Evolution & Evolution & Natural Natural Selection Selection What does it mean to evolve? What causes evolution? What evidence do we have for evolution? Vocabular Vocabular y y Evolution Evolution Natural Natural Selection Selection Adaptation Adaptation Overproduction Overproduction Competition Competition Variations Variations Common Common Ancestry Ancestry Homologous Homologous Structures Structures Vestigial Vestigial Organs Organs
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Evolution & Natural Selection What does it mean to evolve? What causes evolution? What evidence do we have for evolution?VocabularyEvolution Natural Selection.
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GSE’sGSE’sGenetic variations are passed on through reproduction. LS3–9aEvidence for evolution illustrates how organisms are related. LS3-9bNatural selection leads to evolution. LS3-9dOur understanding of evolution has changed over time. LS3-9e
VocabularyVocabularyEvolution
Natural Selection
Adaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
EvolutionEvolutionThe theory that organisms change (evolve) over time.
What is a theory?
VocabularyVocabularyEvolutionEvolution
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Why have thoughts Why have thoughts about evolution about evolution changed?changed?We used to think the earth was a few thousand years oldWe now know it is billions of years old from looking at rock samples.We used to think the planet and its inhabitants have not changed since the beginning of time. We now know the planet and its inhabitants have changed, from observing fossils.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
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CompetitionCompetition
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Vestigial OrgansVestigial Organs
FossilsFossils
Jean Pierre LamarkJean Pierre LamarkHis theory was that organisms could change their traits during their lifetime by using them or not using them.These new traits were passed on to offspring and over time the species evolved.Example:
VocabularyVocabularyEvolutionEvolution
Natural Selection
Adaptation
OverproductionOverproduction
CompetitionCompetition
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CommonCommonAncestryAncestry
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FossilsFossilsWe now know this is not possible!
Charles DarwinCharles Darwin(1809-1882)(1809-1882)Proposed the theory of evolution by natural selection
Voyage of the HMS Beagle Five-year journey to various
places across the world
Went to South America and the south pacific collecting specimens and making observations
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Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
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CommonCommonAncestryAncestry
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Vestigial OrgansVestigial Organs
FossilsFossils
Charles DarwinCharles Darwin(1809-1882)(1809-1882)Kept a journal of his findings
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
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CompetitionCompetition
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Vestigial OrgansVestigial Organs
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Observation: Observation: Galapagos FinchesGalapagos FinchesThe finches on each island had different types of beaks. Why do you think that might be?Beaks correspond to the food the birds eat.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Darwin’s Darwin’s HypothesisHypothesisOrganisms had a common ancestor but had adapted to their particular environments and changed over time.
What is an ancestor?
Evolution is due to a process called natural selection.Published his theory in On the Origin of Species in November, 1859
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Natural SelectionNatural SelectionOrganisms best adapted to their environment have a better probability (chance) of surviving and reproducing.
Organisms best adapted to their environment survive and reproduce. This can cause evolution.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
AdaptationAdaptationA trait or behavior that helps an organism survive in its environment.
What two traits do humans have that help us adapt?
Thumbs Language Skills
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Example of Example of AdaptationAdaptationHow are cactuses different from most other plants?
VocabularyVocabularyEvolutionEvolution
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AdaptationAdaptation
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Vestigial OrgansVestigial Organs
FossilsFossils
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Natural Natural selection leads selection leads to evolution! to evolution! Here’s how...Here’s how...OverproductionCompetitionVariations
Overproduction Too many offspring are
produced. Competition
Offspring compete for resources such as food, water, mates, and living space.
Variations Differences in individuals of the
same species. They are passed on through
reproduction.
Important! Important! Variations can make some individuals more adapted to their environment than others. These individuals are more likely to survive and reproduce.
Evidence of Evidence of EvolutionEvolutionCommon AncestryHomologous StructuresVestigial OrgansEmbryo DevelopmentFossils
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
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Common Common AncestryAncestryIf two species evolved from a common ancestor, then they should share some common traits with each other.
Hawaiian Honeycreeper:
Family of birds in Hawaii. They have similar skeletons but each species has a different beak foreating specific foods. Just like the finches Darwin observed!
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Homologous Homologous StructuresStructuresStructures that are similar in two different species.
They suggest that the organismsevolved froma common ancestor.
What do you notice about these 6structures?
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
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HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Vestigial Vestigial OrgansOrgansBody organs that do not serve a purpose.
They may have served a purpose to the ancestors of a species.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
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Vestigial OrgansVestigial Organs
FossilsFossils
Examples of Examples of Vestigial Vestigial OrgansOrgansKiwi, a flightless bird, has wings that serve no known purpose.
Humans have a tailbone. Some scientists suggest that early humans had tails like some other mammals.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
Embryo Embryo DevelopmentDevelopmentWhat do you notice about these embryos? List two observations.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
FossilsFossilsRemains of organisms preserved in rock.
They give us clues about what organisms looked like in the past, and allowus to show how a speciesmay have evolved.
VocabularyVocabularyEvolutionEvolution
Natural SelectionNatural Selection
AdaptationAdaptation
OverproductionOverproduction
CompetitionCompetition
VariationsVariations
CommonCommonAncestryAncestry
HomologousHomologousStructuresStructures
Vestigial OrgansVestigial Organs
FossilsFossils
ONE LAST ONE LAST THING!THING!Darwin said that variation in organisms was a factor of natural selection. But he could not explain what caused variation!
What is DNA?
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DNA is what it’s all DNA is what it’s all about!about!We now know about DNA, the code which determines an organism’s genes.
Mutations in the code (DNA) lead to variation.
Mutations are changes in DNA that can be passed on to offspring.
DNA from different species can be analyzed to see how related they are.