lecture 2

1 pa8ent no 2 pa8ent no 3 weeks figure 2213

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Unformatted text preview: –  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) 18 9/30/12 Beak size is heritable •  Offspring resemble their parents. Much of the variation in beak size is due to genetics Daphne Major 19 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 –  Homologies among organisms •  Morphological •  Genetic –  Biogeography –  The fossil record 20 9/30/12 Homology •  Homology –  Is similarity resulting from common ancestry Anatomical Homologies •  Homologous structures between organisms –  Are anatomical resemblances that represent variations on a structural theme that was present in a common ancestor Figure 22.14 Human Cat Whale Bat Molecular Homologies •  Biologists also observe homologies among organisms at the molecular level –  Such as genes that are shared among organisms inherited from a common ancestor 21 9/30/12...
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