evolution & natural selection what does it mean to evolve? what causes evolution? what evidence...

Evolution & Evolution & Natural SelectionNatural Selection

What does it mean to evolve?

What causes evolution?

What evidence do we have for evolution?

VocabularyVocabularyEvolutionEvolution

Natural SelectionNatural Selection

AdaptationAdaptation

OverproductionOverproduction

CompetitionCompetition

VariationsVariations

CommonCommonAncestryAncestry

HomologousHomologousStructuresStructures

Vestigial OrgansVestigial Organs

FossilsFossils

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







FossilsFossils

EvolutionEvolutionThe theory that organisms change (evolve) over time.

What is a theory?


Natural Selection

Adaptation







FossilsFossils

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.










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:


Natural Selection

Adaptation







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










FossilsFossils

Charles DarwinCharles Darwin(1809-1882)(1809-1882)Kept a journal of his findings










FossilsFossils

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.










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










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.










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










FossilsFossils

Example of Example of AdaptationAdaptationHow are cactuses different from most other plants?










FossilsFossils










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.










FossilsFossils

NATURAL NATURAL SELECTIONSELECTION

(best adapted are able to survive and

reproduce)

NATURAL NATURAL SELECTIONSELECTION

(best adapted are able to survive and

reproduce)

OVERPRODUCTIONOVERPRODUCTION

COMPETITIONCOMPETITION1.2.3.4.

VARIATIONSVARIATIONS

EVOLUTIONEVOLUTION

__________________________________________________________________________________________

EVOLUTIONEVOLUTION

__________________________________________________________________________________________










FossilsFossils

Evidence of Evidence of EvolutionEvolutionCommon AncestryHomologous StructuresVestigial OrgansEmbryo DevelopmentFossils










FossilsFossils

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!










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?










FossilsFossils

Vestigial Vestigial OrgansOrgansBody organs that do not serve a purpose.

They may have served a purpose to the ancestors of a species.










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.










FossilsFossils

Embryo Embryo DevelopmentDevelopmentWhat do you notice about these embryos? List two observations.










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.










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?










FossilsFossils

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.

Combining Evidence:

What does it mean to evolve?

What causes evolution?

What evidence do we have for evolution?

evolution & natural selection what does it mean to evolve? what causes evolution? what evidence...

Documents

theory of evolution

evocabulary evolution

understanding of evolution

beginning of time

darwins hypothesis organisms

charles darwin

billions of years old

galapagos finches