Evolution

Definition: Process of change through time

Theory of Evolution Provides an explanation for the

differences in structure, function, and behavior among life forms

Evolution is based on COMMON ANCESTORY!

One Common Ancestor - Protozoa

Evidence of Evolution

Fossils: Remains of organisms preserved in

sedimentary rock, amber, ice, or tar

Upper Strata – more complex organisms/youngest

Lower Strata – less complex/oldest

Comparative Cytology

The cell is the unifying structure for all living things

Organelles similar in most organisms

Comparative Biochemistry

Nucleic Acids similar in all organisms (DNA/RNA)

Similar proteins (enzymes, hormones) More similarities More closely related

Comparative Anatomy

Similarity in bone structure Homologous Structure: Same

structure different function EX. Arms of humans, flippers of whales,

wings of bat

Homologous Structures

Notice that the types and number of bones are relatively the same.

Comparative Embryology

Similar embryological structure

Common ancestry

***Mature growth is very different from embryological growth.

Comparative Embryology

Notice that as organisms develop they become more and more distinguishable from one another.

Parts that no longer serve a purpose

Structures were used in the past

Genes still produce these structures

Ex. Appendix, tail bone (coccyx)

Vestigial Structure:

Charles Darwin Origin of Species written in 1859

Studied finches, found differences on the Galopogos Islands

Theory of Evolution - evolution based on variation and natural

selection

**Natural Selection: evolution is controlled by nature rather than by people.

Theory of Evolution Based theories on species variation and natural

selection.- (There are 5 points to natural selection)

1.Overproduction- within a population more offspring are born than can possibly survive.

2. Competition- depends on number of individuals in a population struggle for survival

- compete for food, shelter, living space

Darwin (cont.)

3. Survival of the fittest- the “strongest” or best adapted to its environment will survive.

4. Reproduction- individuals that survive will reproduce and transmit favorable traits and variations to offspring.

Darwin (cont.)

5. Speciation- new species have evolved from a COMMON ANCESTOR

Weakness of Darwin’s Theory

Even though Darwin was able to tell us that there were many variations of all living things on the planet…..

-He could not explain why.

-Did not explain how variations arose.

Darwin’s Theory

Hugo DeVries

Hugo DeVries-

- Found that something called a mutation were the source of variation in a population.

- Favorable mutations among competing species resulted in modern species.

Modern Evolutionary Theory

The Modern Evolutionary Theory supports Darwin's theory of variation and natural selection but incorporates the reason for the variation (mutation).

What Produces Variation?

1. Variation: mutation and natural selection.

2. Mutations: spontaneous

3. Sexual reproduction - sorting and recombination of alleles.

Examples of Evolution in Modern Times

1. Peppered Moth: light vs. dark (industrialization

influence) Moth was originally light

in color a mutation occurred moth turned black at same time the trees were getting darker

because of industrialization, those that were dark blended into the trees better and

SURVIVED

2. Insect resistance to insecticide:

Insect gets a mutation and becomes resistant to the

insecticide Resistance is not in

response to insecticide.

(Insecticide=spray that kills insects)

3. Bacteria resistant to penicillin:

One bacteria becomes resistant to PCN bacteria reproduce

ASEXUALLY offspring are also resistant

Modern Evolutionary Theory (cont.)

-involves the struggle of organisms to survive and reproduce in a given environment.

Good traits will passed on and will increase in frequency within a population

Bad traits will decrease in frequency within a population

Geographic Isolation

Favors speciation (development of new species) by segregating a small group from the main population. Ex. Mountains, deserts, cities, bodies of

water.

Reproductive Isolation

As a result of geographic isolation, organisms become so different they cannot mate and produce fertile offspring therefore a new species evolves

2 Theories of Evolution Rate

Gradualism: - evolutionary change is slow, gradual and

continuous.

Punctuated Equilibrium: - long periods of stability interrupted by

significant change.

                                                 

Gradualism Punctuated Equilibrium