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ECOLOGY TEST #3: BIODIVERSITY STUDY GUIDE Study Sheet #1 Biodiversity Species Diversity Species richness —the number of species in an area (NOT number in a species) Species evenness —the relative abundance of individuals among the species How many species are there? 1.4 Million recorded Estimate for how many are actually out there is in the 10s of millions Also, the number of species increases as species size decreases How has species diversity changed over geologic time (100s millions of years)? MUCH more diversity in the current era compared to the previous one, but generally diversity increased with time with a few exceptions in individual eras How do patterns of species diversity vary geographically (from equator to poles)? Generally diversity increases near the equator—this is a function of Actual Evapotranspiration (AET). AET is the combined loss of water to the atmosphere from Evaporation and Transpiration. AET is a function of temperature (water demand) and precipitation (water supply). Species richness increases as the environment gets warmer and wetter. Extinction: The Loss of Species the cessation of existence of a species or group of animals, reducing biodiversity. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. Possible reasons o Hunt as sport o Food hunt o the unability to survive in changing conditions or against superior competition. The mass extinction in the Cretaceous Period saw the disappearance of the dinosaurs
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The term biodiversity was not termed until mid 1980’s. Extinction of mammal and bird species increase exponentially since the year 1500s (before this – at a very low, continuous rate) What is the major cause of current species extinctions? Habitat destruction done mainly by humans (habitat – the place where organisms live, provides essential resources) threatening human activities o shooting/hunting o deforestation e.g. forest clearing in the Amazon region of Brazil species differ in their susceptibility to extinction o depends on abundance and geographic range Ubiquitous : a species with an extensive geographic range; found in many different locations Endemic : Species restricted in distribution to a particular location; limited geographic distribution What characteristics can increase a species susceptibility to extinction? ~Biodiversity hot spots usually located in the tropics. ~Some species are under pressure because they are incompatible with human populations utilizing adjacent lands. Study Sheet #2
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This note was uploaded on 04/07/2008 for the course EVSC 180 taught by Professor Smith during the Spring '08 term at UVA.

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