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SESSION 3: What Is the Evidence for Evolution? |
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Facilitator Notes for SESSION 3 |
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Explore Part C
Note 1: Fossilization is a very rare event, so it's unlikely that scientists would
find the direct fossil ancestor of a living species. Vertebrates are more likely to
fossilize because they have hard parts (bones and teeth) and because they are more
recently evolved. Extinction provides opportunities for existing organisms to diversify
into new ecological niches (adaptive radiation). A good example is adaptive radiation of
mammals after dinosaurs became extinct.
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Explain Part A
Note 2: Do the activity as a "jigsaw" Web quest with three teams. Each
team can research one line of evidence (fossil, biogeographical, or anatomical) that
Darwin used to support his theory. For each of the three kinds of evidence, teams will
identify the key evidence, examples that illustrate how that particular line of evidence
supports evolution, and any unanswered questions related to that line of evidence to each
other. Then teams will present their findings.
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Explain Part C
Note 3: Organisms have many common structures: cells, DNA, proteins, enzymes,
biochemical pathways, similarities in different vertebrate forelimbs (homologous
structures -- variations on same bones, used for different functions), similarities in
vertebrate embryos, and similarities in homeobox sequences for vertebrates and Drosophila.
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