Chapter 15. Chapter 15. Natural Natural

Selection an & Selection an & The Evidence The Evidence

for Evolutionfor Evolution The theory The theory

& & Supporting Supporting EvidenceEvidence

Chapter 15: Learning ObjectivesChapter 15: Learning Objectives

Be able to summarize Darwin’s Theory of EvolutionBe able to summarize Darwin’s Theory of Evolution Be able to explain how Structural Adaptations relate to natural Be able to explain how Structural Adaptations relate to natural

selection and use examples.selection and use examples. How do mimicry and camouflage help species survive?How do mimicry and camouflage help species survive? Be able to explain how Physiological Adaptations relate to natural Be able to explain how Physiological Adaptations relate to natural

selection and use examples.selection and use examples. Distinguish among the types Distinguish among the types of evidenceof evidence for evolution; be able to for evolution; be able to

explain how these demonstrate evolutionary relationships.explain how these demonstrate evolutionary relationships. Fossils, Anatomy, Embryology, BiochemistryFossils, Anatomy, Embryology, Biochemistry Be able to distinguish between Homologous, Analagous and Vestigal Be able to distinguish between Homologous, Analagous and Vestigal

StructuresStructures How do vertebrate embryos indicate common ancestry?How do vertebrate embryos indicate common ancestry?

Distinguish between the ways that Natural Selection acts on variations Distinguish between the ways that Natural Selection acts on variations within populations.within populations.

Stabilizing Selection, Directional Selection, Disruptive SelectionStabilizing Selection, Directional Selection, Disruptive Selection Be able to define Species and the basis for speciation.Be able to define Species and the basis for speciation. How do geographic barriers contribute to speciation?How do geographic barriers contribute to speciation? Be able to describe the two theories on the Rate of Speciation, and how Be able to describe the two theories on the Rate of Speciation, and how

they differ; similar.they differ; similar. Be able to describe Be able to describe Adaptive radiation and Convergent EvolutionAdaptive radiation and Convergent Evolution

Evolution videosEvolution videos

Evolution Videos for Students EvolvinEvolution Videos for Students Evolving g Ideas.mhtIdeas.mht (6 evolution video clips) (6 evolution video clips)

Assignment: Due Monday, April 7thAssignment: Due Monday, April 7thRead Chapter 15, and answer do the following. May Read Chapter 15, and answer do the following. May

(encouraged to) use other sources as well. Be prepared to (encouraged to) use other sources as well. Be prepared to explain your work in class.explain your work in class.

Directions: Prepare a booklet ( may use a Directions: Prepare a booklet ( may use a foldable style such as we used for Biomes) foldable style such as we used for Biomes) which contains the following:which contains the following:

Description of Darwin’s Theory Of Evolution and the Description of Darwin’s Theory Of Evolution and the process of Natural Selection.process of Natural Selection.

List the steps involved in the process of Natural List the steps involved in the process of Natural Selection and new species formation (see Fig. 15.2)Selection and new species formation (see Fig. 15.2)

Define, describe, illustrate the following terms :Define, describe, illustrate the following terms : Homologous StructuresHomologous Structures Analagous Structures ( 1 plant, 1 animal)Analagous Structures ( 1 plant, 1 animal) Vestigal StructuresVestigal Structures Geographic Isolation –associated with SpeciationGeographic Isolation –associated with Speciation

( be sure to include …)( be sure to include …)*Definition of term*Definition of term*Pictures (2 for each—hand drawn or copied and colored) to *Pictures (2 for each—hand drawn or copied and colored) to

illustrate the term.illustrate the term.*Explanation of why your pictures demonstrate the terms. *Explanation of why your pictures demonstrate the terms.

EVOLUTIONEVOLUTION

EvolutionEvolution: : Heritable Heritable change in a species change in a species over time.over time.

Theories of Evolution-Theories of Evolution-attempt to explain attempt to explain diversity of life on diversity of life on

earthearth Prior to 1800’s: : Prior to 1800’s: : CreationismCreationism

Beginning around 1800::Beginning around 1800::Scientists attempt to Scientists attempt to come to terms with come to terms with growing fossil evidence.growing fossil evidence.

Newer Theories of Newer Theories of EvolutionEvolution

1. 1. De Buffon(1707-1788):De Buffon(1707-1788): Life and Life and Earth have a history: Earth have a history: Life not Life not fixed since Creation.(fixed since Creation.(very very radical). Life evolves. Vestigal radical). Life evolves. Vestigal structures.structures.

2.George S. 2.George S. Cuvier ( 1769-1832)Cuvier ( 1769-1832): : Theory of Catastrophism: Theory of Catastrophism: Species Species were fixed & unchangingwere fixed & unchanging. . Mass extinctions ; other species Mass extinctions ; other species migrate to fill in open niche.migrate to fill in open niche.

3. 3. Jean Jean LamarckLamarck (1744-1829): (1744-1829): Life evolvesLife evolves

Change through Change through use and use and disusedisuse. Evolution due to . Evolution due to inheritance ofinheritance of acquired acquired characteristics.characteristics.

