Charles darwin & Natural Selection

creationism

the belief that life, the earth, and the universe were created by a divine power

James Hutton and Charles Lyell

helped recognize that earth is billions of years old and that the processes to change the earth back then are the same as they are now

Thomas Malthus

said there is a carrying capacity of earth based on the resources available

Lamarack’s idea of evolution

Law of use and disuse

1. if a body part were used, it got stronger

2. if a body part not used, it deteriorated

use and disuse

An organism could change the size or shape of organ/body parts by using or not using them in its lifetime

Lamarck’s mistakes and contributions

1. He did not know how traits were inherited (through genes)

2. He is credited towards today's modern theory of evolution because he figured out that the environment plays a role in shaping the species that live in it.

Charles Darwin

Naturalist

Published a book called “on the origin of species”, presenting his theory of evolution by natural selection

The Galapagos islands

Animals on island are unique

1. giant tortoises

2. Iguanas

3. Finches

Finches

Finches on the islands resembled a mainland finch

Finches had different beaks adapted to gather different foods

"Survival of the fittest“

Darwin's observations

1. Patterns of diversity that was inheritable

2. Collected fossils of both extant and extinct organisms

3. In nature, populations tend to remain stable in size because of enviornmental factors

4. The production of more individuals leads to competition and struggle for existence within the environment

• Only a fraction survive each generation

Darwin's conclusion

Individuals who inherit characteristics most fit for their environment are more likely to leave more offspring than less fit individuals

Darwin theory of evolution through natural selection

Nature selects which organisms are best able to survive. Organisms with certain adaptations are more likely to survive and reproduce, thus leaving more offspring than other less fit individuals. This leads to the accumulation of favorable traits in the population over generations. If an environment changes over time, natural selection may result in adaptation to these new conditions, and may give rise to new species.

Mechanism of Evolution

1. Overproduction: more offspring then the environment can support

2. Variation: genetic differences exist within a population

3. Adaptation: a trait that increases your chances of surviving can be passed on to the next generation

4. Competition: individuals in population fight for limited resources

5. Selecting agent: part of the environment that determines which individual individuals are most fit

6. Survival of the fittest: organisms best adapted to survive in the environment, survive

Evolution

Evolution occurs as a population of genes and frequencies change overtime

• Change genotype creates new phenotype

How does evolution happen?

Mutations

• Random

• Radiation

• Chemicals

Genetic combination during meiosis

• Crossing over

• Independent assortment

Adaptation

An inherited characteristic that increases an organisms chance for survival

adaptations can be

Physical

Behavioral