By Kathleen Berger, Executive Producer for Science & Technology
Plants that rely on bees or other insect pollinators to transport pollen between like individuals — buzzing from violet to violet, for example — face uncertainties when spring and summer become front-loaded. Suddenly bees have a lot more flower options at the same time earlier in the season.
“I have noticed this year markedly earlier flowering in a lot of species, which I think is likely due to the warmer winter we had,” said Matthew Austin, an ecologist and biodiversity postdoctoral fellow with the Living Earth Collaborative at Washington University in St. Louis.
A key question on researchers’ minds remains: How will this competitive atmosphere affect plants? Austin is on a mission at Shaw Nature Reserve, an extension of Missouri Botanical Garden in Gray Summit.
“The project that I’m working on is looking at the ecological and evolutionary implications on pollination systems as a result of a change in climate,” he explained. “We know that climate change has altered the time of year that plants flower in certain places, including the greater St. Louis area. We see that a warming climate is not only causing flowers to bloom earlier, but in many species, it’s also causing flowering to end later.”
Austin said earlier blooms and a longer flowering season would be confusing to bees. Suddenly, there are a lot more flowering options at one time.
“Flowers might have shifted earlier, while the time of year that bees are active has stayed the same.”
And if bees are confused and things don’t happen the way they’re supposed to, the beauty and survival of flowers eventually suffer. And the survival of bees would become a concern.
“The time of year that bees are out, they could be left without the flowers that they normally feed from,” said Austin. “While research is ongoing on bee populations, if bees are not able to feed from flowers that they have historically in the past, if they’re not able to shift to feeding on a different species, you could see declines of their populations.”
This would be a most undesirable outcome, as many humans rely on bees for certain foods.
“Many of our fruits and vegetables, tomatoes, blueberries, strawberries, a lot of these just delicious foods that people love to eat,” Austin described. “And can also just affect how likely we are to see the flowers that we enjoy in our native environment. So, my research is exploring what effects these altered flowering times and greater number of species flowering at the same time have caused for pollination and floral evolution.”
To determine potential outcomes, Austin will examine the survival of flowers native to Missouri. He reviewed historical records of flowering times collected along a stretch of path at Shaw Nature Reserve dating back to the 1930s, to early 40s. According to the data, most of the species at Shaw are flowering at a different time now than they used to about 80 years ago.
Then conducting his own pollination study, Austin chose the flower Jacob’s Ladder.
“To conduct my hand-pollination experiments, I’m doing the work that a bee would do. However, to be very careful and controlled in my experimentation, I have to make sure that other bees or other pollinators aren’t also pollinating the flowers that I’m working with,” he explained.
With climate change and many different flowers in bloom at the same time, cross-pollination by confused busy bees is more likely.
“The question that my hand-pollination experiments are testing is whether – if a flower receives pollen from a different species, it will be a reproductive dead end. Will that flower not reproduced at all compared to if that same type of flower received pollen from a different flower of its own species.”
Austin is manipulating various conditions for Jacob’s Ladder to see what happens.
“A third treatment is self-pollination, receiving pollen from the same flower, where a flower simply pollinates itself before any pollen could be transferred from a different species. And while self-pollination is not quite as good as a flower receiving pollen from a different flower of its own species, it’s still better than the reproductive dead end that occurs when a flower receives pollen from a different species.”
After a long pandemic winter, the early cheerful blooms are welcomed by many people. But considering the concerns Austin’s research is addressing, early blooms don’t feel nearly as cheerful when considering the future of flowers and bees.
“We’re similarly concerned about declines of other pollinators, such as butterflies, flies, moths. It’s hard to predict because ecosystems are incredibly complex and interconnected communities,” he said. “And you never know what the cascading effects of one change will have on other organisms.”