“Our plants and animals are quite robust”
6 May 2019
You cannot be the best at everything. A plant can be visible and very aromatic to attract pollinators or maintain a lower profile to avoid being eaten by herbivores. A new research study published in Science confirms that plants excel at adaptation. This can happen quickly, too.
Jon Ågren, a professor in the Department of Ecology and Genetics, has conducted extensive research on pollination and the ability of plants to adapt to different climates. In the latest issue of Science, he discusses a new study from another research team that has experimented with the wild turnip, investigating how this plant adapts, depending on the circumstances confronting it. The researchers minimised the time bumblebees were released for pollination and subjected the wild turnip to herbivorous insects.
How does a plant attract pollinators?
“For example, a plant can produce aromas or large flowers that can be seen from a long distance. But if a plant exposes itself with aromas and large flowers, it also risks becoming easy prey for herbivores.”
What was the most important thing the researchers concluded in the experiments described in Science?
“That not only pollinators but also herbivores affect how the traits of flowers evolve. The study also shows that this can happen quickly, provided there is genetic variation in the population. After six generations, genetic differences among plants subjected to different treatments already had evolved.”
Plants also seem to have the ability to change genetically in a rather short time to better succeed. In his own research Ågren has studied bird’s-eye primroses growing at Alvaret on Öland. There are bird’s-eye primroses with both long and short stems, and Jon and his colleagues followed the primroses for many years to see what happened to the flowers that grew where there were grazing animals compared with those that grew where no grazing animals were present. In simple terms, the results showed that the primroses with long stems, which make them more visible to pollinators, are more successful where no animals graze and vegetation grows tall, while the primroses with short stems do better in grazed areas.
None of the variations are best in both areas and how well they manage depends on grazing pressure and access to pollinators.
With the climate changes under way, is it good that plants are capable of change?
“Yes, plants have a good potential for adapting. But that requires genetic variation in the population.
“Within a species with many individuals, there are often many different variations in genes, resulting in large genetic variation in the population. If the climate becomes colder, for example, there may be those that are better equipped for that, and if it gets warmer, there are individuals who can tolerate that better. But if all individuals have similar genes, the genetic variation is low, and the population becomes very vulnerable to changes in the habitat.”
The number of pollinators is declining, the climate is changing and humans are using the land in different ways. What should we worry about most?
“We need to understand how these factors affect the ability of plants to survive and reproduce in the long term. Will the plants be able to spread to a more suitable habitat? Do such places exist? Will they have time to genetically adapt to the new conditions? We need to record not only the species that decline, but also what this means for interaction among species. Our plants and animals historically have proven to be quite robust, but what concerns many is the speed at which climate change is happening now.”
Jon Ågren (2019) Pollinators, herbivores, and the evolution of floral traits, Science, DOI: 10.1126/science.aax1656
Published in the Perspective section.