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According to scientists, flowers are adapting to a scarcity of insects by evolving to self-pollinate.

Researchers have stated that flowers are adapting to the decline in insect populations by becoming less appealing to pollinators.

A recent research has discovered that field pansies in the vicinity of Paris have decreased in size by 10% and their nectar production has decreased by 20% compared to those found in the same fields 20-30 years ago. Furthermore, they are receiving fewer visits from insects.

According to Pierre-Olivier Cheptou, a researcher at the French National Centre for Scientific Research and one of the study’s authors, our research has revealed that pansies are undergoing an evolutionary process in which they are relinquishing their reliance on pollinators. They are shifting towards self-pollination, where each individual plant reproduces with itself. While this may be effective in the short term, it could potentially hinder their ability to adapt to forthcoming changes in their environment.

Plants produce nectar for insects, and in return insects transport pollen between plants. This mutually beneficial relationship has formed over millions of years of coevolution. But pansies and pollinators may now be stuck in a vicious cycle: plants are producing less nectar and this means there will be less food available to insects, which will in turn accelerate declines.

According to Samson Acoca-Pidolle, a doctoral researcher at the University of Montpellier, our findings reveal a rapid decline in the historical connections between pansies and their pollinators. The rate at which these plants are evolving is unexpected.

Research in Europe has documented a decrease in insect populations. A study of nature reserves in Germany revealed that between 1989 and 2016, the combined weight of insects caught in traps decreased by 75%. Acoca-Pidolle stated that this decline has also affected pollinators and that it will be difficult to reverse the consequences, as plants have already begun to adapt. It is crucial to implement conservation efforts in order to stop and reverse this decline in pollinators.

The technique utilized in the research is referred to as “resurrection ecology”. It entailed sprouting original pansy specimens from seeds gathered in the 1990s and 2000s, which were being preserved in national botanical conservatories. The group analyzed the changes that occurred in four populations of field pansies (Viola arvensis) during this time frame.

According to the publication in the New Phytologist journal, there were no differences observed in the populations besides alterations in the flowers. This includes factors such as leaf size and overall plant size.

If insects are not attracted to flowers, then a plant is expending energy by producing large and nectar-rich flowers. Studies have revealed that the proportion of field pansies that rely on self-pollination has risen by 25% in the last two decades.

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Dr. Philip Donkersley, a researcher from Lancaster University who was not part of the study, stated that this is an especially thrilling discovery because it demonstrates evolution occurring in the present moment.

It is surprising that these flowers are altering their approach due to a decline in pollinator numbers. This study demonstrates a plant reversing its evolutionary process in reaction to a relatively new occurrence.

“Despite the majority of research being conducted in Europe and North America, it is evident that the decline of pollinators is a worldwide issue. These findings may only represent a small portion of the problem: regions with higher levels of plant diversity are expected to have a greater number of wild plants altering their pollination methods due to the scarcity of pollinators.”

A humming bird with its beak in a foxglove flower

Similar processes can be seen in invasive populations that need to adapt new ecological niches. Populations of foxglove have evolved to be pollinated by bumblebees in Europe. However, 200 years ago they were introduced to Costa Rica and Colombia, and they have since changed the shape of their flowers so they can be pollinated by hummingbirds, researchers found.

Additional studies demonstrate that plants lacking the ability to self-pollinate exhibit a different strategy, where they increase their pollen production in response to limited pollinator availability. Since they do not have alternative means of pollination, these plants must compete with other species in order to attract a dwindling population of pollinators.

Professor Phil Stevenson from the Royal Botanic Gardens, Kew, who was not involved in the study, pointed out that it is logical for characteristics that attract and benefit pollinators to alter in response to a decrease in their numbers. This is particularly true for species that have the ability to self-pollinate.

According to him, this is particularly true for the process of reproduction, which is arguably the most crucial function of living organisms and possibly the most advantageous characteristic of all.

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Source: theguardian.com