Evolution

=Evolution=

Evolution is the study of how organisms change over time in response to their environment.

__//**Evidence for Evolution**//__
Types of evidence for evolution:

1. Fossil evidence- In fossil evidence, scientists compare fossils of animals to determine how they have changed over time. They use this evidence to see how animals could be related to one another, this is called comparative anatomy. Things that scientists look for include the following structures:

Homologous structures are structures in organisms that came from a common ancestor. These structures have the same internal structure, but may be used for different purposes.
 * Homologous structures**__//**;**//__

EX. The front limb of all 4 legged vertebrates AND humans. We all have the same bones in our fore limbs.... this means that there was a common ancestor to all these organisms.



http://carrier.pbworks.com/f/homologous%20structures.jpg

**Analogous Structures**
Analogous structures are structures that perform the same function, but are structurally different. These structures originated from different ancestors.

Ex. The wings of a bird and the wings of an insect. http://www.bio.miami.edu/dana/pix/analogous.gif

**//__Genetics and Macrobiology__//**
Genes make proteins, which are made up of amino acids. Amino acids and proteins are macromolecules. The more genes two organisms have in common, the more proteins two organisms have in common, the more amino acids two organisms have in common, the more closely related the organisms are.

**//__Natural Selection__//**
Natural selection is survival of the fittest. This means that the organisms that are the best suited to their environment live to pass along there genes. Reproduction is the reason animals are alive---the are alive to pass along their genes.

There are three factors that contribute to natural selection. 1. Variation- There needs to be multiple varieties of the physical characteristics of the gene. 2. Adaptation- One of these variety of genes has to be beneficial to the organism...making them better able to survive in their environment. 3. Heritible- This variation and adaptation must be pass along able to their offspring.

__//**Classification of Organisms**//__
Organisms are classified based on their morphology, cell types and mode of obtaining nutrition. When classifying organisms, there are grouped into smaller and more exclusive groups. This means that the lower on the taxonomic scale you go, the more similar the organisms become.....

Kingdom Phylum Class Order Family Genus Species

Animals in the same genus, MUST belong to the same family, order, class.....etc.

http://www.kirksville.k12.mo.us/khs/teacher_web/alternative/levels_of_classification.jpg

Species are defined as organisms that can reproduce and have offspring that can also reproduce.