Bio171-F08-lec36 - Lecture 36: Monday December 1, 2008...

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Unformatted text preview: Lecture 36: Monday December 1, 2008 Biology 171 Todays Topic: Conservation Biology Announcements Prehistoric & Present Day Extinctions Impacted Ecosystems & Endemicity Prairie, Oceanic Islands, Freshwater & Tropical Rainforests Poster Species - 100 Heartbeat Club Text Reading Lec 36 : 2 nd ed: Chapter 55 (1272-1281) 3 rd ed: Chapter 55 (1249-1260) Lec 37: 2 nd ed: Chapter 50 (1161, 1164); Ch. 55 (1273-1274) 3 rd ed: Chapter 50 (1144-1146); Ch. 55 (1250-1252) 4) This Week in Discussion: Human Diversity Course Evaluations online Final Exam Tues. Dec 16 7-9PM Review Sun. Dec 14 4-6PM 1800 Chem http://www.umich.edu/~eande/tq/speakup_presentation2.ppt On-line course evaluations New this term! There are two distinct patterns of extinction. Background Extinction represents a default rate (1-10% per million years) of loss of species due to normal levels of ecological and biotic turnover. Mass Extinction events reflect cataclysmic planet- wide environmental perturbation, e.g., asteroid impact etc. Present Day Rates of Extinction are approaching that of Mass extinction Events (x100 to x1,000 background rate) Associated with the recent explosive growth in human populations and associated knock-on impact on natural ecosystems. Almost 50% of land surface area has been converted to human use (pastural / agricultural / urban). Over 50% of accessible fresh water used for human consumption At current rates of extinction, >50% of terrestrial plants and animals are in danger of disappearing by the end of the 21st century. Almost 50% of land surface area has been converted to human use (pastural / agricultural / urban). Over 50% of accessible fresh water used for human consumption At current rates of extinction, >50% of terrestrial plants and animals are in danger of disappearing by the end of the 21st century. Not all Human -Induced Extinctions are Recent: End- Pleistocene Megafaunal Extinctions 33 species of North American large mammals went extinct shortly after humans entered the continent and evidence is accumulating that human hunting pressure played an important role in this process. Similar extinctions also occurred in South America, Eurasia and Australia, but not Africa. Some of the Extinct North American Mega Fauna Mastodons Mammoths & American Lions Saber-Tooth Giant Ground Sloth DNA from Mammoth ( Mammuthus- grass eaters) & Mastodon ( Mammut- branch/leaf eaters) fossil teeth can be used to make an Elephant Phylogeny incorporating living and extinct species....
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Bio171-F08-lec36 - Lecture 36: Monday December 1, 2008...

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