01 Diversity of Life - 1 What do we mean by the word...

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1 1 What do we mean by the word “diversity?” Socially : variety of genotypes, cultures, ethnicity within a society Biodiversity : Number of species in an area; number of different genera, families, etc. represented in the area; variety of growth forms and life styles 2 How many different kinds of organisms are there on the earth? • 1.5 million described and named • 5-100 million in total? 3 How is diversity threatened? • Natural rate of extinction = • 1/1,000,000 each year • Normally balanced by appearance of new species • Current rate of human-enhanced extinction? • 1000 to 10,000 each year What happens if a species goes extinct? 4 Why are there so many different kinds of organisms on this planet? • Adaptation • Ecological Niches 5 What is an adaptation (adaptive trait)? • A particular characteristic of an organism that enhances its ability to survive or reproduce • May be physical, physiological, or behavioral • Genetically defined (hereditable) • Modifiable from generation to generation (can evolve) 6 What is an ecological niche? • the unique set of traits or adaptations of a species reflects the unique way in which the species interacts with its environment, which is called it’s ecological niche or just niche • No two species share exactly the same niche • According to the competitive exclusion principle, two very similar species will displace one another into different “niche spaces,” or one will go extinct
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2 7 Competitive Exclusion 8 The interactions among organisms help define their niches • A close relationship in which the survival of both partners is enhanced is mutualism (symbiosis in the classical sense) (+/+) • Predation (including parasitism and herbivory) benefit one species while harming the other (+/-) • Competition is harmful to both interacting species (-/-) • What are 0/0, -/0 and +/0 relationships? • (neutralism, amensalism, commensalism)
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This note was uploaded on 02/10/2010 for the course BSC 2010 taught by Professor Essig during the Spring '10 term at University of Southern Maine.

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01 Diversity of Life - 1 What do we mean by the word...

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