EVOLUTION BY NATURAL SELECTION

Darwin and friends

Darwin

Used principles proposed by other scientists

Observations were made during his voyage on the Beagle and through personal experience of breeding domestic animals.

Mechanisms for Evolution

Theory: proposed idea but not proved through scientific experimentation.

Evolution is a theory based on scientific observations.

Today almost all scientists accept that evolution is the basis for the biodiversity of life on Earth.

Evolution by Natural Selection

Darwin observed that: Individuals have physical or behavioral traits

that better suit their environment are more likely to survive and reproduce.

This process is called Natural Selection Organisms differ from place to place because

of the different challenges their ecosystems provide.

Adaptation is used to describe an inherited trait that becomes common in a population.

Natural Selection Example Selection of alleles: alleles are traits that

are specifically selected for in order for the best to survive.

Darwin’s Theory

The results of a random mutation or translation error causes inherited variations in every population or species

In some environments certain individuals are better suited to survive and therefore have more offspring (natural selection).

Darwin’s Theory

The traits that make certain individuals of a population able to survive and reproduce eventually spread throughout that population.

Natural selection can cause changes in the genes of a population.

Lamarck

Lamarck believed that adaptations arose from use and disuse

“either you use it or you lose it” Lamarck and Darwin both believed

acquired traits develop slowly over time.

Species Formation

Species in different locations evolve/change in different directions.

Reproductive isolation: two populations of the same species DO NOT breed with one another due to geographic isolation.

Gradualism vs. Punctuated Equilibrium

Which is which?

The End