Lecture 2 - Evidence for Evolution

Scientific theory

Overarching explanations for how nature works

Scientific law

Rules for how nature will behave under certain conditions

Biogeography

Geographical distribution of a species suggests strongly of a common descent

Endemic species

Species that are unique to specific places

Fossils

Ancient fossilized remains of once living organisms

Fossils formed in ice

Organisms are trapped and preserved in the ice and revealed once the permalayer of ice melts over

Fossils formed in sedimentation

Organisms sink to the bottom of the water and sediments completely cover it, delaying the process of decay. Fossil is revealed as an imprint once the hardened sediment washed away from sea levels changing

Fossils formed in amber

Amber is tree resin that traps small organisms and over time they are fossilized as the resin turns to amber

Characteristics of a good index fossil

1. Abundant

2. Geographically widespread

3. short geograpical time

4. easily recognizable

5. preservable

Isotopes

Has a different number of neutrons

Radioisotopes

Unstable isotopes that brakdown. They are used to show exponential decay

Exponential decay

Constant proportion of radioisotopes break down to stable isotopes in a given time interval. It is unaffected by environmental factors such as moisture, pressure, and temperature

Half-life

How long it takes for 100% to go to 50% of the parent material. The parent material goes INTO the daughter material