Evolution

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EvolutionEvolution

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DefinitioDefinitionn

• Evolution is the gradual,

cumulative change in the heritable characteristics of a population,


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DefinitioDefinitionn

• Theory is a testable scientific explanation of something that is supported by evidencecopyright cmassengale

IntroductionIntroduction Although there seems to be a lot of evidence to Although there seems to be a lot of evidence to

support evolution, there are also people who doubt support evolution, there are also people who doubt the evidence and make a case against evolution. the evidence and make a case against evolution. Many websites can be found supporting the Many websites can be found supporting the concept of evolution. Equally there are many concept of evolution. Equally there are many websites that do not support the concept of websites that do not support the concept of evolution.evolution.

IB students are expected to gain knowledge about IB students are expected to gain knowledge about many aspects of Biology. Since evolution is one of many aspects of Biology. Since evolution is one of these aspects, students are expected to be familiar these aspects, students are expected to be familiar with the concepts presented in this section. At a with the concepts presented in this section. At a personal level, students may choose to accept or personal level, students may choose to accept or reject the possibility of evolution.reject the possibility of evolution.

Taken directly from the IBID Press book, “Biology”Taken directly from the IBID Press book, “Biology”

Topics

I. History of Evolution TheoryII. The Theory of EvolutionIII. Evidence of Evolution

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I. History of I. History of Evolutionary Evolutionary

TheoryTheory


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Charles Darwin Charles Darwin (the father of (the father of

Evolution)Evolution)


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Charles DarwinCharles Darwin An English An English

naturalistnaturalist Went on a 5 Year Went on a 5 Year

Voyage around the Voyage around the world aboard the world aboard the HMS Beagle in the HMS Beagle in the 1830s.1830s.

Collected Plant & Collected Plant & Animal specimensAnimal specimens


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Darwin Left England in Darwin Left England in 18311831

Darwin returned 5 years later in 1836Darwin returned 5 years later in 1836

The Galapagos Islands

Galapagos Islands VideoGalapagos Islands Video

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The Galapagos The Galapagos IslandsIslands

Small Group of Islands 1000 Small Group of Islands 1000 km West of South Americakm West of South America

Very Different ClimatesVery Different Climates Animals On Islands UniqueAnimals On Islands Unique

»TortoisesTortoises»IguanasIguanas»FinchesFinches


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Tortoises


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FinchesFinches

Some finches Some finches looked likelooked like

mainland finchesmainland finches Some finches were different, Some finches were different,

depending on what the available depending on what the available food was (seeds, nuts, berries, food was (seeds, nuts, berries, insects…)insects…)

Finches had Finches had different types of beaksdifferent types of beaks adapted to their adapted to their type of food type of food gatheringgathering



Darwin’s Conclusions

Darwin observed:- PATTERNS OF DIVERSITY- UNIQUE ADAPTATIONS- UNEQUAL DISTRIBUTION

Darwin concluded:

The finches were all one species at one time. When they became isolated from one another, they evolved into different species.

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The process by which organisms The process by which organisms adapt to survive, causing a adapt to survive, causing a gradual change in a population, gradual change in a population, ultimately leading to:ultimately leading to:

New species evolveNew species evolve

DarwinDarwin’’s s

Theory Theory of of

EvolutioEvolutionn


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Publication of Publication of ““On The On The Origin of SpeciesOrigin of Species””

Upon His Return To England, Upon His Return To England, Darwin Developed His Darwin Developed His Observations Into The Theory of Observations Into The Theory of EvolutionEvolution

But He But He Did Not Publish For Did Not Publish For 25 Years25 Years – –

Why?Why?copyright cmassengale

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Darwin Knew That His Theory Darwin Knew That His Theory Would Be Would Be Extremely Extremely ControversialControversial And Would Be And Would Be AttackedAttacked


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Alfred WallaceAlfred Wallace

– Fellow NaturalistFellow Naturalist– Independently Independently

Developed The Same Developed The Same Theory as DarwinTheory as Darwin

– After 25 Years, After 25 Years, Someone Else Had Someone Else Had Come To The Same Come To The Same Conclusions From Conclusions From Their Observations Of Their Observations Of NatureNature


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Darwin Presented WallaceDarwin Presented Wallace’’s s Essay & Some Of His Work At A Essay & Some Of His Work At A Scientific Conference in Scientific Conference in 18581858

Then He Started On his book Then He Started On his book ““Origin of SpeciesOrigin of Species””

It Took Darwin 18 Months To It Took Darwin 18 Months To Complete The BookComplete The Book


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•Struggle for ExistenceStruggle for Existence•Survival of the FittestSurvival of the Fittest•Natural SelectionNatural Selection•Descent with ModificationDescent with Modification

DarwinDarwin’’s Key s Key IdeasIdeas


Other scientistsOther scientists


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James HuttonJames HuttonScottish Geologist, Scottish Geologist, 17951795Theory of Geological ChangeTheory of Geological Change

–Changes in Earth are Changes in Earth are due to due to slow, slow, continuous processescontinuous processes..–Aka Aka GradualismGradualism

–The Earth is millionsThe Earth is millionsOf years old.Of years old.


