Lec 32 2B F09 - BIS2B Fall 2009(Keen Lecture 32 Historical...

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BIS2B Fall 2009 (Keen) Lecture 32 . Historical perspectives 23 November A few issues from the last lecture Corresponding parts in related taxa Puzzles in morphology: vestigial structures. How can two organisms that are not closely related look the same? Students should be able to: Define homology and provide an example Explain how the same structure can be homologous and homoplasious. Explain how natural selection produces homoplasious features and provide an example. Link convergence and homoplasy. Define a vestigial structure and give an evolutionary explanation for its presence.
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Ans. to Student Questions from last lecture: 1. How do cells cope with internal oxygen: the O2 detoxifying enzymes are generally catalase and superoxide dismutase. they convert O- or H2O2 into H2O. there are other ways too. there are common not just to eukaryotes but to all aerobic bacteria. in euks i believe these enzymes are in the cytoplasm 2. A student asked if large-sized plants were removed at the same time as large animals in the Permian and Cretaceous extinctions. This is an interesting question. In the K/T event correlations have been shown between extinction probability and evergreen vs. deciduous habit in angiosperms (the evergreen species were harder hit) but not with trees vs. shrubs vs. herbs. Effects of the P/T event on plants have been less studied - until recently it was thought they were minor, but they're looking much bigger. In the Late Permian of Europe conifers were the dominant plants, but after the event the landscape was dominated by meter-tall lycophytes (Pleuromeia) and conifers didn't come back for a million years or so, but it's not clear whether this was an effect of differential extinction or continuing bad conditions. 3. White chocolate labs: http://www.labbies.com/genetics2.htm
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Cenozoic Era Cenozoic Era 25 25 -35% mammals, one in eight birds, one third of all amphibians and 35% mammals, one in eight birds, one third of all amphibians and 70% of the world 70% of the world ’s assessed plants are in jeopardy according to the s assessed plants are in jeopardy according to the IUCN Red List; link to article in IUCN Red List; link to article in Science Science : : http:// http:// www.sciencemag.org www.sciencemag.org Western gorilla: Western gorilla: population population has declined by more than
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This note was uploaded on 04/21/2010 for the course BIS 2C BIS 2C taught by Professor Rizzo during the Winter '09 term at UC Davis.

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Lec 32 2B F09 - BIS2B Fall 2009(Keen Lecture 32 Historical...

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