BIOL 300 NOTES 1

BIOL 300 NOTES 1 - derived All life on earth today is...

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FUTUYMA CHAPTER 1 1. All of life on earth today is thought to be descended from how many common ancestors? 2. Darwin's hypothetical tree of life that he included as a figure in chapter 4 of illustrated not only descent from common ancestry, but comprehension of several other evolutionary processes and concepts. 3. What is the difference between a character and a character state? How does this distinction apply to a particular nucleotide position along the DNA molecule, a position at which there may be an A in humans but a G in chimps? 4. Which types of character states are considered the most informative for phylogeny? 5. Opposable toes are present in gibbons, orangutans, gorillas, and chimps. They are absent in humans. Based on phylogeny of the superfamily Hominoidea as presented in Figure 3.3, which of these two character states should be considered ancestral, and which should be considered
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Unformatted text preview: derived. All life on earth today is thought to be descended from a single common ancestor. The Origin That evolution occurs over vast periods of time, and that evolution involves the extinction of species that do not produce competent viable offspring. A character is a genetic trait, such as hair. A character state includes all the biologically possible variances for that character (blonde, brown haired, red-headed). Derived character states. If the ancestral state were non-opposing thumbs, then opposable toes on the feet would have had to evolve independently in gibbons, gorillas, chimps and orangutans. The principle of parsimony requires that we assume the fewest numbers of evolutionary changes. If we do so, we find that humans have to have evolved non-opposable toes independently....
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