Theoryofevolution 110815170612-phpapp01

Theory of EvolutionTheory of EvolutionBy Nonhlanhla NkosiBy Nonhlanhla Nkosi

DefinitiDefinitionon

•Evolution is the slow , gradual change in a population of organisms over time

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Isn’t evolution “just a theory”?In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence.

The formal scientific definition of “theory” is quite different from the every day meaning.

It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.http://evolution.berkeley.edu/evosite/evohome.htm

EvolutionEvolutionPre-Darwin BeliefsPre-Darwin Beliefs

•Earth was only a few thousand years Earth was only a few thousand years old. old.

•We now knowWe now know it is billions of years it is billions of years old.old.

•Neither the planet nor the species Neither the planet nor the species that inhabited it had changed since that inhabited it had changed since the beginning of time. the beginning of time.

•We now knowWe now know the planet has changed the planet has changed and, through fossils, discovered and, through fossils, discovered organisms have changed, as well.organisms have changed, as well.

THE THEORY OF EVOLUTIONTHE THEORY OF EVOLUTION

• CHARLES DARWINCHARLES DARWIN

• EVIDENCE FOR EVOLUTIONEVIDENCE FOR EVOLUTION

• MECHANISMS FOR EVOLUTIONMECHANISMS FOR EVOLUTION

• NATURAL SELECTIONNATURAL SELECTION

• SPECIATIONSPECIATION

Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

http://evolution.berkeley.edu/evolibrary/home.php

Charles Darwin Charles Darwin the Naturalistthe Naturalist

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Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.http://evolution.berkeley.edu/evolibrary/home.php

Voyage of the BeagleVoyage of the BeagleCharles DarwinCharles Darwin

• Born Feb. 12, 1809Born Feb. 12, 1809

• Joined Crew of HMS Joined Crew of HMS Beagle, 1831Beagle, 1831

• NaturalistNaturalist

• 5 Year Voyage around 5 Year Voyage around worldworld

• Avid Collector of Avid Collector of Flora & FaunaFlora & Fauna

• Astounded By Variety Astounded By Variety of Lifeof Life

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Darwin Left England in Darwin Left England in 18311831

99Darwin returned 5 years later in 1836Darwin returned 5 years later in 1836

EVIDENCE OF EVOLUTIONEVIDENCE OF EVOLUTION• STRUCTURAL ADAPTATIONSSTRUCTURAL ADAPTATIONS• MIMICRY – the insect looks like the leafMIMICRY – the insect looks like the leaf• CAMOUFLAGE – the chameleon can change CAMOUFLAGE – the chameleon can change color to match its surroundingscolor to match its surroundings


http://evolution.berkeley.edu/evolibrary/home.phphttp://science.howstuffworks.com/animal-camouflage2.htm

EVIDENCE OF EVOLUTIONEVIDENCE OF EVOLUTION• STRUCTURAL ADAPTATIONSSTRUCTURAL ADAPTATIONS• MIMICRYMIMICRY• CAMOUFLAGECAMOUFLAGE• MILLIONS OF YEARSMILLIONS OF YEARS

• PHYSIOLOGICAL ADAPTATIONSPHYSIOLOGICAL ADAPTATIONS• CHANGE IN A METABOLIC PROCESSCHANGE IN A METABOLIC PROCESS• WHAT DO YOU HEAR ABOUT IN THE NEWS WHAT DO YOU HEAR ABOUT IN THE NEWS ABOUT SOME BACTERIA?ABOUT SOME BACTERIA?


The Galapagos The Galapagos IslandsIslands

• Small Group of Islands 1000 km West of Small Group of Islands 1000 km West of South AmericaSouth America

•Very Different ClimatesVery Different Climates

•Animals On Islands UniqueAnimals On Islands Unique•TortoisesTortoises•IguanasIguanas•FinchesFinches

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• Volcanic islandsVolcanic islands off off the coast of South the coast of South AmericaAmerica

• Island species Island species varied from mainland varied from mainland species & from species & from island-to-island island-to-island speciesspecies

• Each island had long Each island had long or short neck or short neck tortoisestortoises

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• Finches on the islands Finches on the islands resembled a resembled a mainland finchmainland finch

• More types of finches appeared on the More types of finches appeared on the islandsislands where the available food was where the available food was different (seeds, nuts, berries, different (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

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Darwin’s Darwin’s ObservationsObservations

• Patterns of Patterns of Diversity were Diversity were shownshown

• Unique Unique Adaptations in Adaptations in organismsorganisms

• Species Not Species Not Evenly Evenly DistributedDistributed• Australia, Kangaroos, Australia, Kangaroos, but No Rabbitsbut No Rabbits

• S. America, LlamasS. America, Llamas

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•Both Living Both Living Organisms & Organisms & Fossils Fossils collectedcollected

•Fossils Fossils included:included:•TrilobitesTrilobites•Giant Ground Giant Ground Sloth of Sloth of South AmericaSouth America

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This species NO longer existed.This species NO longer existed.