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Charles LyellCharles Lyell Wrote the book, Wrote the book,

““Principles of Principles of GeologyGeology””

Geological Geological processes happen processes happen slowlyslowly

Proposed that the Proposed that the Earth was millions Earth was millions of yearsof years instead of instead of a few thousand a few thousand years oldyears old


Jean-Baptiste LamarckJean-Baptiste Lamarck

Discovered: Discovered: 1.1. Tendency TowardTendency Toward

PerfectionPerfection

2. Law of Use and Disuse2. Law of Use and Disuse

3. Inheritance of3. Inheritance of

Acquired Traits.Acquired Traits.


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LamarckLamarck’’s Theory of s Theory of EvolutionEvolution

1. 1. Tendency Toward PerfectionTendency Toward Perfection Organisms Are Continually Organisms Are Continually

Changing and Acquiring Changing and Acquiring Features That Help Them Live Features That Help Them Live More Successfully In Their More Successfully In Their EnvironmentEnvironment

Example:Example: Butterflies need to hide Butterflies need to hide better from predators, so their better from predators, so their camouflage continues to improve.camouflage continues to improve.

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2. Law of Use 2. Law of Use and Disuseand Disuse

If a body part If a body part were used, it were used, it got strongergot stronger

If body part If body part NOT used, it NOT used, it disappeareddisappeared


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3. 3. Inheritance of Acquired Inheritance of Acquired TraitsTraits

– Inherited Trait Inherited Trait – trait that I– trait that I’’m m born with because its coded for born with because its coded for by my DNA.by my DNA.

– Acquired Trait Acquired Trait – trait that I– trait that I’’m not m not born with, but rather that I born with, but rather that I develop in my lifetime.develop in my lifetime.


Inherited TraitsInherited Traits Acquired TraitsAcquired Traits


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3. 3. Inheritance of Acquired Inheritance of Acquired TraitsTraits

Acquired Traits Acquired Traits – Fluffier FeathersFluffier Feathers– Bigger MusclesBigger Muscles– Clipped EarsClipped Ears

These These Traits Could Then Be Traits Could Then Be Passed On To Their OffspringPassed On To Their Offspring

Over Time This Led To Over Time This Led To New New SpeciesSpecies



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LamarckLamarck’’s Mistakess Mistakes

Lamarck Did NOT Know how Lamarck Did NOT Know how traits were traits were inherited (Traits inherited (Traits are passed through genes)are passed through genes)

Genes Are NOT Changed By Genes Are NOT Changed By Activities In LifeActivities In Life

Change Through Change Through Mutation Mutation Occurs Before An Organism Occurs Before An Organism Is BornIs Born


Thomas MalthusThomas Malthus

Struggle for ExistenceStruggle for Existence– If the human population continues to If the human population continues to

grow unchecked, sooner or later there grow unchecked, sooner or later there would be insufficient living space and would be insufficient living space and food for everyone.food for everyone.


Importance to DarwinImportance to Darwin What causes death?What causes death? What causes survival?What causes survival?

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Evolutionary TimelineEvolutionary Timeline


Topics

I. History of Evolution TheoryII. The Theory of EvolutionIII. Evidence of Evolution

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II. The Theory of II. The Theory of EvolutionEvolution


Key IdeasKey Ideas

1. 1. Struggle for ExistenceStruggle for Existence

2.2. Survival of the FittestSurvival of the Fittest

3.3. Natural SelectionNatural Selection

4.4. Descent with ModificationDescent with Modification


#1#1

Struggle for ExistenceStruggle for Existence(Species compete for food, (Species compete for food, mates, space, water, etc. in mates, space, water, etc. in

order to survive.)order to survive.)


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Struggle for ExistenceStruggle for Existence

Populations cannot grow indefinitely because resources (food, space, etc.) are limited

Species are forced to compete for those resources.


Struggle for Existence Videos

Desert

Insect Competition

#2#2

Survival of the FittestSurvival of the Fittest(Individuals that are (Individuals that are better better

suited to their environments suited to their environments survive and reproduce better survive and reproduce better

than those who are not.)than those who are not.)


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Survival of the FittestSurvival of the Fittest

Fitness– Ability of an Individual To Ability of an Individual To

Survive & Reproduce in its Survive & Reproduce in its specific environmentspecific environment

Adaptation– Inherited Characteristic That Inherited Characteristic That

Increases an Organisms Increases an Organisms Chance for SurvivalChance for Survival


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Survival of the FittestSurvival of the Fittest

Adaptations Can Be:–Physical

»Speed, Camouflage, Claws, Speed, Camouflage, Claws, Quills, etc.Quills, etc.

