What is Evolution?What is Evolution?

EvolutionEvolution- the genetic change of populations - the genetic change of populations over timeover timePopulationPopulation- group of organisms of the SAME - group of organisms of the SAME species that occupies certain areaspecies that occupies certain areaSpeciesSpecies- organisms that can interbreed and - organisms that can interbreed and produce FERTILE offspringproduce FERTILE offspring– Ex) populations in Sauerman Woods Crown Ex) populations in Sauerman Woods Crown

PointPoint

-whitetail rabbits-whitetail rabbits -deer-deer-sparrows-sparrows -squirrels-squirrels

Liger (lion and tiger)-infertileLiger (lion and tiger)-infertile

Cama (camel and llama)-infertileCama (camel and llama)-infertile

How Do We Know Populations How Do We Know Populations Evolve?Evolve?

Population Sampling-Population Sampling- technique uses part technique uses part of population to represent whole of population to represent whole populationpopulation

Capture 100 random rabbits Capture 100 random rabbits – These rabbits are a representation of all the These rabbits are a representation of all the

rabbits in the area.rabbits in the area.– We can study many things within this group…We can study many things within this group…

Genetics of the Population…Genetics of the Population…

Gene Pool-Gene Pool- all of the genes all of the genes of every individual in of every individual in population samplepopulation sampleFrequency-Frequency- how often how often something occurssomething occursPopulation genetics Population genetics involves studying the involves studying the frequency with which certain frequency with which certain alleles occur in a alleles occur in a population’s gene poolpopulation’s gene poolIn 50 years, will the In 50 years, will the allele allele frequencies be the same?frequencies be the same?

Hardy-WeinbergHardy-Weinberg • Hardy-Weinberg Equilibrium PrincipleHardy-Weinberg Equilibrium Principle – – frequencies of the dominant and frequencies of the dominant and

recessive alleles in a population change in time due to 5 things:recessive alleles in a population change in time due to 5 things:• MutationsMutations• MigrationMigration• Natural selection (survival of fittest)Natural selection (survival of fittest)• Small populationSmall population• Non-random mutationNon-random mutation

• If these things occur, then the frequencies change and a population If these things occur, then the frequencies change and a population evolvesevolves

•

QuizQuiz

______________=the genetic change of ______________=the genetic change of populations over time.populations over time.

_____________ =group of organisms of _____________ =group of organisms of the SAME species that occupies certain the SAME species that occupies certain area.area.

_____________=organisms that can _____________=organisms that can interbreed and produce FERTILE offspringinterbreed and produce FERTILE offspring

QuizQuiz

__________=technique uses part of __________=technique uses part of population to represent whole population.population to represent whole population.

__________=all of the genes of every __________=all of the genes of every individual in population sample.individual in population sample.

• frequencies of the dominant and recessive frequencies of the dominant and recessive alleles in a population change in time due alleles in a population change in time due to 5 things:to 5 things:• Mutations, Migration, Natural selection, Small Mutations, Migration, Natural selection, Small

population, Non-random mutationpopulation, Non-random mutation

History of Evolutionary ThoughtHistory of Evolutionary ThoughtBefore 1850, most people believed…Before 1850, most people believed…– Earth formed by supernatural events and never Earth formed by supernatural events and never

changedchanged– Earth only a few thousand years oldEarth only a few thousand years old– Each species was made to fit its environmentEach species was made to fit its environment– Species never changed and did not go extinctSpecies never changed and did not go extinct

Early Scientists’ IdeasEarly Scientists’ IdeasDarwinDarwin deserves credit for the Theory of deserves credit for the Theory of Evolution as we know it todayEvolution as we know it today

He was not the first to come up with the idea:He was not the first to come up with the idea:– Carolus Linnaeus Carolus Linnaeus proposed a new system of proposed a new system of

organization for plants and animals based on their organization for plants and animals based on their similarities (noticed relationships)similarities (noticed relationships)

