ENVS CH.11 Outline

ENVS CH.11 Outline - ENVS Ch. 11 Outline Biodiversity 3...

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ENVS Ch. 11 Outline Biodiversity 3 Kinds are necessary 1. Genetic diversity is the variety of the same genes within an individual species. 2. Species diversity is the number of different organisms within one community or ecosystem. 3. Ecological diversity assesses the richness and complexity of a biological community, including the number of niches, trophic levels, and ecological processes that capture energy, sustain food webs, and recycle materials within this system. What are Species? 3 Diff. Definitions 1. reproductive isolation is when all the organisms are potentially able to breed in nature and produce fertile offspring. (Ch. 3) But what about plants and protests, which often reproduce a-sexually or regularly make fertile hybrids? 2. phylogenetic species concept (PSC) which emphasizes the branching relationships among species or higher taxa regardless of whether organisms can breed successfully. 3. evolutionary species concept (ESC) which defines species in evolutionary and historic terms rather than reproductive potential. The advantage here, is that it recognizes that there can be several “evolutionarily significant” populations within a genetically related group of organisms. How many species are there? (refer to Table 11.1 in text) The 1.5 million species already known probably represent only a small fraction of the total number that actually exist. Espeicially in the tropics, researchers estimate that there may be somewhere between 3 million and 50 million different species alive today. Hot Spots have exceptionally high biodiversity:
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Of all of the species identified throughout the world only about 10 to 15% live in North America. The greatest concentration of different organisms tends to be in the tropics, especially in rainforests and coral reefs. Norman Myers, Russell Mittermeirer and others have identified biodiversity hot spots that have at least 1,500 endemics (species that occur nowhere else) and have lost at least 70% of their habitat owing to deforestation or invasive species. They have proposed 34 hot spots that represent a high priority for conservation because they have both high biodiversity and a hish risk of disruption by human activities. (fig 11.4) How do we benefit from Biodiversity? 1. All of our food comes from other organisms Many wild plant species could make very important contributions to human food supplies either as new crops or as a source of genetic material to provide disease resistance or other desirable traits to current domestic crops. Norman Myers estimates that as many as 80,000
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This note was uploaded on 03/26/2008 for the course ENVS 1000 taught by Professor Neff,jason during the Fall '07 term at Colorado.

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ENVS CH.11 Outline - ENVS Ch. 11 Outline Biodiversity 3...

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