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Unformatted text preview: Winter 2009 Biology 20C D.C. Potts 1 of 4 File: 20C-W09-L.01-Introduction.doc Printed: 6 January, 2009; 23:38 Bio 20C: ECOLOGY and EVOLUTION Lecture 1 : 7 January 2009 Introduction: Ecology, Evolution and Biodiversity Donald C. Potts 1997-2009 SCOPE of COURSE GEOLOGY + PHYSICS + CHEMISTRY ABIOTIC ENVIRONMENT ABIOTIC ENVIRONMENT + ORGANISMS BIOTIC ENVIRONMEN T ORGANISMS ENVIRONMENT ECOLOGY Major consequences of interactions between organisms and their environments: Environmental Buffering = reduction of extreme physical/chemical/(biological) conditions; without changing average values Habitat Modification = changes in average physical/chemical/(biological) conditions ECOLOGY + GENETICS ADAPTATION ADAPTATION + TIME EVOLUTION ECOLOGY + EVOLUTION BIODIVERSITY BIODIVERSITY + ENVIRONMENT " BIOCOMPLEXITY " Biodiversity consists of all the organisms alive in the world today. It is the culmination of all the evolutionary and ecological processes that have occurred throughout Earth's history. Biodiversity can be represented by the "Tree of Life"- a visual model of all organisms (living or extinct) and their relationships to one another. We call it a "tree" because 19 th century biologists first modeled diversity as branches on a drawing of a tree, with "simpler, primitive" forms near the roots, more "complex, advanced" forms higher up, and primates, including man, at the top. Recent representations are more like a " Web" or " Explosion" of Life than a Tree of Life. Three general levels of biodiversity are now widely recognized, and every organism contributes simultaneously to all three levels: 1. Genetic diversity- among individuals within species 2. Species diversity- different "kinds" of organisms 3. Ecosystem diversity- different assemblages of species and environments Ecology and evolution are different ways of studying the origins, history and nature of biodiverity How we define biodiversity depends on our purpose: evolutionists tend to concentrate on the first two levels (genetic, species), while ecologists tend to emphasize the last two (species, ecosystem). In general usage, "biodiversity" usually refers to "species" diversity. Winter 2009...
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