What had happened to them?What had happened to them?

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Evidence for Evolution – The Fossil RecordEvidence for Evolution – The Fossil Record


• Left unchecked, the number of organisms of each species will increase exponentially, generation to generation

• In nature, populations tend to remain stable in size

• Environmental resources are limited

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• Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike.

• Much of this variation between individuals is inheritable.

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Darwin’s ConclusionDarwin’s Conclusion• Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals

• Only a fraction of offspring survive each generation

• Survival of the Fittest

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Darwin’s ConclusionDarwin’s Conclusion

• Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals

• Called Natural Selection

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OTHER EVIDENCE OF EVOLUTIONOTHER EVIDENCE OF EVOLUTION

• FOSSILSFOSSILS

• ANATOMYANATOMY• HOMOLOGOUS STRUCTURES – structures that HOMOLOGOUS STRUCTURES – structures that are similar because they are inherited are similar because they are inherited from a common ancestor from a common ancestor




• FOSSILSFOSSILS

• ANATOMYANATOMY• HOMOLOGOUS STRUCTURESHOMOLOGOUS STRUCTURES• ANALOGOUS STRUCTURES – structures that are similar ANALOGOUS STRUCTURES – structures that are similar

because they serve the same function but do not have because they serve the same function but do not have a common ancestor.a common ancestor.



OTHER EVIDENCE OF EVOLUTIONOTHER EVIDENCE OF EVOLUTION• FOSSILSFOSSILS

• ANATOMYANATOMY• HOMOLOGOUS STRUCTURESHOMOLOGOUS STRUCTURES• ANALOGOUS STRUCTURESANALOGOUS STRUCTURES• VESTIGIAL STRUCTURE – a feature inherited from an VESTIGIAL STRUCTURE – a feature inherited from an ancestor that is now less elaborate and ancestor that is now less elaborate and functional, usually formed when a population functional, usually formed when a population experiences a different environmentexperiences a different environment

WHAT IS ANOTHER EXAMPLE OF VESTIGIAL STRUCTURES?



These fish live in the dark and therefore do not need functional eyes.


• FOSSILSFOSSILS

• ANATOMYANATOMY• HOMOLOGOUS STRUCTURESHOMOLOGOUS STRUCTURES• ANALOGOUS STRUCTURESANALOGOUS STRUCTURES• VESTIGIAL STRUCTUREVESTIGIAL STRUCTURE• EMBRYOSEMBRYOS


Similarities In Similarities In Early DevelopmentEarly Development

• Embryonic Structures Of Different Embryonic Structures Of Different Species Show Significant SimilaritiesSpecies Show Significant Similarities

• EmbryoEmbryo – early stages of vertebrate – early stages of vertebrate developmentdevelopment

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Human Fetus – 5 Human Fetus – 5 weeksweeks

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Chicken Turtle

Rat

MECHANISMS FOR EVOLUTIONMECHANISMS FOR EVOLUTION

• DO POPULATIONS OR INDIVIDUALS EVOLVE?DO POPULATIONS OR INDIVIDUALS EVOLVE?

• WHAT IS A GENE POOL?WHAT IS A GENE POOL?

• HOW CAN THE GENE POOL CHANGE?HOW CAN THE GENE POOL CHANGE?• MUTATIONMUTATION• GENETIC DRIFTGENETIC DRIFT• GENE FLOWGENE FLOW

• WOULD THESE THINGS EFFECT A LARGE POPULATION WOULD THESE THINGS EFFECT A LARGE POPULATION OR A SMALL POPULATION MORE?OR A SMALL POPULATION MORE?


Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.ALL IMAGES: http://evolution.berkeley.edu/evolibrary/home.php

Any change in an organism’s DNA

When some organisms RANDOMLY survive longer than others and pass on their genes.

The movement of genes from one population to another through migration of individuals.









WHAT IS NATURAL SELECTION?WHAT IS NATURAL SELECTION?


Variation in some traits (color of beetles)

Green beetles tend to get eaten and do not survive long enough to reproduce

The surviving brown beetles have brown offspring.

Eventually all the green beetles get eaten, leaving only brown beetles.

