Fossils provide an objective record of

Evolution

Fossil = A preserved or mineralized remains (bone-petrified tree – tooth – shell) or imprint

of an organism that lived long ago.

Provide record of Earth’s past life-forms. crinoid (800 million yrs old)

pterodactyl (140 -210 million yrs old)

13:2 Evidence of Evolution

1 - Earth is about 4.5 billion years old.

2 – Organisms have inhabited Earth for most of its history.

3 – All organisms living today evolved from earlier, simpler life-forms.

3 Major Points of Scientific Agreement

Changes in a gene’s nucleotide sequence build up over

time.

PROTEINSAnalysis of amino acid sequences

Species that share a common ancestor in a more distant past (humans/frogs) have many amino acid sequence differences.

Species that share a common ancestor more recently (humans/gorillas) have few amino acid sequence differences.

Biological Molecules Contain a Record of Evolution

Nucleic Acids

Scientists can directly estimate the number of nucleotide changes that have taken place in a gene since 2 species diverged from a common ancestor by comparing the exact nucleotides sequence of genes.

Diagram that shows evolutionary relationships

among groups of organisms.

Cladogram

Diagram that shows how organisms are

related through evolution.

PHYLOGENETIC TREES

VESTIGIAL STRUCTURES

Structures in different types of organisms that often reveal basic similarities in anatomy, even though the functions may be very different.

Cormorant

Anatomy and Development Suggest Common Ancestry

Structures that share a common

ancestry.

Homologous Structures

Forelimbs of vertebrates contain the same kinds of bones.

Embryonic Development

A: Gradualism – Model in which gradual change over a long period of time leads to species formation.

B: Punctuated Equilibrium – Model in which periods of rapid change in species are separated by periods of little or no change.