Lecture AP Biology Chapter 22B Evidence for evolution

Lecture AP Biology Chapter 22B: Evidence for evolution. After studying this chapter you will be able to understand: Several examples of evidence for evolution; the difference between structures that are homologous and those that are analogous, and how this relates to evolution.

Ch 22 Warm-Up

1. Compare and contrast natural selection vs

artificial selection

2. What are the key ideas of natural selection?

3. Define and give an example for the following:

 Homologous structure

 Vestigial structure

 Analogous structure

Descent with Modification:

A Darwinian View of Life

Part B: Evidence for

Evolution

Recap main ideas of natural selection:

1 Evolution is change in species over time.

2 There is overproduction of offspring, which leads to

competition for resources.

3 Heritable variations exist within a population.

4 These variations can result in differential

reproductive success.

5 Over generations, this can result in changes in the

genetic composition of the population.

Remember:

Individuals do NOT evolve! Populations evolve.

Evidence for Evolution:

1 Direct Observations

2 Fossil Record

3 Homology

4 Biogeography

Evidence for Evolution

1 Direct Observations 2 Fossil Record

Evidence for Evolution:

1 Direct Observations

Examples:

 Insect populations become resistant to pesticides (DDT)

 Antibiotic-resistant bacteria (MRSA)

 Peppered moth (pollution in city vs country)

Evidence for Evolution:

2 Fossil Record

 Fossils = remains or traces of organisms from past

 Found in sedimentary rock

 Paleontology: study of fossils

 Show evolutionary changes that occur over time and origin of major new groups of organisms

Ankle bones

 Prokaryotes (oldest fossils)  eukaryotes (fish –

amphibians – reptiles – birds – mammals)

 Transitional forms = links to modern species

Evidence for Evolution:

3 Homology

 Homology: characteristics in related species can have

underlying similarity even though functions may differ

 Vestigial organs: structures w/little or no use (eg

flightless bird wings)

 Molecular homologies: similar DNA and amino acid

sequences

Molecular

Homologies

 Compare DNA and amino acid sequences

Convergent Evolution

 Distantly related species can resemble one another

 Similar problem, similar solutions!

 Analogous structures: similar structures, function

in similar environments

 Eg Torpedo shape of shark, penguin, & dolphin

Evidence for Evolution:

Rock Pocket Mice Running Time: 10:25 min