Mary McCauley, 2004

Berea College

Do Specialist Pollinators Contribute Anything Special to Generalist Plants?

There are many specialist bees that share a host plant with many generalist pollinators. If the specialist is only one of many pollinators, is their contribution eclipsed by those of the generalists? I studied the floral biology of Physalis subglabrata, a native perennial species of ground cherry in the Solanaceae family, pollinated by one specialist, Colletes latitarsis, and many generalist bees. I considered ways in which the specialist may benefit its host disproportionate to its status as one of several pollinators: 1) it may be a more abundant visitor to its host, 2) it may be a more frequent visitor to its host, 3) it may be a more efficient pollinator of its host and, 4) and it may travel further between populations of its host plant. I found that Colletes latitarsis was the most abundant visitor to Physalis subglabrata at 69%. Colletes was also the most frequent visitor and visited the most flowers (25.6 flowers per hour). There was no statistical evidence that bee species differed in their ability to initiate fruit, but Colletes appeared to be a more effective pollinator. Observation of pollinator movement showed that Colletes did not travel further populations of Physalis, but tended to stay within a single population.


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