EVOLUTION

Chapter 13Chapter 13

Charles Darwin Naturalist- one who Naturalist- one who

observes nature to observes nature to understand how it understand how it came to became to be

Darwin’s Theory of Evolution

Evolution, or change over time, is the , or change over time, is the process by which modern organisms have process by which modern organisms have descended from ancient organisms. descended from ancient organisms.

Voyage of the Beagle

Voyage of Beagle

Dates: Dates: February 12th, 1831February 12th, 1831 Captain:Captain: Charles Darwin Charles Darwin ShipShip: H.M.S. Beagle: H.M.S. Beagle Destination:Destination: Voyage around the world. Voyage around the world. Findings:Findings: evidence to propose a evidence to propose a

revolutionary hypothesis about how life revolutionary hypothesis about how life changes over timechanges over time

Patterns of Diversity

Darwin visited Argentina and Australia which had Darwin visited Argentina and Australia which had similar grassland ecosystems. similar grassland ecosystems.

those grasslands were inhabited by very different those grasslands were inhabited by very different animals. animals.

neither Argentina nor Australia was home to the neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands.sorts of animals that lived in European grasslands.

Living Organisms and Fossils

Darwin collected the preserved remains of Darwin collected the preserved remains of ancient organisms, called ancient organisms, called fossils. .

Some of those fossils resembled organisms Some of those fossils resembled organisms that were still alive today.that were still alive today.

Others looked completely unlike any Others looked completely unlike any creature he had ever seen. creature he had ever seen.

Fossils

One stop included the Galapagos Islands off South America Land TortoisesLand Tortoises

Darwin FinchesDarwin Finches

Blue-Footed BoobyBlue-Footed Booby

Marine IguanasMarine Iguanas

Animals

The Journey Home

Darwin Observed that characteristics Darwin Observed that characteristics of many plants and animals vary of many plants and animals vary greatly among the islands and from the greatly among the islands and from the mainlandmainland

Hypothesis:Hypothesis: Separate species may Separate species may have arose from an original ancestorhave arose from an original ancestor

Ideas that shaped Darwin’s Thinking James Hutton:James Hutton: 1795 Theory of 1795 Theory of

Geological changeGeological change Forces change Forces change

earth’s surface earth’s surface shapeshape

Changes are slowChanges are slow Earth much older Earth much older

than thousands of than thousands of yearsyears

Ideas that Shaped Darwin’s Thinking Charles LyellCharles Lyell Book: Book: Principles of Principles of

GeographyGeography Geographical features Geographical features

can be built up or torn can be built up or torn downdown

Darwin thought if Darwin thought if earth changed over earth changed over time, what about life?time, what about life?

Lamarck

Lamarck’s Theory of Evolution Tendency toward Perfection(Giraffe Tendency toward Perfection(Giraffe

necks)necks)

Use and Disuse (bird’s using forearms)Use and Disuse (bird’s using forearms)

Inheritance of Acquired TraitsInheritance of Acquired Traits

Population Growth Thomas MalthusThomas Malthus--

19th century English 19th century English economisteconomist

If population grew If population grew (more Babies born (more Babies born than die)than die) Insufficient living Insufficient living

spacespace Food runs outFood runs out Darwin applied this Darwin applied this

theory to animalstheory to animals

Publication of Orgin of Species Russel Wallace wrote Russel Wallace wrote

an essay summarizing an essay summarizing evolutionary change evolutionary change from his field work in from his field work in MalaysiaMalaysia

Gave Darwin the drive Gave Darwin the drive to publish his findingsto publish his findings

Natural Selection & Artificial Selection Natural variationNatural variation--differences among --differences among

individuals of a speciesindividuals of a species

Artificial selectionArtificial selection- nature provides the - nature provides the variation among different organisms, and variation among different organisms, and humans select those variations they find humans select those variations they find usefuluseful..

Evolution by Natural Selection

The Struggle for ExistenceThe Struggle for Existence-members of -members of each species have to compete for food, each species have to compete for food, shelter, other life necessitiesshelter, other life necessities

Survival of the FittestSurvival of the Fittest-Some individuals -Some individuals better suited for the environmentbetter suited for the environment

Struggle For Existence & Survival of The Fittest

Natural Selection Over time, natural Over time, natural

selection results in selection results in changes in inherited changes in inherited characteristics of a characteristics of a population. These population. These changes increase a changes increase a species fitness in its species fitness in its environmentenvironment

Descent Descent with ModificationDescent with Modification-Each living organism has -Each living organism has

descended, with changes from other species over timedescended, with changes from other species over time Common DescentCommon Descent- were derived from common ancestors- were derived from common ancestors

Evidence of Evolution The Fossil RecordThe Fossil Record

Geographic Distribution of Living ThingsGeographic Distribution of Living Things

Homologous Body StructuresHomologous Body Structures

Similarities in Early DevelopmentSimilarities in Early Development

Evidence for Evolution The Fossil RecordThe Fossil Record--

Layer show changeLayer show change Geographic Geographic

Distribution of Living Distribution of Living ThingsThings

Homologous Body Homologous Body StructuresStructures

Similarities in Early Similarities in Early DevelopmentDevelopment

Evidence of Evolution The Fossil RecordThe Fossil Record Geographic Geographic

Distribution of Distribution of Living Things-Living Things-similar similar environments have environments have similar types of similar types of organismsorganisms

Homologous Body Homologous Body StructuresStructures

Similarities in Early Similarities in Early DevelopmentDevelopment

Homologous Structures

Homologous StructuresHomologous Structures-structures that -structures that have different mature forms in different have different mature forms in different organisms, but develop from the same organisms, but develop from the same embryonic tissueembryonic tissue

Evidence for Evolution

Vestigial organsVestigial organs-organs that serve -organs that serve no useful function in an organismno useful function in an organism

i.e.) appendix, miniature legs, armsi.e.) appendix, miniature legs, arms

Similarities in Early Development

Summary of Darwin’s Theory Individuals in nature differ from one Individuals in nature differ from one

anotheranother

Organisms in nature produce more Organisms in nature produce more offspring than can survive, and many of offspring than can survive, and many of those who do not survive do not reproduce.those who do not survive do not reproduce.

Summary of Darwin’s Theory

Because more organisms are produce than Because more organisms are produce than can survive, each species must struggle for can survive, each species must struggle for resourcesresources

Each organism is unique, each has Each organism is unique, each has advantages and disadvantages in the advantages and disadvantages in the struggle for existencestruggle for existence

Summary (cont.)

Individuals best suited for the environment Individuals best suited for the environment survive and reproduce most successfulsurvive and reproduce most successful

Species change over timeSpecies change over time

Summary (cont.)

Species alive today descended with modification Species alive today descended with modification from species that lived in the pastfrom species that lived in the past

All organisms on earth are united into a single All organisms on earth are united into a single family tree of life by common descentfamily tree of life by common descent