The Rocky Mountain Biological Laboratory is exacting about using non-destructive methodologies so that researchers don't have a negative impact on the bumblebee populations. "When we caught bees to remove target species from the system, or to swab their bodies for pollen, we released them unharmed when our experiments were over," Brosi says. "They're very robust little creatures."
No researchers were harmed either, he adds. "Stings were very uncommon during the experiments. Bumblebees are quite gentle on the whole."
Across the steps of the pollination process, from patterns of bumblebee visits to plants, to picking up pollen, to seed production, the researchers saw a cascading effect of removing one bee species. While about 78 percent of the bumblebees in the control groups were faithful to a single species of flower, only 66 percent of the bumblebees in the manipulated groups showed such floral fidelity. The reduced fidelity in manipulated plots meant that bees in the manipulated groups carried more different types of pollen on their bodies than those in the control groups.
These changes had direct implications for plant reproduction: Larkspurs produced about one-third fewer seeds when one of the bumblebee species was removed, compared to the larkspurs in the control groups.
"The small change in the level of competition made the remaining bees more likely to 'cheat' on the larkspur," Briggs says.
While previous research has shown how competition drives specialization within a species, the bumblebee study is one of the first to link this mechanism back to the broader functioning of an ecosystem.
"Our work shows why biodiversity may be key to conservation of an entire ecosystem," Brosi says. "It has the potential to open a whole new set of studies int
|Contact: Beverly Clark|
Emory Health Sciences