FA2008 - BILD 3 - Lecture 04 (Natural Selection - 01)

FA2008 - BILD 3 - Lecture 04 (Natural Selection - 01) -...

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10/8/08 1 Lecture 4 Natural Selection Reading Text Ch. 23 Overview I. Background II. Artificial selection III. Measuring natural selection IV. Different modes of selection Phenotype - the characteristics of an organism, due to both genes and the environment Genotype - genetic composition of an organism Willow ptarmigan ( Lagopus lagopus ). The varied plumages are a response to the environment. At each molt the plumage changes color depending on the season. summer winter Phenotypes Snow geese ( Chen caerulescens ) white and “blue” forms are caused by different versions of a single gene. They occur in the same populations and interbreed. Genotypes Human height Are these different phenotypes or genotypes?
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10/8/08 2 Natural selection - differential survival and reproduction of phenotypes Fitness - contribution an individual makes to the gene pool of the next generation, relative to the contribution of other individuals “Survival of the fittest” II. Artificial selection Artificial selection - natural selection imposed by humans, as in the breeding of crops Rock Pigeon English Carrier pigeon Pouter pigeon Fantail pigeon Many spectacular examples of artificial selection BILD 3 in the news “One gene, a million small dogs” front page LA Times Friday April 6, 2007 Found gene inhibits growth in dogs Present in all small dogs, absent in most large dogs, absent in all wolves
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10/8/08 3 Why would genes show this pattern? “Small” gene:
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This note was uploaded on 03/31/2009 for the course BILD 632282 taught by Professor Henter during the Spring '08 term at UCSD.

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FA2008 - BILD 3 - Lecture 04 (Natural Selection - 01) -...

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