Cane, James .
Do Specialist Bees Better Discriminate Among Their Hybridizing Balsamorhiza Floral Hosts?
Even generalist pollinators are typically taxonomic specialists during individual foraging bouts. Such floral constancy could restrict pollen flow, and thereby gene flow, between otherwise inter-fertile flowering species, thus serving as an ethological mating barrier. Among incipient species, however, floral traits often diverge little. In these cases, foraging infidelity by generalist pollinators (honey bees, bumblebees, hummingbirds) is known to facilitate hybridization. Many other species of bees ľall non-social-- are taxonomic specialists for pollen. Foragers of such oligolectic bees might be more discriminating connoisseurs when choosing among their limited set of floral hosts. If so, they would contribute to positive assortative mating and host plant speciation. Host discrimination was tested with female pollen-foragers of two species of oligolectic Osmia bees foraging freely in randomized mixed arrays of flowers of two sympatric species of Balsamorhiza (Asteraceae), a genus known for hybridization. Females preferred the larger flowered B. macrophylla, but showed no floral constancy whatsoever during individual foraging bouts. Foraging infidelity by these oligolectic bees will contribute to introgression and hybridization where interfertile species of Balsamorhiza meet and flower together. Other genera with hybridizing floral hosts that attract numerous oligolectic bees are reviewed and appear prone to similar outcomes.
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1 - Utah State University, Usda Ars Bee Biology & Systematics Lab, Department Of Biology, Umc-5310, Logan, Utah, 84322-5310, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 2:00 PM