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Processes like completion, predation, ecosystem engineering, etc……. Don’t happen one at a time. Multiple processes are going on simultaneously. competition and disturbance. Natural systems are highly variable, many spp can coexist because the competitive advantages of all spp changing.
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Processes like completion, predation, ecosystem engineering, etc……. Don’t happen one at a time. Multiple processes are going on simultaneously
competition and disturbance Natural systems are highly variable, many spp can coexist because the competitive advantages of all spp changing Factors other than the relative competitive ability of the two spp are important abiotic factors predation
Joseph Connell, coast of Scotland, 1970’s studied 2 barnacles, Chthamalus stellatus & Balanus balanoides. larvae of both spp settle across the intertidal zone, but adults vertically segregated high tide Chthamalus Balanus has heavier shell, individuals grow faster, push Chthamalus off the rocks low tide Balanus
But when Chthamalus is removed, Balanus doesn’t move up intertidal zone Chthamalus has higher tolerance for desiccation
Predation by another species can affect competition Robert Paine, rocky coast of Washington, ‘60’s & ‘70’s, removed predatory starfish Pisaster from plots a f a f c c b e b e d d f f g h g h
a f a c b e f d h f g h Number of species dropped when predators removed Barnacles and mussels were able to crowd out other species Predation by Pisaster kept barnacles and mussels at low levels so don’t crowd out others
Intermediate Disturbance Hypothesis Connell 1978 competitive dominant takes over only spp tolerant of extremes survive # species disturbance (predators, physical conditions, others)
How do you explain their coexistence of 2 spp of chironomids in your pond if you can’t find a resource use difference?