted to be when I was little: Handball pro, rock star, researcher (I tried the first two first, but failed).