Kooookok

Name Class Date

16.4 Evidence of Evolution

Lesson Objectives

Explain how geologic distribution of species relates to their evolutionary history.

Explain how fossils and the fossil record document the descent of modern species from ancient ancestors.

Describe what homologous structures and embryology suggest about the process of evolutionary change.

Explain how molecular evidence can be used to trace the process of evolution.

Explain the results of the Grants’ investigation of adaptation in Galápagos finches.

Lesson Summary

Biogeography Biogeography is the study of where organisms live now and where they and their ancestors lived in the past. Two biogeographical patterns are significant to Darwin’s theory:

The first is a pattern in which closely related species differentiate in slightly different climates. The Galápagos tortoises and finches follow this pattern.

The second is a pattern in which very distantly related species develop similarities in similar environments. The rheas, ostriches, and emus fall into this pattern.

The Age of Earth and Fossils

Radioactive dating techniques have confirmed that Earth is ancient—approximately 4.5 billion years old.

Recent fossil finds document intermediate stages in the evolution of many groups including whales, birds, and mammals.

Comparing Anatomy and Embryology

Homologous structures are shared by related species and have been inherited from a common ancestor. Similarities and differences among homologous structures help determine how recently two groups shared a common ancestor.

· Body parts that share a common function, but neither structure nor common ancestry, are called analogous structures. Analogous structures do not provide any evidence for evolutionary descent.

· Homologous structures that are greatly reduced in size or have little to no function are called vestigial structures.

· Many homologous structures develop in the same order and in...