EVOLUTION

What is evolution? Evolution is the process of gradual change through time Whose name do you associate with the word evolution?

Charles Darwin

1. the birds had a common ancestor After years of studying these birds he concluded the following: 1. the birds had a common ancestor

2. the finches had different niches in order to survive; they had different food sources and different places to live on the island

Based off the study of these finches, Darwin came up with the Theory of Natural Selection

The theory of natural selection states the following: 1. Every species has to compete for food and living space in order to survive

2.organisms better adapted to the environment survive and reproduce more successfully than organisms not as well adapted

3. reproduction leads to genetic variations 4. genetic variation prevents extinction

Comparative Studies Scientist use different types of comparative studies to show that certain organisms have a common ancestor

Types of Comparative studies: 1. Comparative Anatomy The scientist compare skeletal structures of different vertebrates to see if they have a similar basic structure The different types of structures are:

Homologous structures Similar in structure; made up of the same type of bones But have different functions

But different structure Examples: Wings of an insect and a bird Analogous structure Same function But different structure Examples: Wings of an insect and a bird

Vestigial structures Organs that have no useful function, but show evolutionary change Examples: Ear muscles Wisdom teeth Tail bone Appendix tonsil

2. comparative cytology Scientists compare cells and cell organelles of different groups

3.comparative embryology: Comparisons of early embryonic stages of different organisms

Comparative embryology

4. comparative biochemistry Compares DNA or Amino Acid sequence to show evidence of common ancestry

5. Gel Electrophoresis:

Gel Electrophoresis is a complex laboratory technique that is used to analyze DNA, RNA and proteins Mixtures of DNA are cut with restriction enzymes and separated into different size pieces

The DNA pieces are then placed in structures called wells An electric current is applied to the gel creating an electric field inside the gel DNA pieces move towards the POSITIVE pole

The smaller fragments move faster and farther towards the POSITIVE pole The DNA pieces form banding patterns in the gel Organisms with similar banding patterns are more closely related

Phylogenetic tree [family tree] A Phylogenetic tree is a diagram showing the evolutionary interrelations of a group of organisms that come from a common ancestor The ancestor is in the tree “trunk”; organisms that have arisen from it are placed at the ends of tree “branches.”

The distance of one group from the other groups indicates the degree of relationship  closely related groups are located on branches close to one another. 

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