BIO 105 Lecture Notes - Lecture 25: Secondary Succession, Primary Succession, Competitive Exclusion Principle
Document Summary
Keystone predator: predator species with large influence presence on its environment results in difference in environment by its absence e. g. sea stars in the pacific northwest fig. Observation: when sea stars (predator) are present, we have a higher diversity (number) of prey species. When sea stars are absent, there is a lower diversity (number) of prey species. Predictable change in species composition of a community over time, associated with disturbance. Occurs in a lifeless area- no organic material new area available for colonization colonization will occur over time. e. g. area following volcanic activity, glacial retreat: secondary succession: An existing community is disturbed and returns to an earlier stage in the successional sequence e. g. disturbed by fire. Species present in either succession are characterized by trade-offs in their life history r-selected traits: Successional sequence: first a (weeds) b (shrubs) c (small trees) d (large trees) A & b= r-selected, c & d= k-selected.
