Evidence of Evolution

What are the five types of evidence that support evolution?

1. Fossil Record

2. Homologous Structures

3. DNA (Molecular) Evidence

4. Embryological Development

5. Vestigial Structures

What is the difference between homologous and analogous structures? What are vestigial structures?

Homologous Structures

• Same evolutionary origin.

• Similar anatomy.

• May have different functions.

Analogous Structures

• Different evolutionary origin.

• Same function.

• Result of convergent evolution.

Vestigial Structures

• Reduced structures with little or no current function.

• Example: whale leg bones suggest whales evolved from land mammals.

How can DNA, amino acid sequences, and embryos provide evidence for evolution?

• Species with more similar DNA or amino acid sequences are more closely related.

• Similar embryo development suggests organisms share a common ancestor.

• The greater the similarity, the closer the evolutionary relationship.

Why is the fossil record useful? What are its limitations?

Useful because it:

• Shows organisms that lived in the past.

• Shows transitional forms.

• Helps trace evolutionary change.

Limitations:

• Many organisms never fossilize.

• Fossil record is incomplete.

• Some fossils have been destroyed.

What are gradualism and punctuated equilibrium? Which model is more associated with genetic drift?

Gradualism

• Evolution occurs slowly and continuously over long periods.

Punctuated Equilibrium

• Long periods of little change interrupted by short periods of rapid evolution.

Genetic Drift

• More likely during punctuated equilibrium, especially after events like bottlenecks or founder effects, when populations are small and allele frequencies can change rapidly.