lecture_11November_2_without_questions

lecture_11November_2_without_questions - EEMB 120 I...

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Unformatted text preview: EEMB 120 I ntroduction to Ecology November 2, 2010 Vote Today! 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 I nterspecific Competition Resource Gradient (e.g. seed size) Abundance of resource L arge 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 I f only 1 species present, will utilize full range of resource (reduces I ntrasp. 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 I ntersp. Competition Resource Gradient (e.g. seed size) L arge 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) L arge Seeds Small Seeds Frequency of use Species 5 Species 4 Species 3 Species 2 Species 1 Regular Spacing of Species Along Resource Gradients I f species not competing, expect to see random overlap along the resource gradient Resource Gradient (e.g. seed size) L arge 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) L arge 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 ? 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 I nterspecific Competition Competitive Exclusion of a Native Snail by an I ntroduced Snail (Text page 305-306) Competition between mud snails Native snail: Cerithidea californica Batillaria attramentaria introduced into northern California bays in early 1900s Species very similar in resource use, but: Batillaria makes more efficient use of...
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This note was uploaded on 11/11/2010 for the course EEMB 120 taught by Professor Nisbet during the Fall '08 term at UCSB.

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lecture_11November_2_without_questions - EEMB 120 I...

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