Concept 18 - Concept 53.2 Dominant and keystone species...

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Concept 53.2 Dominant and keystone species exert strong controls on community structure Species diversity is a fundamental aspect of community structure. A small number of species in the community exert strong control on that community’s  structure, especially on the composition, relative abundance, and diversity of species. The  species diversity  of a community is the variety of different kinds of organisms that  make up the community. Species diversity has two components. Species richness  is the total number of different species in the community. The  relative abundance  of the different species is the proportion each species represents  of the total individuals in the community. Species diversity is dependent on both species richness and relative abundance. Measuring species diversity may be difficult, but is essential for understanding community  structure and for conserving biodiversity. Trophic structure is a key factor in community dynamics. The  trophic structure  of a community is determined by the feeding relationships between  organisms. The transfer of food energy up the trophic levels from its source in autotrophs (usually  photosynthetic organisms) through herbivores (primary consumers) and carnivores  (secondary and tertiary consumers) and eventually to decomposers is called a  food chain. In the 1920s, Oxford University biologist Charles Elton recognized that food chains are not 
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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Concept 18 - Concept 53.2 Dominant and keystone species...

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