macroevolution & origins of life

macroevolution

study of evolution of groups of species over very long periods of time

gradualism

theory that evolutionary change is a steady, slow process

punctuated equilibrium model

change occurs in rapid bursts separated by large periods of stasis (no change)

why is there a debate about the typical pattern of microevolution

because fossil record is incomplete and very hard to test the 2 theories (gradualism & punctuated equilibria model), if we find no fossils for a species over a contested period, how can we determine whether change was occurring?

heterotroph theory

1. volcanoes release gas into atmosphere

2. gases condense to form seas

3. simple organic molecules (fatty acids, glycerol) form

4. cell precursors known as protobionts formed from organic molecules

5. hetertrophic prokaryotes appeared, with the first cells existing as anaerobes

6. autotrophic appeared when mutant heterotroph gained ability to make its own food (photosynthesis)

7. O₂ & ozone layer appear due to photosynthesis output

8. endosymbiotic theory

9. life continues to evolve

miller-urey experiment

showed that several organic compounds could be formed spontaneously by simulating the conditions of Earth’s early atmosphere

RNA world hypothesis

RNA could’ve been the earliest genetic material on earth. A simple RNA molecule could copy itself w/o other molecules, drive chemical reactions, & store genetic info