bio 5c ch. 54

bio 5c ch. 54 - Species Diversity Outline: Lecture 7....

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1 Species Diversity Lecture 7. Fall.10 Outline: Species Diversity -richness vs. evenness - ranked species abundance curves - Shannon Index, J Trends in Species Diversity a) Environmental harshness - latitude - human effects: pollution i.e., cultural eutrophication, DDT-biomagnification (Next lecture: b) habitat size and isolation; c) disturbance) Key Points from Lecture 6: Earth is a closed system for essential nutrients (e.g., carbon, nitrogen, phosphorus). Need to know how they are converted from inaccessible to accessible forms and recycled (rate and through what pathways). This influences the distribution, abundance, and phenotypes of species and ecological communities. Animals are dependent on plants, microorganisms and decomposers (i.e., fungi and bacteria) for recycling: Inaccessible Accessible Living reservoir reservoir organisms carbon: carbonic acid in oceans CO 2 photosynthesis carbonates in plants to animals . fossil fuel atmosphere respiration nitrogen fixation nitrification nitrogen: (1) N 2 in Soil N plants to animals atmosphere (2) ocean sediments denitrification ammonification (3) N 2 and DIN in oceans sedimentation phosphorus: phosphate dissolved plants to animals rocks inorganic PO 4 weathering Species Diversity Lecture 7
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2 1. Ecological communities are defined as a group of interacting species that live together in the same area. A community may be all interacting species, or for convenience sake, a subset of those species (e.g., the insect community or the bird community). Communities have characteristics that are above and beyond those of the species it contains. Trophic structure is one, species diversity is another. 2. Ecological communities do not all contain the same number of species; yet, some very distinct trends are evident when we compare the number of species found in communities of different biogeographic regions of the Earth. For example, biogeographers and ecologists noted that animals and plants were more abundant and varied in the tropics than in other parts of the world. When we compare the diversity of species found on islands that differ both in size and in distance from mainlands, small or remote islands have fewer
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3 species than large islands and islands closer to the mainland. The regularity of these patterns for different taxonomic groups suggests that patterns in # of species are a result of some set of basic underlying principles rather than accidents of history. Today, we want to consider how some of these trends in species diversity might be explained. 3.
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This note was uploaded on 11/14/2010 for the course BIO 5c taught by Professor Zhu/cardullo/rao during the Fall '08 term at UC Riverside.

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bio 5c ch. 54 - Species Diversity Outline: Lecture 7....

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