Evidence for Evolution

Chapter 21

Darwin’s Finches and Natrual Selection

• What are the 3 Requirements for Natural Selection to take place?

•

Industrial Melanism and Peppered Moths

• Selection by Predation? New Research

• Kettlewell

• http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/K/Kettlewell.jpg

Artificial Selection

• Fruit Flies

• Crops

• Domesticated Animals ….Pleiotropy???

• http://www.bbc.co.uk/schools/gcsebitesize/img/bidogtree.gif

Fossil Evidence of Evolution

• Age of Fossils can be determined

• Fossils document evolutionary transition

Evolution of Horses

• Changes in Size

• Toe Reduction

• Tooth size and Shape

Anatomical Evidence For Evolution

• Homologous Structures…So what are analogous structures?

• Vestigial Structures

• Early Embryonic Development

Convergent Evolution

Darwin’s Critics

• 1. Evolution is not Solidly Demonstrated• 2. The intelligent design argument• 3. Evolution violates the 2nd law of

thermodynamics• 4.Proteins are too improbable• 5.Natural Selection does not imply evolution• 6. There are no fossil intermediates• 7. The irreducible complexity argument

The Origin of Species

Chapter 22

The Nature of Species

• Sympatric Species

• Subspecies

The Biological Species Concept

• “ A species is a group of actually or potentially interbreeding natural population which is reproductively isolated from other such groups”

• Does not explain all observations

Reproductive Isolation

• Geographic Isolation

• Ecological Isolation

• Behavioral Isolation

• Temporal Isolation

• Mechanical Isolation

• Prevention of Gamete Fusion

• Hybrid Inviability or Infertility

Evolution of Reproductive Isolation

• Selection May reinforce Isolating Mechanisms

• Gene Flow Counters Speciation

• Reinforcement - initially incomplete isolating mechanisms are reinforced by natural selection until they are completely effective

Speciation

• Genetic Drift

• Natural Selection

• Adaptation

• Allopatric

• Sympatric– Polypoidy

Adaptive Radiation

• Hawaiian Drosophila

• Darwins Finches

• Chichlids

Pace of Evolution• Gradualism vs Punctuated Equilibrium

Extinction Through Time

• 5 Mass Extinctions have Occurred in the Past

• Permian, 250 mya

• Cretaceous, 65 mya

• 6th extinction underway

Future of Evolution

• Thoughts????