ENVS200 Lecture Notes - Lecture 10: Insular Biogeography, Species Pool, Species Richness
12 Apr 2018
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Document Summary
The number of species in a community is referred to as its species richness. Diversity indices are measures that combine both species richness and the evenness or equitability of the distribution of individuals among those species. We can depict the resources available to a community as a one-dimensional continuum, r units long. Each species uses only a portion of this resource continuum, and the lengths of these portions define the niche breadth (n) of each species; the average niche breadth within the community is then n . Some of these niches overlap, and we can measure the overlap between adjacent species by the value o. Productivity hypothesis: this emphasizes the importance of climate in determining productivity at the lowest trophic level the plants and microbes and the resources these then provide for herbivores and then carnivores further up the food chain. Energy hypothesis: emphasizes the direct role of energy (often measured by environmental temperature) on organisms throughout the community.
