BIOL 215 Lecture Notes - Lecture 7: Diploblasty, Parazoa, Notochord
11 Mar 2013
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Document Summary
What caused the cambrian explosion as discussed in class: abundant mutations, radiation, climax change, breakup of land masses, though the time period is still too early. Maybe there were too highly specialized: too specialized upon appearance in the fossil record to have originated in the cambrian. Explosion: origin and radiation occur together: geological conditions (snowball theory, rising oxygen levels, predator-prey relationships. Molecular clock: origin first, radiation later: large body size, acquired skeletons - availability of caco3, consider how accurate the fossils are. Radiation facilitated by: highly conserved developmental genes. Of 1. 2 billion (fossils - 500 million) years of animal evolution, modern humans have been on the planet only 200,000 years. Scientists discovered the genes that control development and that these genes are highly conserved across all animals. It turns out that the genes found in fruit flies are shared across all animals. An example is pax6 which is the gene that code for eye development.
