Theory of evolution

• Evolution is the changes that occur in organisms characteristics over time

• Change in a species due to mutation of the DNA code that occurs over a long time

An example ofEvolution

An example of Evolution

An example of Evolution

The Theory of Evolution by Natural Selection

• Charles Darwin theory of evolution through natural selection is the most widely accepted theory

In 1831, Darwin set sail on the ship The Beagle, at age 22 . He studied plant and

animal life of the pacific islands and South America

Galapagos Island- observations of the animal and plant life

here helped Darwin support his theory of Evolution

through Natural Selection.

                                                                                         

                             

His greatest work came from his work with finches

30 years after Darwin’s voyage he wrote a book The Origin of species by means of natural selection. (1859)

                                                                                          

None of these conclusions by Darwin

have ever been disproved.

Natural Selection

Darwin’s theory of evolution through Natural

Selection has 4 main

concepts

All organisms tend to over reproduce.

In any population of organisms individuals will exhibit slight

variation.

All organisms face a constant struggle for survival

Individuals with variations that are favorable for a particular

environment are more likely to survive and pass on those

favorable variations to the next generations

Gradually all offspring of the survivors will make up a larger proportion of the population.

Over many years a population may come to look the same.

Evidence of Evolution

1-DNA sequencing

2- Fossil evidence

3-Adaptation

4- Structural Similarities

5- Embryological Similarities

Evidence of evolution

1-DNA sequence – by comparing the DNA patterns in organisms scientist can determine which organisms are closely related

Evidence of evolution

2-Fossils studying and observing fossils help determine how organisms have evolved

•

Plant Fossil Evidence:

EVIDENCE OF EVOLOTION3-Adaptations: feautres suited to a particular environment that allow organisms to survive

Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat.

Evidence of evolutionMasai people, who live in the arid lands of eastern Africa, have tall, lean bodies that disperse heat well.

Plant Adaptations:

Venus Fly Trap

• Captures Animals

• Acquires Minerals

• For Photo-

synthesis

Help!!!

Evidence of evolution

• Embryological development- as the egg is fertilized the developing organisms show similar patterns of embryological development

Evidence of evolution

1. Anatomical similarities – similar body structures

2. Homologous structures- same origins-different functions

3. Analogous structures- different origins- same functions

4. Vestigial structures- no longer useful

Evidence of evolution• Structures on different organisms are homologous when

they have similar base structures but have different functions.– Human Arm – Bat Wing – Whale Flipper

Evidence of evolution• Analogous structure- structures in different

organisms that have the same functions and are different in structures. Probably had different ancestor ( origins) .

Results of Evolution by way of Natural Selection

• Because of evolution the following results• A)    Organisms are strong and fit • B) Speciation occurs – new organisms are

formed

Speciation

• How does Speciation occur?

1.Geographic isolation 2.Divergent evolution 3.Convergent evolution 4.Gradualism 5.Punctual equilibrium

Geographic Isolation

• Separation of organisms by geographic features

• Mountains• Lakes, oceans,

rivers• Deserts(May result in new

species over time)

Gradualism

• “gradual”

• Small changes

• Over a long time

Punctuated Equilibrium

• “punctuation!”

• Large changes

• Happen rapidly

• Periods of no change

• Gradualism: • Punctuated Equilibrium

Time

#SPECIES

• Divergent evolution- organisms that were similar in structure change and become a new species because the organisms changes to fit and survive in different environments

Divergence

• “diverge”= branch off

• Homologous structures

• Same origin• Same underlying

structure• Difference

functionsOriginal Species:

Mammal

Whale flipper

Human arm

Bat wing

Cat limb

Different origins but have same

features

• Convergent evolution organism that are different and unrelated change and develop similar body structures in order to survive in the environment

•

Convergent EvolutionPlacental mammals

Marsupial mammals