Darwin’s Theory Darwin’s Theory of Evolutionof Evolution

Organisms Change Over TimeOrganisms Change Over Time

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Common Descent with Common Descent with ModificationModification

• Darwin proposed Darwin proposed that organisms that organisms descended from descended from common ancestorscommon ancestors

• Idea that Idea that organisms organisms change change with timewith time, , diverging from a diverging from a common formcommon form

• Caused Caused evolution evolution of new speciesof new species

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Natural SelectionNatural Selection

• The Struggle for ExistenceThe Struggle for Existence (compete for (compete for food, mates, space, water, etc.)food, mates, space, water, etc.)

• Survival of the FittestSurvival of the Fittest (strongest able (strongest able to survive and reproduce)to survive and reproduce)

• Descent with Modification Descent with Modification (new species (new species arise from common ancestor replacing arise from common ancestor replacing less fit species)less fit species)

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Natural selectionNatural selection

• Fitness• Ability of an Individual Ability of an Individual

To Survive & ReproduceTo Survive & Reproduce

• Adaptation• Inherited Characteristic Inherited Characteristic

That Increases an That Increases an Organisms Chance for Organisms Chance for SurvivalSurvival

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•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.

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Survival of the Survival of the FittestFittest

•Fitness Is Central To The Is Central To The Process Of EvolutionProcess Of Evolution

•Individuals With Low FitnessIndividuals With Low Fitness• DieDie• Produce Few OffspringProduce Few Offspring

Survival of the Fittest

AKA AKA Natural Selection

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Key ConceptOver Time, Natural Over Time, Natural Selection Results In Selection Results In Changes In The Inherited Changes In The Inherited Characteristics Of A Characteristics Of A Population. These Changes Population. These Changes Increase A Species Increase A Species Fitness In Its Fitness In Its EnvironmentEnvironment

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•POPULATIONS evolve NOT INDIVIDUALS.

•NATURAL SELECTION only works on heritable traits.

•A trait that is favorable in oneenvironment may be useless or detrimental in another.

IMPORTANT TO REMEMBER !









WHAT IS SPECIATION?WHAT IS SPECIATION?

• GEOGRAPHIC ISOLATIONGEOGRAPHIC ISOLATION



A barrier, either physical, like a river changing course, or nonphysical, causes the population to become separated.



• REPRODUCTIVE REPRODUCTIVE ISOLATIONISOLATION• for example, what for example, what might occur between might occur between fruit flies raised fruit flies raised on different types on different types of food? of food?

• when allowed to when allowed to interact, some would interact, some would only mate with the only mate with the same food preference same food preference as itselfas itself



BOTH LIVE IN FOREST ECOSYSTEMSBOTH LIVE IN FOREST ECOSYSTEMS

Adapted to similar environments, but evolved independently from different ancestors.

SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North American FLYING SQUIRRELS becauseits ancestors were marsupials.



• REPRODUCTIVE ISOLATIONREPRODUCTIVE ISOLATION

• PACE OF EVOLUTION: PACE OF EVOLUTION:


Gradualism – slow steady change over a long time

Punctuated equilibrium – a large amount of change in a short time due to a specific event.



• REPRODUCTIVE ISOLATIONREPRODUCTIVE ISOLATION

• GRADUALISMGRADUALISM

• PUNCTUATED EQUILIBRIUMPUNCTUATED EQUILIBRIUM

• DIVERGENT EVOLUTION – two species that are DIVERGENT EVOLUTION – two species that are now dissimilar but can be traced back to now dissimilar but can be traced back to the same ancestorthe same ancestor• ADAPTIVE RADIATION – adaptations to survive in ADAPTIVE RADIATION – adaptations to survive in

new environmental conditionsnew environmental conditions

• CONVERGENT EVOLUTION – species having CONVERGENT EVOLUTION – species having similar features in spite of not having the similar features in spite of not having the same ancestorsame ancestor


ADAPTIVE RADIATION – AN EXAMPLE ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTIONOF DIVERGENT EVOLUTION



http://www.vanderbilt.edu/AnS/english/Clayton/Galapago_finches.gif

CONVERGENT EVOLUTION –EXAMPLECONVERGENT EVOLUTION –EXAMPLE



Evolutionary Evolutionary TimelineTimeline

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Lamarck’s Theory of Lamarck’s Theory of EvolutionEvolution

• Jean-Baptiste LamarckJean-Baptiste Lamarck, , 18091809

• One Of First Scientists One Of First Scientists To Understand That To Understand That Change Occurs Over TimeChange Occurs Over Time

• Stated that Changes Are Stated that Changes Are Adaptations To Adaptations To Environment Environment acquired in acquired in an organism’s lifetimean organism’s lifetime