– Erasmus Darwin Erasmus Darwin considered how organisms could evolve considered how organisms could evolve through mechanisms such as competitionthrough mechanisms such as competition

– Jean-Baptiste Lamarck Jean-Baptiste Lamarck presented evolution as occurring presented evolution as occurring due to environmental change over long periods of timedue to environmental change over long periods of time

Carolus LinnaeusCarolus Linnaeus

Developed a classification Developed a classification system for the huge variety of system for the huge variety of living things he foundliving things he found– Wrote book Wrote book Systema NaturaeSystema Naturae

in 1735 to reveal his in 1735 to reveal his classification systemclassification system

– There are currently 1.9 million There are currently 1.9 million species that have been species that have been identified using his methodidentified using his method

– Linnaeus’s system of classification Linnaeus’s system of classification reflects evolutionary relationshipsreflects evolutionary relationships

Jean Baptiste LamarckJean Baptiste LamarckA French naturalist who proposed that populations of species evolveA French naturalist who proposed that populations of species evolve

His idea proposed: His idea proposed:

– Changes in an environment cause an organism’s behavior to Changes in an environment cause an organism’s behavior to change, leading to greater use or disuse of a structure or organ.change, leading to greater use or disuse of a structure or organ.

– The organism would pass on these acquired changes to its The organism would pass on these acquired changes to its offspring, so a species would change in time.offspring, so a species would change in time.

– Idea called “Evolution by inheritance of acquired characteristics”Idea called “Evolution by inheritance of acquired characteristics”

– Wrong on several accountsWrong on several accounts

Charles DarwinCharles Darwin

At 22, was invited to sail on the At 22, was invited to sail on the “HMS Beagle” “HMS Beagle” – Was going to school to be a Was going to school to be a

minister-believed God created minister-believed God created each species to match its habitat each species to match its habitat and they never changed.and they never changed.

– Thought Earth was about 6,000 Thought Earth was about 6,000 years old and didn’t change, just years old and didn’t change, just like everyone else.like everyone else.

Darwin’s ObservationsDarwin’s ObservationsOne place of note that he One place of note that he visited was the Galapagos visited was the Galapagos IslandsIslands

During journey, he made During journey, he made observations and recorded observations and recorded them in a journal.them in a journal.

Darwin observed fossil and Darwin observed fossil and geologic evidence geologic evidence supporting an ancient supporting an ancient Earth.Earth.

Darwin’s FinchesDarwin’s Finches

When Darwin traveled to the Galapagos he When Darwin traveled to the Galapagos he took interest in the finchestook interest in the finches

He noticed the finch species on the islands He noticed the finch species on the islands were different, but all resembled one from S. were different, but all resembled one from S. America.America.

Darwin thought some migrated and new Darwin thought some migrated and new species evolved.species evolved.

Darwin’s FinchesDarwin’s Finches

This is what Darwin proposed:This is what Darwin proposed:– Finches migrated from South Finches migrated from South

America to the islands.America to the islands.– Populations on different islands Populations on different islands

adapted to different adapted to different environments and food sources environments and food sources they found.they found.

– Those that could survive passed Those that could survive passed on their genes.on their genes.

– Those that couldn’t survive Those that couldn’t survive perished.perished.

Darwin’s FinchesDarwin’s Finches

Over time different Over time different mutations accumulated mutations accumulated in the different finch in the different finch populations on the populations on the different islands.different islands.

The populations The populations divergeddiverged, or became , or became more and more more and more different from each different from each other.other.

Darwin’s FinchesDarwin’s FinchesThe populations on the islands became so different The populations on the islands became so different they no longer mated if they metthey no longer mated if they met

Several new finch species evolved from a common Several new finch species evolved from a common ancestor from S. Americaancestor from S. America

This is an example of macroevolution.This is an example of macroevolution.

