Evolution: A change in a population over time

Causes of Evolution: Natural Selection Migration Mutation

What is Natural Selection? Survival of the ‘fittest’ Occurs through INHERITED adaptations

What is migration? Movement of animals from one area to another. Usually a response to changes in temperature, food supply, or the amount of daylight Two types: emigration and immigration

What is mutation? Permanent alteration of the DNA or genetic material of an organism

How can we tell that populations are evolving? Talk with your group…

How can we tell that populations are evolving How can we tell that populations are evolving? 3 Evidences of Common Ancestry in Evolution: 1. Fossils 2. Anatomy 3. Biogeography

3 Evidences of Evolution 1. Fossils- provide a record of early life even though fossil records are incomplete. The fossil record identifies organisms throughout the geologic time scale.

Archaeopteryx

Which fossil would be the oldest? Which would be youngest, fossil 1 or fossil 2?

2. Anatomy- structural similarities show organisms evolved from a common ancestor Homologous structures- structural features with a common evolutionary origin. They are similar in arrangement and/or function Analogous structures- structures that do not have a common ancestry, but have similar functions (not structure) Vestigial structures- a structure that is still present, but is no longer needed or used. (tailbone, appendix)

Analogous Structures The wings of pterosaurs (1), bats (2) and birds (3) are analogous: they serve the same function and are similar in structure, but each evolved independently.

Vestigial Structures Blind Cave Lizards The Human Appendix Wisdom Teeth in Humans Hind Leg Bones in Whales The Wings on Flightless Birds

3. Biogeography –geographical distribution of plants and animals Geographical distribution of a species Related organisms occur in the same geographic area Most similar to nearest neighbor

Review: Comparing closely related organisms: Dendrograms: Which organisms would be most genetically similar? Which organisms would have the most genetic differences?

Review: Comparing closely related organisms: Cladograms: What trait do Ray-finned fish share with Amphibians? Create an example of a discovery that would challenge the validity of this cladogram.