• Said acquired changes Said acquired changes were passed to were passed to offspringoffspring

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• Idea called Idea called Law of Law of Use and DisuseUse and Disuse

• If a body part If a body part were used, it got were used, it got strongerstronger

• If body part NOT If body part NOT used, it used, it deteriorateddeteriorated

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•Inheritance of Acquired Inheritance of Acquired CharacteristicsCharacteristics

• Proposed That By Selective Use Or Proposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their Or Lost Certain Traits During Their LifetimeLifetime

• These These Traits Could Then Be Passed On Traits Could Then Be Passed On To Their OffspringTo Their Offspring

• Over Time This Led To Over Time This Led To New SpeciesNew Species

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• Use & Disuse - Use & Disuse - Organisms Could Organisms Could Change The Size Or Change The Size Or Shape Of Organs By Shape Of Organs By Using Them Or Not Using Them Or Not Using ThemUsing Them

• Blacksmiths & Their SonsBlacksmiths & Their Sons (muscular arms)(muscular arms)

• Giraffe’s Necks LongerGiraffe’s Necks Longer from stretching)from stretching)

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The male fiddler crab uses itsfront claw to attract mates andward off predators.

“USE or DISUSE” = Use it or lose it

Through repeated use, the frontclaw becomes larger.

The fiddler passes on this acquired characteristic to its offspring

INHERITANCE OF ACQUIRED CHARACTERISTICS

What’s wrong with Lamarck’s What’s wrong with Lamarck’s hypothesis?hypothesis?Lamarck didn’t know aboutLamarck didn’t know about

genes and how traits are genes and how traits are inherited.inherited.

Acquired traits are not passed on Acquired traits are not passed on to offspringto offspring

Or are they? . . . New field of EPIGENETICS is exploring this

http://www.geocities.com/arnold_schwarzenegger_pictures/


• Inheritance Of Acquired TraitsInheritance Of Acquired Traits• Traits Acquired During Ones Lifetime Traits Acquired During Ones Lifetime Would Be Passed To OffspringWould Be Passed To Offspring

5959Clipped ears of dogs could be passed to offspring!

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

• Darwin Knew That His Theory Would Be Darwin Knew That His Theory Would Be Extremely ControversialExtremely Controversial And Would Be And Would Be AttackedAttacked

• His Theory His Theory Challenged Established Challenged Established Religious & Scientific BeliefsReligious & Scientific Beliefs, , Particularly About The Creation Of ManParticularly About The Creation Of Man

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• He Refused To Publish He Refused To Publish Until He Received An Until He Received An Essay From Essay From Alfred Alfred WallaceWallace• Fellow NaturalistFellow Naturalist• Independently Developed The Independently Developed The Same TheorySame Theory

• After 25 Years, Someone After 25 Years, Someone Else Had Come To The Same Else Had Come To The Same Conclusions From Their Conclusions From Their Observations Of NatureObservations Of Nature

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Wallace’s Wallace’s ContributionContribution

• Alfred Russel WallaceAlfred Russel Wallace Independently came to Independently came to same Conclusion as same Conclusion as Darwin that species Darwin that species changed over time changed over time because of their because of their struggle for struggle for existenceexistence

• When Darwin read When Darwin read Wallace’s essay, Wallace’s essay, he he knew he had to knew he had to publish his findingspublish his findings

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• Darwin Presented Wallace’s Essay & Darwin Presented Wallace’s Essay & Some Of His Work At A Scientific Some Of His Work At A Scientific Conference of the Conference of the Linnaean SocietyLinnaean Society in in July of July of 18581858

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

• It Took Darwin 18 Months To Complete It Took Darwin 18 Months To Complete The BookThe Book

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Natural Variation and Natural Variation and Artificial SelectionArtificial Selection

• Abandoned The IdeaAbandoned The Idea That Species Were That Species Were Perfect & UnchangingPerfect & Unchanging

• Observed Observed Significant Variation in All Significant Variation in All SpeciesSpecies Observed Observed

• Observed Observed Farmers Use VariationFarmers Use Variation To To Improve Crops & Livestock Improve Crops & Livestock

• Called Called Selective BreedingSelective Breeding

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•Natural VariationNatural Variation•Differences Among Differences Among Individuals Of A SpeciesIndividuals Of A Species

•Artificial SelectionArtificial Selection•Selective Breeding To Selective Breeding To Enhance Desired Traits Among Enhance Desired Traits Among Stock or CropsStock or Crops

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Key Concept:Key Concept:In In Artificial SelectionArtificial Selection,, Nature Provided The Nature Provided The Variation Among Different Variation Among Different Organisms, And Humans Organisms, And Humans Selected Those Variations Selected Those Variations That They Found UsefulThat They Found Useful

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Slide by Kim Foglia@ http://www.explorebiology.com/

EX: Changes in disease-causing microbes that produce new organisms and new diseases.

