Section 2:Evidence of Evolution

Evidence of EvolutionEvidence

of Evolution

Similar body structures DNA and proteins

Comparative anatomy

Patterns in early development

Homologous structure

All vertebrates have a tail and rows

of slits in their throats.

Similar DNA mightMean that they

Evolved from the Same acestor

1.Molds and casts2.Petrified fossils3.Trace fossils4preserved remains

Fossils

FORMS OF EVIDENCE

1. Similar body structures2. Patterns of early development3. DNA sequences4. Fossils

Body structures

Comparative anatomy: The comparison of the structures of different organisms.

Homologous structures: Body parts that are structurally similar in related species.

COMPARATIVE ANATOMY

HOMOLOGOUS STRUCTURES

Early Development

In early development, all vertebrates have a tail and tiny slits in their throats.

DNA Sequences

The DNA sequences of different species are similar.

Fossils

4 typesMolds and castsPetrified FossilsTrace FossilsPreserved Remains

Molds and Casts

Petrified Fossils

Trace fossils

Preserved Remains

Learning from Fossils

The fossil record provides evidence about the history of life and past environments on Earth.

Scientists use fossils to study the rate at which evolution has occurred.

Past environments

Fossils can show how an environment has changed: EX. Coal in Antarctica – coal can only form from the remains of plants that grow in warm regions. (hmmm….)

Gradualism

Scientists are not sure how rapidly species change.

Gradualism proposes that evolution occurs.. but it happens steadily – tiny changes in a species gradually add up to major changes over long periods of time.

Fossil record show sudden change (lack of intermediate forms) – incomplete fossil record?

Punctuated Equilibria

This hypothesis states that species evolve quickly during relatively short periods.

Most scientists think that evolution can occur gradually at some times and more rapidly at others.