..4. Charles 4. Charles Darwin (1809-1882):Darwin (1809-1882): Life evolves. Life evolves. Species change over time by Species change over time by

way of way of Natural SelectionNatural Selection

******Charles DarwinCharles Darwin****** Left Med.School; Degree in Theology; Left Med.School; Degree in Theology;

Avid interest in natureAvid interest in nature HMS BeagleHMS Beagle to South America & to South America &

Galapagos Islands- 5 year charting Galapagos Islands- 5 year charting voyage- (1831-1836)voyage- (1831-1836)

Ship’s Naturalist- collect & catalog Ship’s Naturalist- collect & catalog flora & faunaflora & fauna

His observations profoundly change His observations profoundly change his beliefshis beliefs

Voyage of the H.M.S. Voyage of the H.M.S. Beagle-Beagle-

Charles DarwinCharles Darwin 1859 wrote1859 wrote The Origin Of Species by Means of The Origin Of Species by Means of

Natural SelectionNatural SelectionControversialControversial: :

He suggested:He suggested:

Apes apes and humans have common Apes apes and humans have common ancestry.ancestry.

Species change New SpeciesSpecies change New Species

Presented evidencePresented evidence that evolution occurred that evolution occurred Proposed mechanismProposed mechanism for evolution— for evolution—Natural Natural

SelectionSelection

Darwin’s Observations Darwin’s Observations Provided The Provided The EvidenceEvidence

andand Mechanism Mechanism for for

EvolutionEvolution

GALAPAGOS GALAPAGOS TOTOISESTOTOISES

Species Species uniqueunique to the to the islands, but islands, but similar to similar to those observed on those observed on the s. American the s. American mainlandmainland..

Figure 22.1

Marine Iguanas-nowhere else on Earth-swim, cling to rocks

eating moss

Blue-footed boobies-Blue-footed boobies-adaptations of other kinds—adaptations of other kinds—

attract matesattract mates

Galápagos FinchesGalápagos Finches Beak Beak

shape shape varies varies with with dietdiet

Berry

eater

Insect eaters

Insect eaters

Cactus eaters

Seed eaters

1.Found on all islands-1.Found on all islands-butbut

slightslight variances between variances between themthem. . Different beaks.Different beaks.

2. 2. SSimilar to those on imilar to those on South America mainland.South America mainland.

His Finch ObservationsHis Finch Observations

Explaining his Explaining his observationsobservations

1. A few organisms migrated1. A few organisms migrated From S. AmericaFrom S. America Populated all 13 islandsPopulated all 13 islands

2. Variations existed among them.2. Variations existed among them.

3.Individuals with useful variations 3.Individuals with useful variations passed these along to the next passed these along to the next generation.generation.

4. Over time offspring with certain 4. Over time offspring with certain variations make up most of the variations make up most of the populationpopulation

Conditions varied island to Conditions varied island to island, so finches varied by island, so finches varied by habitat.habitat.

5.Many new species formed from 5.Many new species formed from these original ancestors.these original ancestors.

The process of Natural The process of Natural Selection—Steps Darwin Selection—Steps Darwin

proposes.proposes. 1. Organisms produce 1. Organisms produce moremore

________than can survive________than can survive 2. Competition/2. Competition/________ for ________ for

ExistenceExistence-compete for food, -compete for food, living space;living space;

3. Only 3. Only somesome can can ______ ______ and and

reproducereproduce..

4. Those with useful _________ 4. Those with useful _________ survive in their environment, survive in their environment, pass those traits on to pass those traits on to _____________._____________.

5. Over time, their traits 5. Over time, their traits become more __________ in the become more __________ in the population.population.

Evolution videoEvolution video

Evolution Videos for Students EvolvinEvolution Videos for Students Evolving g Ideas.mhtIdeas.mht (hummingbird evolution) (hummingbird evolution)

The Mechanism: The Mechanism: HowHow evolution happens… evolution happens…

Natural selectionNatural selection : Organisms : Organisms with _______ (Adaptations) well with _______ (Adaptations) well suited to an _________ are more suited to an _________ are more likely to survive and produce likely to survive and produce more offspring than organisms more offspring than organisms without these favorable traits. without these favorable traits. Only the fittest will survive!!!---Only the fittest will survive!!!---

To Summarize To Summarize DarwinDarwin

Species change over Species change over time and give rise to time and give rise to new species through new species through the process of natural the process of natural selection (survival of selection (survival of the ___________).the ___________).

ADAPTATIONS-evidence ADAPTATIONS-evidence for evolution.for evolution.

..

Darwin clearly understood a fundamental principle of Darwin clearly understood a fundamental principle of

evolution—that ____________, not individuals, evolution—that ____________, not individuals, evolve and become adapted to the evolve and become adapted to the environments in which they live.environments in which they live.The term “adaptation” has _____ meanings in The term “adaptation” has _____ meanings in evolutionary biology.evolutionary biology.

The first meaning refers to the processes by which The first meaning refers to the processes by which adaptive traits are acquired. adaptive traits are acquired.