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http://www.hipusa.com/eTools/webmd/A-Z_Encyclopedia/tuberculosis.jpg

http://www.hhmi.org/askascientist/images/hiv.gif

Can see Natural selection happen

Bird flu

Antibiotic-resistant tuberculosis

HIV

Why does evolution matter now?

Mutation, Evolution, and Mutation, Evolution, and Natural SelectionNatural Selection

• Http://www.youtube.com/watch?v=ZK6YP1Smbxk Http://www.youtube.com/watch?v=ZK6YP1Smbxk

DNA is found in the nucleus of the cell

Mutation Mutation • A mutation is a change in gene sequence.A mutation is a change in gene sequence.

• There are many different types of mutations and causes for There are many different types of mutations and causes for them.them.

• Some mutations are harmful, while others can be beneficial.Some mutations are harmful, while others can be beneficial.

HarmfuHarmfull

Beneficial

How does mutations How does mutations work?work?

• DNA is very accurate when making copies of itself, however, sometimes DNA is very accurate when making copies of itself, however, sometimes it makes a mistake.it makes a mistake.

• Here’s a DNA sequenceHere’s a DNA sequence

• AGCCCTTATAGGCTCAGCCCTTATAGGCTC

• What are the corresponding base pairs?What are the corresponding base pairs?

• TCGGGAATATCCGAGTCGGGAATATCCGAG

• Now when it’s being copied it replaces the T with a U. Rewrite the your Now when it’s being copied it replaces the T with a U. Rewrite the your answer with U’s instead of T’s.answer with U’s instead of T’s.

• UCGGGAAUAUCCGAGUCGGGAAUAUCCGAG

• What amino acids will this be coded for?What amino acids will this be coded for?

• Serine, Glycine, Isoleucine, Serine, Glutamic Acid Serine, Glycine, Isoleucine, Serine, Glutamic Acid

The Mutation The Mutation • Here’s our original DNA sequenceHere’s our original DNA sequence

• AGCCCTTATAGGCTCAGCCCTTATAGGCTC

• AATTCCCTTATAGGCTC we replaced the G with a TCCCTTATAGGCTC we replaced the G with a T

• Now what are the corresponding base pairs?Now what are the corresponding base pairs?

• TTAAGGGAATATCCGAGGGGAATATCCGAG

• Now when it’s being copied it replaces the T with a U. Now when it’s being copied it replaces the T with a U. Rewrite the your answer with U’s instead of T’s.Rewrite the your answer with U’s instead of T’s.

• UUAAGGGAAUAUCCGAGGGGAAUAUCCGAG

• What amino acids will this be coded for?What amino acids will this be coded for?

• StopStop, Glycine, Isoleucine, Serine, Glutamic Acid , Glycine, Isoleucine, Serine, Glutamic Acid

• You can see how replacing 1 base will change everything!You can see how replacing 1 base will change everything!

References References

• This is a mash up of 5 different sources which are:This is a mash up of 5 different sources which are:

• Allen, A. (2011). Allen, A. (2011). Theory of Evolution. Theory of Evolution. http://www.slideshare.net/MsAllenBio/theory-of-evolution-http://www.slideshare.net/MsAllenBio/theory-of-evolution-88586758858675

• Zolli. (2012). Zolli. (2012). Evolution and Natural selection- How species Evolution and Natural selection- How species change over timechange over time. . http://www.slideshare.net/mrzolli/evolution-and-natural-http://www.slideshare.net/mrzolli/evolution-and-natural-selection-powerpointselection-powerpoint

• Tas11244. (2011). Tas11244. (2011). Evolution: diversity of lifeEvolution: diversity of life. . http://www.slideshare.net/tas11244/darwin-evolution-revised-http://www.slideshare.net/tas11244/darwin-evolution-revised-with-turning-point-qswith-turning-point-qs

• Cinhasler. (2011). Cinhasler. (2011). Descent with modification- a Darwanian Descent with modification- a Darwanian view of life. view of life. http://www.slideshare.net/cinhasler/a-pch22http://www.slideshare.net/cinhasler/a-pch22

• Highland. N. (2010Highland. N. (2010). Mutation, Evolution and natural ). Mutation, Evolution and natural selectionselection. http://www.slideshare.net/ismscience/mutation-. http://www.slideshare.net/ismscience/mutation-evolution-and-natural-selection evolution-and-natural-selection

Education

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