EVOLUTION

Chapter 15Chapter 15

In your own words, describe what YOU think the theory of evolution means…

Misconceptions about Evolution

Evolution does not tell us about how life first appeared on EarthEvolution does not tell us about how life first appeared on Earth Individuals do not evolve. Only populations can evolve.Individuals do not evolve. Only populations can evolve. Not all changes are “good”Not all changes are “good” Changes that happen to a person in their lifetime do not always get Changes that happen to a person in their lifetime do not always get

passed on to their childrenpassed on to their children Evolution is not a ladder working towards a better speciesEvolution is not a ladder working towards a better species

Charles Darwin

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.

Patterns of Diversity

Darwin posed challenging questions. Darwin posed challenging questions. Why were there no rabbits in Australia, despite the Why were there no rabbits in Australia, despite the

presence of habitats that seemed perfect for them?presence of habitats that seemed perfect for them?

Why were there no kangaroos in England?Why were there no kangaroos in England?

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

The Galapagos Island

Darwin was fascinated in particular by the land Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos. tortoises and marine iguanas in the Galápagos.

Giant tortoises varied in predictable ways from Giant tortoises varied in predictable ways from one island to another.one island to another.

The shape of a tortoise's shell could be used to The shape of a tortoise's shell could be used to identify which island a particular tortoise identify which island a particular tortoise inhabited. inhabited.

Animals found in the Galapagos

Land TortoisesLand Tortoises

Darwin FinchesDarwin Finches

Marine IguanasMarine Iguanas

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 islandsgreatly among the islands

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

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 Are you still paying Attention?Are you still paying Attention?

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

Peppered Moth• The Peppered Moth is anThe Peppered Moth is an example of example of Natural Selection Natural Selection • During the Industrial RevolutionDuring the Industrial Revolution the trees on which the moth the trees on which the moth rested became covered.rested became covered.• This selected against the allele for paleThis selected against the allele for pale color in the population (which were color in the population (which were poorly camouflaged from predators) poorly camouflaged from predators) and selected for the dark colour alleleand selected for the dark colour allele

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

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

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