BIS 2B Lecture Notes - Lecture 20: Pioneer Species, Competitive Exclusion Principle

• School: UC-Davis
• Department: Biological Sciences
• Course: BIS 2B
• Professor: strauss,gerhart

Document Summary

Defined as a predictable change in species composition through time. Primary: ecosystem built upon barren landscapes after severe disturbance that leaves little biological life. Secondary: occurs in place already occupied and then is disturbed which returns it to earlier point in ecological history. Climatic: changes in community diversity by long term climate change. Pioneer species (often r-life story): have high dispersal, thrive under low competition/harsh conditions. Late successional species are less tolerant of harsh conditions. May be facilitated, inhibited or tolerate pioneer species. How success happens (a to b to c) Facilitation: a helps make suitable environment for b which could make b compete with c. Inhibition: one species inhibits introduction of final species. Neutral (tolerance): each are neutral and the difference in life histories will determine growth. If pioneers are needed to modify environment for later species. If pioneers delay onset of later species/make environment less suitable. Facilitation: ulva modifies environment to make it suitable for gigartina.