Section 2: Evidence of Evolution

Evidence of Evolution Evidence of Evolution Similar body structures Comparative anatomy Homologous structure Patterns in early development All vertebrates have a tail and rows of slits in their throats. DNA and proteins Similar DNA might Mean that they Evolved from the Same acestor 1.Molds and casts 2.Petrified fossils 3.Trace fossils 4preserved remains Fossils

FORMS OF EVIDENCE 1. Similar body structures 2. Patterns of early development 3. DNA sequences 4. 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 types  Molds and casts  Petrified Fossils  Trace Fossils  Preserved 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.