10.4 Notes

Biogeography

• Study of organisms' distribution.

Appendix

• Vestigial in humans.

Homologous Structures

• Indicate a common ancestor.

Darwin's Observations

• Similar but distinct species on islands.

Vestigial Structures

• Show common ancestry.
• Unused features.

Fossils

• Show past life.
• Important evidence for evolution.

Darwin's Finches

• Demonstrate local adaptations.

Embryology

• Study of embryos.

Darwin's Evidence

• Fossils and anatomy.

Vestigial Structures

• Unused features.

Structural Patterns

• Clues to the history of a species.

Vestigial Structures

• Lack useful function.
• Underdeveloped/unused features.
• Remnants of organs with past function.
• Example: appendix (digested cellulose).
• Evolved over generations.
• Important for demonstrating evolution.

Anatomy & Homologous Structures

• Comparing body parts of different species.
• Similar structure, different functions.
• Evidence for common descent.
• Unlikely to evolve independently with similar anatomy.
• Example: forelimbs of tetrapods/vertebrates.
• Common ancestor explains homologous structures.

Analogous Structures

• Similar function, different origin.

Evidence for Evolution

• Fossils, geography, embryology, anatomy.

Fossils & Darwin

• Scientists knew organisms changed over time.
• Bottom layers (older), top layers (newer).

Geography

• Island species resemble mainland species.
• Mainland species migrated and adapted differently.
• Darwin established relationship between island and mainland species.

Biogeography

• Study of organism distribution.

Embryology

• Relationship between crabs and barnacles.
• Gill slits in fish become gills; in mammals, ear/throat structures.
• Important for Darwin's common descent evidence.
• Similar embryos suggest distant common ancestor.