The number of insects is decreasing in the world. What consequences will this bring? To begin with, plants are taking control of their reproduction or their petals. Flowers evolve to self-pollinate more often. This way they do not depend on increasingly scarce insects that transport their pollen everywhere.
This is the conclusion of researchers from the National Center for Scientific Research (CNRS) and the University of Montpellier (France). They did a genetic analysis of wild pansies (Viola arvensis). They compared them with older ones grown from seeds collected in previous decades.
Plants without nectar
According to the study team, this alteration of 100 million years of evolution can have serious consequences. It can accelerate the decline of insects and make plant populations less diverse. They would be more vulnerable to environmental changes.
“There is a 27% increase in self-fertilization rates carried out in the field during this period,” they write. The flower surface was 10% smaller on average compared to those that bloomed 20 or 30 years ago. Nectar production levels had dropped by 20%. Modern plants receive fewer visits from insects.
It is evident that this feeds off. Fewer insects mean fewer visits from pollinators. The effort and energy the plant puts into producing nectar and making itself attractive is wasted. The plant reduces the size of its petals and nectar production. And insects have even fewer reasons to visit.
Similar processes can be observed in invasive populations that need to adapt new ecological niches. Foxglove populations have evolved to be pollinated by bumblebees in Europe. However, 200 years ago they were introduced to Costa Rica and Colombia. They have since changed the shape of their flowers so that they can be pollinated by hummingbirds.
Dangerous trend
Flowers evolve to self-pollinate, the risk increases. Insects are already threatened by habitat loss and global warming. This now has repercussions on the flowers they pollinate.
«The rapid evolution towards a self-sufficiency syndrome may further accelerate the decline of pollinators. “It is an eco-evolutionary feedback loop with broader implications for natural ecosystems,” they conclude.