Recent finch research

SpeciationSpeciationGeographical isolationGeographical isolation-- members of a population members of a population are separated geographicallyare separated geographically– Major step that leads to speciationMajor step that leads to speciation– Due to volcanoes, earthquakes, flooding, etc.Due to volcanoes, earthquakes, flooding, etc.– Can lead to divergence and then speciationCan lead to divergence and then speciation

Artificial SelectionArtificial SelectionArtificial selectionArtificial selection-- human intervention in animal or human intervention in animal or plant reproduction to ensure that certain desirable plant reproduction to ensure that certain desirable traits are passed ontraits are passed on

Instead of NATURE selecting which traits are Instead of NATURE selecting which traits are favorable, HUMANS selectively breed those animals favorable, HUMANS selectively breed those animals with favorable traitswith favorable traits

Ex. dogs or racehorsesEx. dogs or racehorses

Darwin bred pigeons to Darwin bred pigeons to

explore this idea.explore this idea.

Darwin’s ResultsDarwin’s Results

In 1859, Darwin published In 1859, Darwin published The The Origin of SpeciesOrigin of SpeciesHis book stirred up controversyHis book stirred up controversyIdea called “Evolution by natural Idea called “Evolution by natural selection”selection”

Darwin Video

Darwin’s Book Explained Natural Darwin’s Book Explained Natural Selection Selection

Natural selection-Natural selection- organisms best suited to organisms best suited to their environment survive and reproducetheir environment survive and reproduce

– Darwin’s proposed mechanism of evolutionDarwin’s proposed mechanism of evolution – Survival depends on the particular environmental Survival depends on the particular environmental

conditions a species finds itself in—nature!conditions a species finds itself in—nature!– If the environment changes, so do the populations If the environment changes, so do the populations

that live therethat live there

Adaptation- Adaptation- using inherited genetic using inherited genetic characteristics to increase chance of survival characteristics to increase chance of survival in new environmentin new environmentNatural Selection and SalamandersNatural Selection and Salamanders

Natural SelectionNatural SelectionThree conditions necessary for natural selection to Three conditions necessary for natural selection to occur:occur:– Genetic variationGenetic variation:: Individuals within a population must be Individuals within a population must be

genetically differentgenetically different

****Random mutations are the raw material for evolution to ****Random mutations are the raw material for evolution to occur!!!!!!!occur!!!!!!!

– Overproduction of offspringOverproduction of offspring:: More organisms are born More organisms are born than can survivethan can survive

– Differential reproduction: Differential reproduction: Certain traits enable individuals Certain traits enable individuals to survive and have more offspring than othersto survive and have more offspring than others

Result of Natural SelectionResult of Natural Selection - Genes that help a population survive in their Genes that help a population survive in their

conditions stay in their gene pool, while conditions stay in their gene pool, while “unfavorable” genes gradually decrease in “unfavorable” genes gradually decrease in frequencyfrequency

- This causes changes in the genetics of This causes changes in the genetics of populationspopulations EVOLUTION!!!!! EVOLUTION!!!!!

- As new mutations accumulate over a long time, As new mutations accumulate over a long time, the new populations no longer can mate with the the new populations no longer can mate with the original they started as. New species have original they started as. New species have formed!formed!

Whose idea for evolution is this?

Types of EvolutionTypes of EvolutionEvolutionEvolution - - geneticgenetic change of a change of a populationpopulation of of organisms over timeorganisms over time descent with modification descent with modification

MicroMicroevolution:evolution: Small genetic changes of a populationSmall genetic changes of a populationShorter amount of time Shorter amount of time Peppered moth simulation was Peppered moth simulation was microevolutionmicroevolution

Types of EvolutionTypes of EvolutionMACROMACROevolution-evolution-When When new species are formed new species are formed over long periods of timeover long periods of time– Due to tremendous Due to tremendous

amounts of amounts of accumulated genetic accumulated genetic changes in a populationchanges in a population

– Speciation-Speciation- formation of formation of new species due to new species due to accumulated accumulated microevolution and microevolution and mutationsmutations

