Biology Lecture No. 23: Community Ecology II
Wednesday, November 30 , 2011
-Diversity, trophic levels, complexity
-Patterns in diversity
-Succession, disturbance, more diversity!
-E.g. Chthalamus is a better competitor than Balamus which only exists in deeper waters, in the absence
Species Richness, Species Diversity and Even Diversity:
-Species Richness: Includes the number of different species in a given area.
-Species Diversity: Includes an index that incorporates the number of species in an area and also their
-Even Diversity: Includes the relative abundance or proportion of individuals among the species
-The different classifications for organisms in an ecosystem based on their role as consumers.
-Complex community: Many species per trophic level, and many trophic levels.
-Complex communities are more stable as interconnected life-forms organize a more supportive
Diversity & Keystone Species:
-Keystone species have major effects (relative to the total abundance of species or total biomass) on an
-Keystone species often fall in the sub-category of keystone predators.
-Such keystone predators often increase the species richness. Patterns In Species Behaviour:
- Latitude (Tropics V.s Poles): Mor