– BehavioralBehavioral»Solitary, Herds, Packs, Solitary, Herds, Packs, Activity, etc.Activity, etc.


Adaptations

#3#3

Natural SelectionNatural SelectionThe process by which individuals with characteristics most fit for

their environment are “selected” to survive and those least fit DO NOT

survive.


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Artificial SelectionArtificial Selection

Artificial SelectionArtificial Selection– Selective Breeding To Selective Breeding To

Enhance Desired Traits Enhance Desired Traits Among Livestock or CropsAmong Livestock or Crops


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Artificial SelectionArtificial Selection

Key Concept:Key Concept:

In In Artificial SelectionArtificial Selection,, NatureNature Provided The Provided The Variation Among Different Variation Among Different Organisms, And Organisms, And HumansHumans Selected Those Variations Selected Those Variations That They Found UsefulThat They Found Useful



In In Natural SelectionNatural Selection,, NatureNature Provides The Provides The Variation Among Variation Among Different Organisms, Different Organisms, And And NatureNature selects those selects those that will survivethat will survive

5 Points of Darwin’s 5 Points of Darwin’s Natural SelectionNatural Selection


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5 Points of Natural 5 Points of Natural SelectionSelection

1.1. A population has A population has variations.variations.

VariationVariation

Sexual reproduction promotes Sexual reproduction promotes variationvariation

– Independent assortment in meiosisIndependent assortment in meiosis– Crossing over in meiosisCrossing over in meiosis


Independent AssortmentIndependent Assortment


Crossing OverCrossing Over


Both independent Both independent assortment and assortment and crossing over crossing over cause cause gametes to gametes to differ differ from each from each other resulting in other resulting in variation between variation between the offspring of the offspring of one set of one set of parents.parents.


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22. Some variations are . Some variations are favorable. favorable.

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33. More offspring are . More offspring are produced than can produced than can survive.survive.

Overproduction of Overproduction of offspringoffspring

When there are too many offspring When there are too many offspring for an environment to support…for an environment to support…

There will be competition for There will be competition for resources.resources.


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44. Those that survive . Those that survive have favorable traits.have favorable traits.

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55. A population will . A population will change over time.change over time.

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Natural Selection VideoNatural Selection Video


PRACTICE WORKSHEETPRACTICE WORKSHEETExample: WormsExample: Worms

a.a.N.S. N.S. againstagainst: diurnal worms N.S. For: : diurnal worms N.S. For: nocturnalnocturnal worms worms

1.1.Some worms eat during the day; some at nightSome worms eat during the day; some at night

2.2.The ability to hide during the day keeps them saferThe ability to hide during the day keeps them safer

3.3.They have 500 babies, but only 100 surviveThey have 500 babies, but only 100 survive

4.4.The babies will be nocturnalThe babies will be nocturnal

5.5.Over time, the nocturnal worms will survive more than Over time, the nocturnal worms will survive more than the diurnal worms.the diurnal worms.


Key IdeasKey Ideas

1. 1. Struggle for ExistenceStruggle for Existence

2.2. Survival of the FittestSurvival of the Fittest

3.3. Natural SelectionNatural Selection

4.4. Descent with ModificationDescent with Modification


#4#4

Descent with Descent with ModificationModification

Every living Every living species has species has

descended, with descended, with changes, from changes, from

other species, other species, over over timetime


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Descent With Descent With ModificationModification

Species Species Today Look Different From Their From Their AncestorsAncestors

Happened overHappened over

long periods long periods ofof

timetime

Descent With Descent With ModificationModification

Descent With Modification

Implies that all living organisms are related to one another

If we look far enough back, we could find the common ancestor of all living things.

Two levelsTwo levels

A. SpeciationA. Speciation


SpeciationSpeciation

SpeciationSpeciation: the process of new : the process of new species forming.species forming.


Two levelsTwo levels

B. All organismsB. All organisms


Tree of LifeTree of Life


Tree of Life WorksheetTree of Life Worksheet


QuestionsQuestionsPlease mark with a colored pencil.Please mark with a colored pencil.

1.1. Where is the beginning of time?Where is the beginning of time?

2.2. Where is today?Where is today?

3.3. Which branch represents bacteria?Which branch represents bacteria?

4.4. Where do eukaryotes start?Where do eukaryotes start?

5.5. Where does photosynthesis start?Where does photosynthesis start?

6.6. There are 7 main branches. Which There are 7 main branches. Which one represents animals?one represents animals?

7.7. Where would humans be?Where would humans be?copyright cmassengale 74

ClosureClosure

Sum up Sum up ““Descent Descent with modificationwith modification”” in your own words.in your own words.


Tree of Life

Summary of Darwin’s Ideas

#1 The Struggle for Existence#2 Survival of the Fittest#3 Natural Selection#4 Descent with Modification

Evolution

Technology

darwins theory of evolution

history of evolution

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