plugin-Earth_122_Ch05_notes

plugin-Earth_122_Ch05_notes - 1/15/2009 Introduction to...

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1/15/2009 1 Introduction to Environmental Science: 5. Factors Controlling the Distribution and Abundance of Organisms Earth 122 Prof. Walter A. Illman Factors Controlling the Distribution and Abundance of Organisms Nothing succeeds like excess. Oscar Wilde’s definition of natural selection
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1/15/2009 2 Objectives Describe how environmental factors influence which species live in a given ecosystem and where or how they live. Understand how random genetic variation and natural selection lead to evolution, adaptation, niche specialization, and partitioning of resources in biological communities. Compare and contrast interspecific predation, competition, symbiosis, commensalism, mutualism, and coevolution. Objectives Discuss productivity, diversity, complexity, and structure of biological communities and how these characteristics might be connected to resilience and stability. Explain how ecological succession is changed through time in an ecosystem and the biological communities that occupy it. Give some examples of exotic species introduced into biological communities and describe the effects such introductions can have on indigenous species.
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1/15/2009 3 Outline Who Lives Where, and Why? Natural Selection, Adaptation and Evolution Staying There: Species Interactions Community and Ecosystem Properties Communities in Transition Critical Factors and Tolerance Limits Von Liebig proposed the single factor in shortest supply relative to demand is the critical determinant in species distribution. Shelford later expanded by stating each environmental factor has both minimum and maximum levels, tolerance limits , beyond which a particular species cannot survive.
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1/15/2009 4
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1/15/2009 5 Critical Factors and Tolerance Limits For many species, the interaction of several factors, rather than a single limiting factor, determines biogeographical distribution. For some organisms, there may be a specific
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plugin-Earth_122_Ch05_notes - 1/15/2009 Introduction to...

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