Evidence for evolution

Hypothesis

Proposed explanation for an observable phenomenon

Theory

Rules/laws that express relationships between observations from a collection of observations with quantifiable properties

Law

Rules of how nature behaves under certain circumstances

Biogeography

Geographical distribution of species that suggests a common descent

Endemic

Organisms unique/native to a specific area

How are fossils formed in ice?

Rapid freezing and temperature preserves tissues and prevents decay

How are fossils formed through sedimentation?

1. Remains are quickly covered by sediments

2. Sediments harden into rock and organism decays

3. Minerals filter into the hardened rock and form a shape

4. Mineral remains = fossil

How are fossils formed from amber?

Fossilized in tree resin

What makes a good index fossil?

1. Geographically widespread

2. Abundancy

3. Short geological time

4. Easy to recognize and identify

5. Preservable

Isotopes

Different types of atoms for the same chemical element

Radioisotopes

Unstable isotopes that break down and lose radioactive particles UNTIL they become stable

Exponential decay

Constant proportion of radioisotopes that breakdown to stable isotopes in a given time interval

Half life

The time it takes for HALF of the radioisotopes in a sample of rock to breakdown

Transitional forms

A fossil species whose morphology suggests that it was an intermediate transition between one major type of organism to another

Homologous

Same bones with different functions as a result of common ancestry

Homoplasy

Similar functions or characteristics of VERY different species (result of convergent evolution)

Homologous structures

Traits inherited by two different organisms from a common ancestor

Comparative embryology

Closely related species go through similar stages in their embryonic development

Ontogeny

Development of an individual

Phylogeny

Evolutionary history of a species

Vestigial structures

Functionless or nearly functionless structures through to be remnants of a previously evolutionary state

Molecular biology

ALL life shares a universal genetic code

How can we tell how closely related two species are (molecular biology)

1. If amino acid sequences in polypeptides are similar

2. If nucleotide sequence in DNA is similar