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Keystone and Dominant Species If some species are more important than others for

ID: 41051 • Letter: K

Question

Keystone and Dominant Species If some species are more important than others for providing community stability, how can we tell which ones they are? Some species play an important role in communities simply because they are the most abundant or have the greatest biomass. These dominant species are often trees and other plants responsible for most of the community?s primary production and physical structure. Rut other, less dominant, species also can have pronounced effects on community dynamics. These keystone species have much bigger effects than would be predicted from their proportional biomass alone. 1 The food web in the figure to the right is a simplified version of a typical community in Yellowstone that includes wolves, coyotes, and the grass Idaho fescue. Look at the sizes of the circles, which represent proportional biomass. The value for proportional biomass,p1, is shown below the name of the species or group. Q43. Based on the food web diagram, which species would you expect to be the dominant species? Pronghorn Idaho Fescue Forbs Elk Simplified food web in Yellowstone National Park. Circle sizes represent proportional biomass in the community.

Explanation / Answer

Idaho Fescue is expected to be the dominant species.