biology- chapter 15 powerpoint
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EVOLUTION
Chapter 15Chapter 15
Charles Darwin
Question for Thought
Earth has millions of other kinds of Earth has millions of other kinds of organisms of everyorganisms of every
imaginable shape, size, and habitat. imaginable shape, size, and habitat. This variety of living things is called This variety of living things is called
biological biological diversitydiversity. How did all these different . How did all these different
organisms arise?organisms arise? How are they relatedHow are they related??
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.
A scientific A scientific theory is a well-supported is a well-supported testable explanation of phenomena that testable explanation of phenomena that have occurred in the natural world.have occurred in the natural world.
How do you think Darwin came up with his theory?
Voyage of the Beagle
Voyage of Beagle
Dates: Dates: February 12th, 1831February 12th, 1831 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.
Living Organisms and Fossils Others looked completely unlike any creature he had Others looked completely unlike any creature he had
ever seen. ever seen.
As Darwin studied fossils, new questions arose. As Darwin studied fossils, new questions arose. Why had so many of these species disappeared? Why had so many of these species disappeared?
How were they related to living species?How were they related to living species?
Fossils
The Galapagos Island The smallest, lowest islands were hot, The smallest, lowest islands were hot,
dry, and nearly barren-Hood Island-sparse dry, and nearly barren-Hood Island-sparse vegetationvegetation
The higher islands had greater rainfall and The higher islands had greater rainfall and a different assortment of plants and a different assortment of plants and animals-Isabela- Island had rich animals-Isabela- Island had rich vegetationvegetation..
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
Blue-Footed BoobyBlue-Footed Booby
Marine IguanasMarine Iguanas
Animals
The Journey Home
Darwin observed that characteristics of Darwin observed that characteristics of many plants and animals varied greatly many plants and animals varied greatly among the islandsamong the islands
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 DisuseUse and Disuse
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
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--Layers show changeLayers 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. survive and reproduce.
Species change over time.Species change over time.
Summary (cont.)
Species alive today descended with modifications Species alive today descended with modifications 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