CHAPTER 13 NOTESCHAPTER 13 NOTES

““THE THEORY OF THE THEORY OF EVOLUTION”EVOLUTION”

I. THEORY OF EVOLUTIONI. THEORY OF EVOLUTION

A. A. EvolutionEvolution - - change change over a over a period of period of timetime

B. B. Charles DarwinCharles Darwin – English – English naturalistnaturalist1. Studied the plants and animals of the 1. Studied the plants and animals of the Galapagos Galapagos

Islands.Islands.2. Noticed that the plants and animals of the 2. Noticed that the plants and animals of the

Galapagos Islands were Galapagos Islands were similarsimilar to those off the to those off the coast of coast of South AmericaSouth America..

3. Suggested that the explanation for this 3. Suggested that the explanation for this similarity was that their similarity was that their ancestorsancestors had had migrated from South America to the Galapagos migrated from South America to the Galapagos Islands.Islands.

4. Published ideas about evolution in his 4. Published ideas about evolution in his book book “Origin of Species”“Origin of Species” – concluded that – concluded that evolution occurs because of evolution occurs because of natural natural selectionselection. .

Four basic concepts:Four basic concepts:A.A.Variations exist among individuals in a Variations exist among individuals in a populationpopulationB.B.Variations can be inheritedVariations can be inheritedC.C.More offspring are produced than can More offspring are produced than can survive.survive.D.D.Variations that increase an organism’s Variations that increase an organism’s chance of surviving and reproducing are chance of surviving and reproducing are more likely t be passed on to the next more likely t be passed on to the next generation.generation.

II. EVOLUTION BY NATURAL II. EVOLUTION BY NATURAL SELECTION SELECTION

A. A. Natural selectionNatural selection – individuals that have traits – individuals that have traits that better suit their environment are more that better suit their environment are more likely to likely to survivesurvive and and reproducereproduce successfully. successfully. ““survival of the fittestsurvival of the fittest””

B. B. Adaptation Adaptation – physical and behavioral traits that – physical and behavioral traits that allow organisms to become better suited to allow organisms to become better suited to their environment.their environment.

1. Ex: 1. Ex: coloring of an animal to blend in to coloring of an animal to blend in to environmentenvironment

2.2. Ex: Ex: thick leaves of a cactus to store waterthick leaves of a cactus to store water

3.3. Penguin adaptations – short wings, dense Penguin adaptations – short wings, dense bonesbones

http://www.gma.org/surfing/antarctica/penguin.html

C. C. Gradualism Gradualism – model of evolution in which – model of evolution in which change occurs at a change occurs at a slowslow, constant rate., constant rate.

D. D. Punctuated EquilibriumPunctuated Equilibrium – model of – model of evolution in which periods of evolution in which periods of rapid changerapid change in a species are separated by periods of in a species are separated by periods of little or no change (possibly caused by little or no change (possibly caused by suden or drastic changes in environment).suden or drastic changes in environment).

III. EVIDENCE OF III. EVIDENCE OF EVOLUTIONEVOLUTION

A. A. Fossils Fossils – provide an actual record of – provide an actual record of

Earth’s past life formsEarth’s past life forms..

1. 1. shells, bonesshells, bones

2. any traces of dead 2. any traces of dead organisms organisms ( (leaf imprint in rockleaf imprint in rock))

3. 3. footprintsfootprints, insects trapped in , insects trapped in tree saptree sap, insects , insects trapped in tartrapped in tar

B. Anatomy and DevelopmentB. Anatomy and Development

1. 1. Vestigial structuresVestigial structures – structures that have – structures that have been reduced in size because they no longer been reduced in size because they no longer serve an important function.serve an important function.

Ex: Ex: hind leg bones of whales, human appendixhind leg bones of whales, human appendix..

2. 2. Homologous structuresHomologous structures – anatomical – anatomical structures from a common ancestor.structures from a common ancestor.

Ex: Ex: forelimbs of vertebratesforelimbs of vertebrates

B. Anatomy and Development (continued)B. Anatomy and Development (continued)

3. 3. Embryo developmentEmbryo development – at some time in – at some time in their development, all vertebrate embryos their development, all vertebrate embryos have a have a finfin, , tailtail, and , and pharyngeal pouchespharyngeal pouches..

4. 4. Biological moleculesBiological molecules – as species evolve, one – as species evolve, one change after another becomes part of their change after another becomes part of their genetic instructions.genetic instructions.

a. Closely related species will show a. Closely related species will show similarities similarities in in nucleotide sequences (DNA).nucleotide sequences (DNA).

b. Closely related species will have similar b. Closely related species will have similar amino acid sequences (proteins)amino acid sequences (proteins)

c. If species have changed over time, their c. If species have changed over time, their genesgenes should have changed. should have changed.

B. Anatomy and Development B. Anatomy and Development (continued)(continued)

IV. EXAMPLES OF IV. EXAMPLES OF EVOLUTIONEVOLUTION

A. Darwin’s FinchesA. Darwin’s Finches

1. Studied 9 distinct 1. Studied 9 distinct speciesspecies

2. All similar except for 2. All similar except for beak shapebeak shape

3. Evolved from 3. Evolved from common common ancestorsancestors

4. Beak shape was 4. Beak shape was affected by the affected by the availability of availability of food.food.

B. Formation of New SpeciesB. Formation of New Species

1. 1. divergencedivergence – the accumulation of – the accumulation of difference between species or difference between species or populations. populations.

Divergence leads to:Divergence leads to:

2. 2. speciationspeciation – process by which – process by which new species formnew species form

3. 3. subspeciessubspecies – populations of the – populations of the same species that differ genetically same species that differ genetically because they have adapted to because they have adapted to different living conditions.different living conditions.