Download
1 / 27
270 likes | 284 Views
Explore the Competitive Exclusion Principle by Georgii F. Gause through examples like MacArthur's Warblers, Resource Utilization in Cattails, and competition among species like Cyclotella and Asterionella. Discover how niche differentiation impacts stable coexistence and questions about niche differentiation limits. Delve into Resource Utilization Curves and Grime's C-S-R strategies, examining plant strategies in different environments.
E N D
Competitive Exclusion Principle • "Two competing species cannot coexist in a stable environment if both require the same limiting resource." • if two competing species do coexist in a stable environment, they do so because of niche differentiation - their realized niches are slightly different and thus competition between them is lessened
Limiting Similarity • The competitive exclusion principle led to a whole suite of questions which basically asked: Is there a minimum amount of niche differentiation that has to be exceeded for stable coexistence? • or put another way: Is there a limit to the similarity of coexisting competitors?
Caveats to Resource Utilization Curves 1) Are we examining right resource? Is something else really limiting? 2) Is there variation in when the resource is limiting? If it is only limiting occasionally, then it may not matter much. 3) How do we quantify resource use by species in nature? Do resource utilization curves have to be normal? Does competition change during life history changes in the species? 4) How does overlap really affect the species? Is overlap really only on 1 dimension?
Resource Utilization in Cattails Typha latifolia – shallow 0-60 cm water depth Typha angustifolia – deeper 60-90 cm water depth
Resource Utilization – Spiny Mice Aconomys russatus dirunal but may become nocturnal Aconomys cahirinus nocturnal
Cyclotella Asterionella Two species of competing Diatoms
Species can compete for two resources and can coexist when 2 conditions are met: 1) The habitat must be such that one species is more limited by one resource and the other species is more limited by the other resource. 2) Each species must consume more of the resource that more limits its own growth.
Grime’s C-S-R strategies • Competitive - plants such as perennial herbs, shrubs and trees typically have dense leaf canopies, high growth rates, low seed production and relatively long life spans • Stressful -stress-tolerant plants that often have small evergreen leaves, low growth rates, low seed production and long life spans • Disturbed environments - the plants are primarily Ruderals – plants which are usually small, grow rapidly, short life spans and produce many seeds
