- "The Big Bang" theory states that 10 to 20 billion years ago, the once dense universe exploded hurling dust, debris, and gases throughout space. scientist believe the universe is still expanding.
- atoms were formed by this and cooling and compression formed stars and planets.
- The early atmosphere on earth contained only CO2, H2O, CO, H2, N2, NH3, H2S, CH4.(key point, no oxygen present)
- Urey and Miller designed an apparatus that simulated conditions on early earth. They created an experiment showing how earth formed.
- In 1862, Louis Pasteur, using bacteria, proved :life-from-life," or bio-genesis.
- some of the first cells(prokaryotes) flourished at least 3.5 billion years ago, bacteria was unicellular, anaerobic, and heterotrophic.
- The history of earth shows species dying out while others flourish, like the dinosaurs which became extinct in less then 10 million years. fossil record showed that during this time, climate cooled, shallow seas receded and a large meteorite hit the earth.
- MACROEVOLTIOUN = multiplication of species, biological diversity, and evolutioinary novelty. two types, branching and non branching.
- Species is a population whose members have the potensial to interbreed with one another in nature to produce feertile offspring.
- REPRODUCTIVE BARRIERS.
A. Pre-Zygotic barriers-impede mating or hinders fertilization in egg
B. Post-Zygotic barriers-if mating occurs between different species and a zygote is formed, these mechanisms affect the hybrid offspring
- MECHANISMS OF SPECIATION
1. allopatric speciation=physical isolation
2. sympatric speciation=the new population becomes reproductivly isolated in the midst of the parent population
- speeds of speculation
Gradualist model(left) and puntuated equilibrium model(right)
- We can tell geological time of fossils because of sedimentary rock, the deeper, the older. fossils show evidence of macroevolution
- geologists divided time into 4 years:
- another more accurate way of telling of telling fossil time is by radiometric dating. scientists measure the the radiation that fossils emit as they decompose.
- Continents used to be locked up-PANGEA which later broke up and drifted appart
- we did not finish the last slide in class but it can be found on moodle.
Scribe: michael C
Next scribe: xaivier