It’s All Downhill From Here: Bluebell Gene Dispersal in a Changing Climate
Photo by Ellen Waddle - Bumblebee “robbing nectar” from a bluebell by accessing the nectar from the outside of the flower. Note the pollen the bee is carrying on its leg.
Allison Sayer - CRR Staff
Bluebells are ubiquitous in the Copper Valley, occupying varied habitats and microclimates. They are among the first splashes of color in the brown spring world, and continue to bloom well into summer. They grace our wildest places along with our yards, roadsides, and salads. This common little flower is also being studied by Ellen Waddle to answer some big questions about climate change. Waddle is a Ph.D. student working with Kennicott resident Dr. Dan Doak.
As the climate changes, warmer and drier conditions are moving uphill. With animals, Waddle explained, “as temperature patterns change and precipitation patterns change we expect them to be able to move to follow optimal conditions. We think about ‘climate refugees.’” She continued, “Plants can’t move. Individuals can’t move. The way they can ‘follow their preferred habitats’ is to move seeds or move pollen.”
Bluebells occur over a wide range of altitudes. Clusters of them living in different conditions have adapted over time to their environment. Waddle asks, “When we think about these flowers that we find so pretty, how fast can they move seeds upslope and can they do it fast enough? I remember hiking around, thinking, ‘It’s kind of a lot of work to get uphill.’”
Photo by Ellen Waddle - High-elevation bluebells.
Waddle chose bluebells for a few reasons. “If we’re trying to think about what the future looks like, we want to know how commonplace species are going to respond,” she explained.
The range of altitudes at which they occur also lends itself to the questions surrounding gene flow between altitudes.
“You can find them pretty close to the edge of the glacier all the way to our plots above the treeline,” Waddle said.
The commonness of bluebells provides large sample sizes for statistical analysis.
It is also helpful that Kennicott resident Dr. Bill Morris has already done studies on bluebells in the Kennicott area, exploring their relationship with pollinators.
“It’s nice to work in a system that has a little bit of background knowledge,” she said, “and they’re pretty. That’s always nice. I’m going to be looking at thousands of them.”
Bluebells have relatively large seeds. One would expect that more seeds from uphill plants would roll downhill than the opposite. Is wind enough to blow some seeds uphill from down?
What about pollen? Pollen is transported by bees. Waddle noted, “A bushplane uses more gas to fly uphill.” Bees need more energy to fly uphill as well. She hypothesized bumblebees would not bring pollen uphill from down as frequently as other directions.
If you are wandering in the alpine above Kennicott and encounter a regiment of bluebells growing in a grid amidst a forest of colored toothpicks, you have found one of Waddle’s “common gardens.”
Waddle transplanted individual plants and seeds from a range of elevations to plots at both high and low elevation. This is a technique plant researchers use to distinguish between genetic and environmental factors that affect plant growth and survival.
Photo by Ellen Waddle- The world’s best field assistant.
The common garden set-up has been a fairly athletic component of the research. Getting down to the bottom of the long, straight roots of the plants requires a lot of digging. Waddle said plants growing in talus, especially, have very long roots.
The plants need to be carried to their new homes as quickly as possible. The seeds will take longer to give results. However, the results may be more clear if the transplant process is shown to interfere with plants’ future success.
In addition to jogging up mountains, Waddle has the opportunity to do some extremely zen research: watching bumblebees. “They’re really fun to watch and think about, ‘What strategies are they using?’ We know they’re really smart. We know they’re good at foraging efficiently. How are they responding to steep terrain?”
Waddle said of the bee observations, “It’s really fun. It’s really meditative.” To carry it out, she waits in a plot she has marked out in a field. Bamboo stakes in the ground mark a variety of angles. Waddle notes the direction the bees arrive and depart from, what flowers they visit, and whether they gather pollen, nectar, or both. If she is certain of the species, she notes that as well.
All the data from Waddle’s work is very preliminary. She said that, admittedly unsurprisingly, more seeds disperse downhill as slopes get steeper. She also has noticed changes in the way bees forage up high. “On steep slopes they are less circuitous, [flying with] more directed movement which I think is to conserve energy so they’re not going up and down, up and down.”
Photo by Ellen Waddle- Bluebells ready to be transplanted to a common garden site.
Next year, Waddle plans to carry out transplants at a larger scale. She will also census both the common garden plants and natural populations that are part of her study. She describes that process as “Basically the same as a U.S. census- count the individuals, who reproduced, who survived, who died.”
Waddle is also planning to search for the small ground level burrows Alaskan bumblebees make as nests, using an unusual research assistant: a search and rescue dog. This technique has had some success in Colorado.
Photo by Ellen Waddle- A bee observation plot at the height of summer.
As Waddle’s research continues, she will have more data to report. Meanwhile, she maintains her perspective from each blossom and bee to the planet we all share. “There’s a lot of doom and gloom around what climate change is going to do,” she says, “The best answer is that a lot of species are going to respond differently. I think there’s a lot of value in drilling down into one species in one area to see how it’s going to respond. There’s going to be a lot of variation. There’s value in looking at one flower’s life to get a more holistic view of what the future is going to look like.”
This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-2040434.
