Department of Biology at the University of Rochester
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José Arturo Romero, Bob Minckley and Neal Williams (left to right) pondering Sphaeralcea laxa pollination

Calliopsis puellae pair in copula on flower of Calycoseris wrightii

Our finding that specialist bees visit the same plants that attract most generalist bees begs the question of what value specialist bees have to their host, if any. Most studies on pollinator importance of specialist bees have focused on one specialist species without comparison to generalist bee species that are native and use the same floral host. With T’ai Roulston ( and Neal Williams (, we are now asking if specialist bees involved in strongly generalized interactions are notable pollinators of their floral host. Specifically, we are testing the following four predictions that may show specialists make greater pollination contributions than generalists:

  1. Are specialists better pollinators than generalists;
  2. Do specialists show less seasonal and annual variation in abundance than generalists on the same host;
  3. Do generalists’ use of host plants reflect plant species productivity at the community level, and
  4. Are specialists the most important to the reproduction of their host when their host is a relatively poor resource provider in the community.

This project is in its fourth year with support from the National Science Foundation. We have been able to train a number of students from the University of Rochester, Bryn Mawr College, the University of Virginia and Universidad Nacional Autonoma de Mexico and Universidad de San Carlos de Guatemala.