EVOLUTIONby natural selection

MACROevolutionMicroevolution

Changes in gene frequencies

in a population

Shorter timesExamples:

Peppered moth and Bengal tiger

Accumulated microevolution and mutations to form whole new species

Longer timesExamples:

Darwin’s finches and geographical isolation

Evidence for EvolutionEvidence for Evolution

Three types of evidence:– Fossils– Anatomical– Molecular

Fossil EvidenceFossil Evidence• Transitional species- species that have

been found in the fossil record that are intermediates between two other species in the evolutionary process

– Radiometric dating- a dating technique that measures amount of radioactive material in a rock or fossil

– Relative dating- a dating technique that estimates the date of a fossil by relating it to the age of the layers of rock around it

Fossil EvidenceFossil Evidence

• To fossilize an organism must be buried by sediment – In swamps, mud, tar

pits, or the ocean bottom

– Hard stuff fossilizes (bones, nails)

– Radiometric and relative dating are used to find out how old the fossil is

Relative Dating

RadiometricDating

Fossil EvidenceFossil Evidence• Fossils show:

– Life has been around for millions of years– Transitional species link older to newer species

– Darwin proposed the idea of transitional species, though he had no evidence

– Today we have evidence:• Archaeopteryx• Tiktaalik Fossil, etc.• Whales

Anatomical EvidenceAnatomical Evidence• Anatomical evidence- evidence for evolution

which is based on similarities and differences between the physical structures of different species.

• What can we tell about the relatedness of the three species below?

Anatomical EvidenceAnatomical Evidence

• Homologous structures- structure is the same (homo) but not function

–Bird wing, dolphin fin, and a human arm–Function these structures is not the same!–Show that these species shared a common

ancestor–Similar structures resulted from accumulated

mutations and modifications

Homologous StructuresHomologous Structures

Anatomical EvidenceAnatomical Evidence• Analogous structures- structure different but serve the same

function–Function = flight–Butterfly wing, bat wing, fly wing

These structures, although they have the same function, are not built the same! similar functions

similar external form different internal structure & development different origin no evolutionary relationship

Analogous structuresAnalogous structures

Solving a similar problem with a similar solutionSolving a similar problem with a similar solution

Don’t be fooledby their looks!

Anatomical EvidenceAnatomical Evidence

Anatomical EvidenceAnatomical Evidence• Vestigial structures-

structures that no longer serve a function

• These structures are the remnants of an evolutionary past and show common anatomy with other species

Molecular EvidenceMolecular Evidence• Molecular evidence-

evidence concerning the comparison of DNA and protein molecules between species

• Ultimate tools for scientists studying evolution

• Same genetic basis for all organisms: A, C, T, and G shows we are all related

Molecular EvidenceMolecular Evidence• Mutations and sexual

reproduction are a cause of variation in a species’ DNA

• DNAmRNAprotein– Transcription- copying the DNA

code into mRNA– Translation- converting the code

of mRNA into a long chain of amino acidsprotein

– Differences in DNA are seen in differences in protein and therefore, traits

Molecular EvidenceMolecular Evidence• Species with more similar DNA are

more closely related on the evolutionary tree– Less time since they

split to accumulate mutations (and, therefore, differences)

– Common ancestor- any species in the past from which two or more related species has evolved

– Evidence for Evolution = speciation event = mutation

How did life begin?How did life begin?

1.)Extraterrestrial origin (Big Bang Theory)

2.)Creation—”divine forces”

3.)From non-living matter (“Chemical Evolution”)--Organic compoundsassembled creating 1st

bacterial cell

How Modern Day Biologists How Modern Day Biologists ClassifyClassify

• 1. Comparing anatomy (physical traits)• 2. Looking at genetic similarities & differences• 3. Biochemical make-ups• 4. Behavioral similarities• Origin of Life Video

CladogramsCladograms• Cladogram- a branching diagram that shows

evolutionary relationships

• We use taxonomy – the science of classifying living things, to help us determine the cladogram