Self-pollinating plant shows rapid loss of genetic variation

An experimental study found that a flowering plant that can self-pollinate lost a lot of genetic variation.

A group of selfing monkeyflower plants lost a significant amount of their genetic variation compared to a group that was born from bumble bees. According to a study published in the journal Evolution, this loss could affect the plants' ability to adapt to environmental challenges. With bee populations on the decline in nature, the findings point to serious issues for wild plants.

In a short amount of time, there were major consequences on the genomes of the plants when they had to selfing.

According to Busch, bees are important to biodiversity in their own right, but the study indicates that their decline will also have devastating impacts on plants.

Plants will lose genetic variation in tens of generations if the pollinators are lost.

Scientists know that self-pollination can endanger a plant's long-term survival, but they don't know how it works or how fast.

Busch's colleagues set up a greenhouse experiment in which a group of plants were isolated from bumble bees. The non-bee plants produced a lot of seeds as they adapted to self pollination. The male and female reproductive parts of the flowers moved closer to each other in order to make it easier to transfer pollen.

The control group that bumble bees visited lost genetic variation compared to the selfing plants.

Busch said that adaptation is key to explain the declines. In selfing populations, a favored genotype will spread if it has an advantage, but it will also spread if it is lucky enough to live in that plant's genome. The phenomenon of "genetic hitch-hiking" is less noticeable when bees visit plants because their offspring are a mix of their parents' genetics.

The consequences of adaptation were changed by strong inbreeding.

Busch said future research should follow plants over a longer period of time to see if the loss of genetic variation causes population collapse.

To know how quickly highly inbred groups will go extinct is the next step. The consequences of pollinator loss need to be understood by us. It will affect wild populations of plants. Many crops depend on bees.

More information: Jeremiah W. Busch et al, Pollinator loss causes rapid adaptive evolution of selfing and dramatically reduces genome‐wide genetic variability, Evolution (2022). DOI: 10.1111/evo.14572 Journal information: Evolution