Lec 24 & 25

Lec 24 & 25 - BIS2B Fall 2009 Foodwebs 2. Foodwebs are...

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1 BIS2B Fall 2009 Foodwebs 2. Foodwebs are collections of species with . 1. Direct interactions, between pairs of species, Predator kills prey, disease infects host. Balanus barnacle grows over Cthamalus . Trees shade shorter plants, etc.
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2 large Daphnia sp. small Daphnia sp. alga + + Our Daphnia example is actually a food web of 3 species. Showing direct interactions. Shorter arrow indicates that less energy harvested by smaller than by larger Daphnia species. Showing all interactions. Indirect interactions by dotted line large Daphnia sp. small Daphnia sp. alga Indirect negative interaction of large Daphnia with small Daphnia via the algae food. - + +
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3 Species together ( ) graze algae to lower concentration than D. galatea needs for equilibrium ( λ =1), higher than needed by D. pulicaria. So, D. pulicaria has a stronger competitive effect on D.galatea than on itself. The competitive effect is indirect, via the resource.
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This note was uploaded on 04/21/2010 for the course BIS 2C BIS 2C taught by Professor Rizzo during the Winter '09 term at UC Davis.

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Lec 24 & 25 - BIS2B Fall 2009 Foodwebs 2. Foodwebs are...

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