Although scientists knew that self-pollination could threaten the long-term survival of plant species, they did not understand the mechanism behind this threat and how quickly it became detrimental. To figure this out, a team of researchers led by Jeremiah Bush of the University of Washington conducted a genetic study.
“We found that in a very short period of time, the genomes of plants had serious consequences when they had to switch to self-pollination,” Bush said.
The team compared a group of self-pollinating monkey flowers to a group of monkey flowers pollinated by bumblebees. They determined that “self-pollinating” plants lost between 13 and 24 percent of their genetic variation, with significant loss occurring within nine generations.
We already know that genetic variation is a major factor in determining how species adapt to changing environmental conditions, so this loss can seriously interfere with a plant’s ability to survive.
Bush explained that in self-fertilizing populations, certain genotypes could be selected if they were found to be favorable. However, some harmful mutations can also “hitchhike”. Such “genetic hitchhiking” is less likely in populations pollinated by bees due to mixing of genetic material.
“Strong inbreeding has fundamentally changed the effects of adaptation,” Bush explained. The results are particularly tragic given the global bee decline.
“If pollinators disappear, it will be a problem not only for them: plant populations will lose genetic diversity in tens of generations – not thousands, but tens.”
Bush would be interested in seeing long-term studies to determine if and when population collapse due to lack of pollinators and loss of genetic diversity occurs.
“The really important next step is to find out how quickly the viability of highly inbred groups will decline over time – to understand how quickly these populations will become extinct,” Bush said. “We need to really understand what the consequences of pollinator loss are. It will make a difference for wild plant populations and crops. A lot of crops depend on bees.”
This study can be found in the journal Evolution.