Jha and Dick wanted to determine the degree to which native bees, which forage for pollen and nectar and pollinate trees in the process, facilitate gene flow between the remnant forest and adjacent shade-coffee farms.
They focused on Miconia affinis, a small, native understory tree that many farmers allow to invade shade-coffee farms because the trees help control soil erosion.
M. affinis, commonly known as the saquiyac tree, is pollinated by an unusual method known as buzz pollination. In order to release pollen from the tree's flowers, bees grab hold and vibrate their flight muscles, shaking the pollen free. Non-native Africanized honeybees don't perform buzz pollination, but many native bees do.
"Our focus on a buzz-pollinated tree allowed us to exclude Africanized honeybees and highlight the role of native bees as both pollinators and vectors of gene flow in the shade-coffee landscape mosaic," said Jha, a postdoctoral fellow at UC-Berkeley who conducted the research while earning her doctorate at U-M.
Jha and Dick combined field observations with seed-parentage genetic analysis of Miconia affinis. They found that trees growing on shade-coffee farms received bee-delivered pollen from twice as many donor trees as M. affinis trees growing in the adjacent remnant forest. The higher number of pollen donors translates into greater genetic diversity among the offspring of the shade-farm trees.
Seed parentage analysis revealed that pollen from forest trees sired 65.1 percent of the seeds sampled from M. affinis trees growing in a shade-coffee habitat. That finding demonstrates that native bees are promoting gene flow between the remnant forest and the coffee farms---
|Contact: Jim Erickson|
University of Michigan