LT 7.2 Evidence for Evolution

artificial selection and natural selection

AS: humans, rather than nature, select which individuals in a population reproduce

NS: Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success

The Four Principles of Natural Selection

1. Individuals in a population are genetically different.

2. Variations can be inherited

3. Organisms tend to produce more offspring than the environment can support.

4. Variations give some organisms increased reproduction.

Theory of Evolution

1. Descent with Modification - All present life descended from previous life forms

2. Modification by Natural Selection - Inherited traits allow some organisms to reproduce more successfully than others of the same species

Law of Superposition

In undisturbed rock layers, the oldest rocks are at the bottom

Succession of Forms

Structures in earlier fossils become more elaborate in more modern organisms

Principle of Fossil Succession

Fossil organisms succeed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content

Homologous Structures

Structures that have a common origin, different functions.

Analogus Structures

Structures that have a different origin but common function

Vestigal Structres

These structures are reduced, have a new use, or have no use.

What are 5 molecular features shared by all organisms?

1. DNA/Genetic Code

2. Membranes and Ribosomes (Cell Theory)

3. Glycolysis

4. ATP

5. Replication, Transcription, Protein Syth.

Fossil Record

preserved remains, impression, or trace of any once-living thing from a past geological age.

Biomolecular Similarities

The more similar macromolecules are, the more closely related the species are. idea that organisms living today evolved from earlier organisms.

Imperfections of Adaptions

Adaptations are imperfect because the mutations that would enable perfect adaptation have not arisen.

imperfection adaptations in whales

• the pelvis had evolved to be much reduced in size and separate from the backbone

• whales have lost genes for saliva production and melatonin, which were once useful