Diversity of Life - Early BeliefsDiversity of Life - Early Beliefs

It was believed that the earth was young.It was believed that the earth was young.

Bishop James Ussher (1581-1656) – using Bishop James Ussher (1581-1656) – using references from scripture – determined that references from scripture – determined that the 1the 1stst day of creation was October 23, day of creation was October 23, 4004 B.C.4004 B.C.

His work was incorporated into an His work was incorporated into an authorized version of the Bible in 1701.authorized version of the Bible in 1701.

Diversity of Life – Early BeliefsDiversity of Life – Early Beliefs

All organisms on Earth were created at All organisms on Earth were created at once, in a once, in a center of creationcenter of creation..

All organisms were created perfectly, well-All organisms were created perfectly, well-designed for the environment they lived in.designed for the environment they lived in.

Organisms shared no common ancestors.Organisms shared no common ancestors.

Scientific evidence began to show Scientific evidence began to show that this explanation was not that this explanation was not completely accurate:completely accurate:

Evidence showed that Earth is very old.Evidence showed that Earth is very old.

Evidence showed that Earth has Evidence showed that Earth has changed a great deal over time.changed a great deal over time.

DiversityDiversity

Evolution: Genetic changes in a species Evolution: Genetic changes in a species over time.over time.

These changes produce new phenotypes These changes produce new phenotypes within a species and lead to the formation within a species and lead to the formation of new species from ancestral forms.of new species from ancestral forms.

Jean-Baptist de LamarckJean-Baptist de Lamarck(1744-1829)(1744-1829)

Law of Use and DisuseLaw of Use and Disuse: organisms : organisms become suited to their environment by become suited to their environment by creating adaptations within their lifetime.creating adaptations within their lifetime.

Inheritance of Acquired CharacteristicsInheritance of Acquired Characteristics: : Those acquired traits are then passed on Those acquired traits are then passed on to future offspring.to future offspring.

Charles Darwin

The Galapagos Islands are volcanic islands located 500 miles west of Ecuador. The organisms Darwin

observed there were all descendants of those brought by wind or currents.

Darwin’s Journey

A Galapagos tortoise and one of the thirteen finch species found among the islands.

Galapagos Islands

Charles DarwinCharles Darwin(1809-1892)(1809-1892)

Recognized the vast biological diversity Recognized the vast biological diversity found on Earth.found on Earth.

The earth is very old and has changed a The earth is very old and has changed a great deal over time.great deal over time.

Organisms have traits that make them Organisms have traits that make them well-suited to a particular environment.well-suited to a particular environment.

Applied the ideas of Malthus to all Applied the ideas of Malthus to all organisms.organisms.

Charles DarwinCharles Darwin

Variation exists in a population.Variation exists in a population.Populations tend to over-produce. This Populations tend to over-produce. This creates a struggle for survival.creates a struggle for survival.Those members of a population with Those members of a population with variations well-suited to the environment will variations well-suited to the environment will survive and pass their traits to future survive and pass their traits to future offspring. offspring. Over time – due to environmental changes, Over time – due to environmental changes, some populations will change, leading to the some populations will change, leading to the formation of new species.formation of new species.

SpeciesSpecies

A group of organisms that naturally A group of organisms that naturally interbreed to produce fertile offspring.interbreed to produce fertile offspring.

Organisms that are of different species will Organisms that are of different species will not interbreed, or if they do their offspring not interbreed, or if they do their offspring typically are not fertile.typically are not fertile.

Natural SelectionNatural Selection

A mechanism where those organisms with A mechanism where those organisms with features best suited to an environment will features best suited to an environment will survive and reproduce.survive and reproduce.

The result of natural selection is a The result of natural selection is a population with phenotypes suited to a population with phenotypes suited to a local environment.local environment.

Alfred Wallace, who independently developedthe same theory as Darwin.

Wallace

Evidence for EvolutionEvidence for Evolution

Radiometric DatingRadiometric Dating

Fossil EvidenceFossil Evidence

Comparative Morphology and EmbryologyComparative Morphology and Embryology

Gene Modification EvidenceGene Modification Evidence

Experimental EvidenceExperimental Evidence

Radiometric EvidenceRadiometric Evidence

How do we know how old the earth really How do we know how old the earth really is?is? A technique for determining the age of objects A technique for determining the age of objects

by measuring the decay of the radioactive by measuring the decay of the radioactive elements they containelements they contain

Uraium-238 vs Lead-206Uraium-238 vs Lead-206

The transformation proceeds at a fixed rate.The transformation proceeds at a fixed rate.

The John Day beds of central Oregon. Sedimentary rocks are formed as layers, one atop another. The oldest rock is deepest and the newest layers are

closest to the surface.

Fossil EvidenceFossil Evidence

Compare fossils from the same geologic Compare fossils from the same geologic layers of sediment , scientists expect to layers of sediment , scientists expect to find similar types of fossils.find similar types of fossils.

When we compare fossil placement with When we compare fossil placement with the dates we get from radiometric dating, the dates we get from radiometric dating, they are very close to being the same.they are very close to being the same.

Fossils

Bird Fossils

Homology

Homologous – the same in structure owing to

inheritance from a common ancestor. It is believed that all four groups of mammals descended from the same ancestor.

Comparative MorphologyComparative Morphology

Morphology is the study of physical forms.Morphology is the study of physical forms.

Forelimbs of a diverse group of mammals Forelimbs of a diverse group of mammals are homologous. are homologous. The 1-2-5 structure has been adapted by the The 1-2-5 structure has been adapted by the

four different groups of mammals in four different groups of mammals in accordance with their varying needs.accordance with their varying needs.

Whale, Cat, Bat, Gorilla

The bones in the forearm are similar in structure despite their variable actions.

Python bones corresponding to the bones of the pelvic girdle in humans. In most vertebrates, the pelvic girdle is attached to the hind limbs but pythons don't have limbs.

Comparative morphology

Comparative EmbryologyComparative Embryology

Embryology is the study of how animals Embryology is the study of how animals develop from fertilization to birth.develop from fertilization to birth.

At a certain point in their development, At a certain point in their development, diverse species all have structures known diverse species all have structures known as pharyngeal slits.as pharyngeal slits. In fish these become gills, in humans they In fish these become gills, in humans they

become the Eustachian tubes.become the Eustachian tubes. All of these animals shared a common All of these animals shared a common

ancestor.ancestor.

Comparative embryology

Gene modification EvidenceGene modification Evidence

Evolutionary theory predicts that there Evolutionary theory predicts that there should be fewer DNA base-pair should be fewer DNA base-pair differences between the genes of similar differences between the genes of similar organisms as compared to those of very organisms as compared to those of very different organisms.different organisms. Human vs. yeastHuman vs. yeast Human vs. pigHuman vs. pig

Many diverse organisms have the same enzyme.

Over time the genetic sequence of the enzyme has been altered.

This chart is a measure of the amount of difference between the enzymes of these organisms.

Experimental evidenceExperimental evidence

Evolutionary change takes place over long Evolutionary change takes place over long periods of time but a carefully planned periods of time but a carefully planned experiment can provide evidence.experiment can provide evidence.

Sex and the Male guppy

In the absence predators, In the absence predators, male guppies grow larger in male guppies grow larger in size and more brightly colored. size and more brightly colored. Female guppies prefer to Female guppies prefer to mate with brightly colored mate with brightly colored males but these males are males but these males are more visible to predators.more visible to predators.

In the presence of predators, In the presence of predators, the male guppy was smaller the male guppy was smaller and drab in color. These and drab in color. These males live longer and produce males live longer and produce more offspring because they more offspring because they live longer.live longer.