French wild pansies are producing smaller flowers and less nectar than twenty to thirty years ago, study shows

From the article:

A study has found the flowers of field pansies growing near Paris are 10% smaller and produce 20% less nectar than flowers growing in the same fields 20 to 30 years ago. They are also less frequently visited by insects.

“Our study shows that pansies are evolving to give up on their pollinators,” said Pierre-Olivier Cheptou, one of the study’s authors and a researcher at the French National Centre for Scientific Research. “They are evolving towards self-pollination, where each plant reproduces with itself, which works in the short term but may well limit their capacity to adapt to future environmental changes.”

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The method used in the study is called “resurrection ecology”. It involved germinating ancestral pansy plants from seeds collected in the 1990s and 2000s, which were being stored in the national botanical conservatories. The team compared how four populations of field pansies (Viola arvensis) had changed during this period.

Other than changes to the flowers, they found no other changes between the populations, such as the leaf size or total size of the plant, according to the paper, published in the journal New Phytologist.

If flowers are not likely to attract insects, then a plant is wasting energy making them large and nectar-rich. Previous research has shown the percentage of field pansies relying on self-pollination has increased by 25% over the past 20 years.