lecture 2

Their environment a a ower man8d in malaysia b a s8ck

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Unformatted text preview: erential success in reproduction –  That results from the interaction between individuals that vary in heritable traits and their environment 4 9/30/12 •  Natural selection can produce adaptations of organisms to their environment (a) A flower man8d in Malaysia (b) A s8ck man8d in Africa Figure 22.11 •  If an environment changes over time –  Natural selection may result in adaptation to these new conditions Natural Selection in Action •  Two examples –  Darwin s Finches –  HIV 5 9/30/12 A case study: Natural Selection Darwin s Medium Ground Finch •  Seed eater living on Daphne Major Island •  Drought in 1977 caused 84% mortality •  Only large hard seeds remained for food Evolution by Natural Selection •  Requires heritable variation that affects fitness •  Predicts: –  That survival or mortality should be related to some trait (lets guess beak size) of the organism. –  Variation in the trait is heritable. Larger billed birds tend to survive (variation affected fitness) 6 9/30/12 Beak size is heritable •  Offspring resemble their parents. Much of the variation in beak size is due to genetics Daphne Major 7 9/30/12 The Evolution of Drug-Resistant HIV •  In humans, the use of drugs –  Selects for pathogens that through chance mutations are resistant to the drugs effects •  Natural selection is a cause of adaptive evolution •  Ignoring evolution is dangerous to the public health •  Researchers have developed numerous drugs to combat HIV Percent of HIV resistant to 3TC –  But using these medications select for viruses resistant to the drugs Pa8ent No. 1 Pa8ent No. 2 Pa8ent No. 3 Weeks Figure 22.13 Evolutionary Theory •  Provides a cohesive explanation for many kinds of observations –  Homologie...
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This note was uploaded on 02/06/2014 for the course BILD 3 taught by Professor Wills during the Fall '07 term at UCSD.

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