2023-12-20 17:11:32
But what is “truly innovative is that we show in a natural environment an evolution of plants towards a break in their interaction with pollinators over the last 30 years”, continues this first author of the study published in New Phytologist.
Smaller flowers also have less nectar
The team from the Center for Functional and Evolutionary Ecology, the CEFE, looked into the fate of field thinking (Viola arvensis) and its pollinators, on four sites in the Paris region. It relied on a technique of “resurrection ecology”, which consists of comparing contemporary flowers to those whose seeds were collected on the same sites more than 20 years ago and kept in national botanical conservatories. .
Result: in this Paris region where the decline in the number of pollinators is marked, current flowers are 10% smaller and produce 20% less nectar than their close ancestors. Nothing surprising, since “the moment the nectar is no longer useful, if there are no more pollinators, there is no point in producing it because it is just a cost for the plant,” explains Pierre-Olivier Cheptou, CNRS research director at CEFE and co-author of the study.
An “evolving cul-de-sac”
The decline of flying insects is documented in many parts of Europe, due to intensive agriculture, pollution and climate change. The CEFE study indicates that this decline affects in record time a co-evolution of several million years with flowering plants. For the wild thoughts of study do not merely economize one’s strength. They redirect them towards self-fertilization, a phenomenon in which “each plant reproduces with itself”, continues Pierre-Olivier Cheptou.
Also read: Saved from extinction: There are no more flowers for wild bees!
Some 80% of flowering plants have this capacity and “a large part” could therefore “evolve towards self-fertilization” in the absence of pollinators, continues Samson Acoca-Pidolle. Which would be far from being a panacea. Firstly because the process would represent an “evolutionary dead end, quite irreversible”, according to Pierre-Olivier Cheptou, since with a very homogeneous genetic heritage, “you have fewer possibilities of adaptation”.
The second consequence is more immediate and should affect crops. Wild pansies are messicole plants, that is to say present in agricultural crops, such as rapeseed or sunflower. By attracting pollinators, they promote their pollination.
Bees and bumblebees, the first victims
The big loser remains the pollinator, the victim of a real vicious circle. Its decline pushes plants to produce less nectar and therefore make its food source scarce, which further threatens its survival and causes plants to do without it.
Read finally: In Switzerland, the discreet upheaval of insect populations
The phenomenon also has serious consequences for certain flowering plants in meadows containing several species. According to Pierre-Olivier Cheptou, researchers have observed a “rareness of plants that are pollinated by insects, in favor of species that are more self-fertilizing.”
The results are “quite worrying”, for Samson Acoca-Pidolle. Who asks: “Can we return to the previous state by stopping putting pressure on pollinators, or is this interaction with flowers lost forever?”
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