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Habitat filtering influences plant–pollinator interactions in prairie ecosystems

Bizecki Robson, Diana, Hamel, Cary, Neufeld, Rebekah, Bleho, Barbara I.
Botany 2019 v.97 no.3 pp. 204-220
Apidae, Festuca, Syrphidae, bees, botanical composition, ecosystems, flowers, habitats, mixed-grass prairies, pollinators, tallgrass prairies, water content
The xeric hypothesis is that bees are more abundant pollinators than anthophilous flies in dry, temperate biomes, and the habitat filtering hypothesis is that differences in the proportions will impact plant community composition because different pollinators favour different floral traits. However, few studies have examined the predictive value of these hypotheses. In particular, differences in plant–pollinator compositions within biomes, such as the Prairie Ecozone, have not been compared. We documented plant–pollinator interactions and plant abundance in three Canadian prairie types. Flower visits in moist tall grass prairie were mainly by flies in the Syrphidae, whereas visits in the drier fescue and mixed grass prairie were mainly by long-tongued bees in the Apidae. Short-tongued bee visits were not significantly different between the prairie types. Insect visits to tubular, zygomorphic, violet/blue-, and white-flowered plants were higher in drier fescue and mixed grass prairie than in moister tall grass prairie. Further, proportions of plants with these features were lower in the tall grass prairie. Thus differences in the proportion of flies and long-tongued bees, likely affected by habitat conditions including moisture levels, appear to be influencing the types of plants that dominate each prairie type, providing some support for these hypotheses.