Oct30Lecture

Oct30Lecture - EEMB 120 October 30, 2008 Establish patterns...

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Unformatted text preview: EEMB 120 October 30, 2008 Establish patterns of species composition, resource use or community structure that could result from actions of interspecific competition Determine existence and/or strength of competition using field experiments Study cases of competitive exclusion Establish patterns of co-evolution of competitors character displacement Approaches used in studying Interspecific Competition Competition and Community Structure Competition theory predicts that interspecific competition will affect community structure Some predicted effects: Niche complementarity Regular spacing of species along resource gradients Effects may arise from evolutionary and/or ecological processes Resource Gradient (e.g. seed size) Abundance of resource Large Seeds Small Seeds Regular Spacing of Species Along Resource Gradients Species will be arranged along resource gradients in a pattern that minimizes overlap in resource use Assume a normal distribution for some limiting resource If only 1 species present, will utilize full range of resource (reduces Intrasp. Competition) Species 1 Frequency of use Species 2 Species 2 uses some of the same resources Complete overlap w/ Species 1 Regular Spacing of Species Along Resource Gradients Predict over time, two species will evolve or change resource use to minimize overlap reduces Intersp. Competition Resource Gradient (e.g. seed size) Large Seeds Small Seeds Frequency of use Species 2 Species 1 Expect to see competing species in a community exhibit regular spacing along resource gradient Prevents competitive exclusion Resource Gradient (e.g. seed size) Large Seeds Small Seeds Frequency of use Species 5 Species 4 Species 3 Species 2 Species 1 Regular Spacing of Species Along Resource Gradients If species not competing, expect to see random overlap along the resource gradient Resource Gradient (e.g. seed size) Large Seeds Small Seeds Frequency of use Species 5 Species 4 Species 3 Species 2 Species 1 Compare observed overlaps in resource use with neutral model Resource Gradient (e.g. seed size) Large Seeds Small Seeds Frequency of use Species 5 Species 4 Species 3 Species 2 Species 1 Neutral model without interspecific competition Observed overlap with interspecific competition Ex. N. American lizards (Lawlor) 10 different communities Overlap less than predicted Regular spacing along resource Are differences in resource use larger than predicted by neutral model ? Which of the following are used as evidence for the importance of interspecific competition in ecological communities? A. Low overlap in use of resources by potentially competing species B. Niche complementarity C.Regular spacing of species along a resource gradient D.All of the above Establish patterns of species composition, resource use or community structure that could result from actions of interspecific competition Determine existence and/or strength of competition using field experiments Study cases of competitive exclusion...
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Oct30Lecture - EEMB 120 October 30, 2008 Establish patterns...

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