SimBio Virtual Labs®
EcoBeaker®: Keystone Predator
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SimBio Virtual Labs®: EcoBeaker®
A diversity of strange-looking creatures makes their home in the tidal pools along the edge of rocky beaches. If you walk out on the rocks at low tide, you’ll see a colorful variety of crusty, slimy, and squishy-looking organisms scuttling along and clinging to rock surfaces. Their inhabitants may not be
as glamorous as the megafauna of the Serengeti or the bird
life of Borneo, but these “rocky intertidal” areas turn out to be great places to study community ecology.
An ecological community is a group of species that live together and interact with each other. Some species eat others, some provide shelter for their neighbors, and some compete with each other for food and/or space. These relationships bind a community together and determine the local community structure: the composition and relative abundance of the different types of organisms present. The intertidal community is comprised of organisms living in the area covered by water at high tide and exposed to the air at low tide.
This laboratory is based on a series of famous experiments that were conducted in the 1960’s along the rocky shore of Washington state, in the northwestern United States. Similar intertidal communities occur throughout the Pacific Northwest from Oregon to British Columbia in Canada. The nine species in this laboratory’s simulated rocky intertidal area include three different algae (including one you may have eaten in a Japanese restaurant); three stationary (or “sessile”) filter-feeders; and three mobile consumers.
Ecological communities are complicated, and the rocky intertidal community is no exception. Fortunately, carefully designed experiments can help us tease apart these complexities, providing insight into how communities function. As will become apparent, understanding the factors that govern community structure can have serious implications for management. In this laboratory, you’ll use simulated experiments to elucidate how interactions between species can play a major role in determining community structure. You will apply techniques similar to those used in the original
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SimBio Virtual Labs® | Keystone Predator
studies, in order to experimentally determine which species in the simulated rocky intertidal are competitively dominant over which others. You’ll then analyze gut contents and use your data to construct a food web diagram. Finally, you’ll conduct removal experiments, observing how the elimination of particular species influences the rest of the community. When you’ve completed this lab, you should have a greater appreciation for the underlying complexity of communities, and for how the loss of single species can have surprisingly profound impacts.
Food Chains, Food Webs and Trophic Levels
You probably know that herbivores eat plants and that predators eat herbivores. The progression of what eats what, from plant to herbivore to predator, is an example of a food chain. Omnivores eat both plants and animals. Within a community, producers, herbivores, predators, and omnivores are linked through their feeding relationships. If you create a diagram that connects different species and food chains together based on these relationships, the result is called a food web diagram. Ecosystems can also be represented by a pyramid comprising a series of “trophic levels”. A species’...
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