The second meaning refers to the traits that enhance The second meaning refers to the traits that enhance the survival and reproductive success of their the survival and reproductive success of their bearers. bearers.

AdaptationsAdaptations: : Structural or Physiological Structural or Physiological

AdaptationsAdaptations : any variation that : any variation that aids an organisms chances for aids an organisms chances for ____________ in its ________________.____________ in its ________________.

Arise over time-many ___________.Arise over time-many ___________.

Kinds of AdaptationsKinds of Adaptations

1. ________-develop over millions of 1. ________-develop over millions of yearsyears

2. ____________-can occur much more 2. ____________-can occur much more rapidly.rapidly.

1. Structural Adaptations1. Structural Adaptations1. Defense: some defense mechanisms1. Defense: some defense mechanisms

claws, teethclaws, teeth

2. Protective :2. Protective :a) Mimicrya) Mimicry-one organism _____________ -one organism _____________ anotheranother

b) Camouflageb) Camouflage-__________ into the surroundings-__________ into the surroundingsc) Warning colorationc) Warning coloration

ColorationColoration

CConspicuous onspicuous colors --colors -- warn warn off predators.off predators.

poison arrow frogspoison arrow frogs

MimicryMimicry Look alikesLook alikes

Hawk moth larva Snake

MimicryMimicry

Cuckoo Bee Yellow Jacket

mimicrymimicry

CamouflageCamouflage A ________ defense where the prey A ________ defense where the prey

is camouflaged against its is camouflaged against its environment.environment.

peacocks peacocks evolevol video.htmvideo.htm

2. Physiological 2. Physiological AdaptationsAdaptations

Changes in an organism’s _______________ Changes in an organism’s _______________ processes.processes.

These can develop rapidlyThese can develop rapidly Develop by natural selectionDevelop by natural selection

Examples:Examples: Bacteria-resistance to _______________Bacteria-resistance to _______________ Weeds—resistance to herbicidesWeeds—resistance to herbicides Insects-resistance to ________________Insects-resistance to ________________

Other evidence for Other evidence for Evolution- Evolution-

Most evidence for evolution is ___________.Most evidence for evolution is ___________. FossilsFossils Comparative AnatomyComparative Anatomy Comparative DevelopmentComparative Development Comparative BiochemistryComparative Biochemistry

Compare Development/EmbryologyCompare Development/Embryology

Biochemistry Biochemistry

1. FOSSILS1. FOSSILS

Can help to demonstrateCan help to demonstrate evolutionary pathevolutionary path

SinornithosaurusSinornithosaurus Feathered Dinosaur: Missing Link Feathered Dinosaur: Missing Link

between Birds and dinosaursbetween Birds and dinosaurs

Anatomical Anatomical StructuresStructures

Homologous StructuresHomologous Structures

2. Homologous Structures2. Homologous Structures

Structural features that Structural features that are similar in arrangement, are similar in arrangement, in function or both due in function or both due to_______ _________to_______ _________

For example: For example: whale forelimb, whale forelimb, crockodile forelimb, bird crockodile forelimb, bird wing;wing;

Homologous StructuresHomologous Structures

..

VESTIGAL STRUCTURESVESTIGAL STRUCTURES——A body A body structure that no longer serves its structure that no longer serves its

original purpose;original purpose;remnants of evolutionary past--remnants of evolutionary past--

whale’s pelvis bonewhale’s pelvis bone ..

Vestigial StructuresVestigial Structures

Ancestral dogs Ancestral dogs had five toes had five toes on each footon each foot

As they evolved they became toe-walkers with As they evolved they became toe-walkers with only four toes on the ground only four toes on the ground

Big toes and thumbs were lost or reduced to Big toes and thumbs were lost or reduced to their present statetheir present state

Why do dogs have tiny, functionless Why do dogs have tiny, functionless toes on their feet (dewclaws)?toes on their feet (dewclaws)?

Normally a horse’s Normally a horse’s back foot has only back foot has only one functional toe, one functional toe, the thirdthe third

Remnants of Toes in Remnants of Toes in HorsesHorses

Splints are small Splints are small remnants of toes 2 and remnants of toes 2 and 4 that remain as 4 that remain as vestigesvestiges

More vestigal structuresMore vestigal structures

Vestigal structuresVestigal structures

'Whale Evolution' by PBS - 'Whale Evolution' by PBS - RichardDawkins_net.mhtRichardDawkins_net.mht

Analogous StructuresAnalogous Structures

Similar in function, but Similar in function, but not structure.not structure.

Why?? --do not have Why?? --do not have common ancestor (common ancestor (wings wings of bats and wings of of bats and wings of insectsinsects))

AnalogiesAnalogies: for example, plant adaptations: for example, plant adaptationsAdapted to similar _________pressures.Adapted to similar _________pressures.

The Process is called ____________evolution.The Process is called ____________evolution.

Analogous StructuresAnalogous Structuresexample:example:

EmbryologyEmbryology Embryo: earliest stages of ________ Embryo: earliest stages of ________

and ________ of both plants and and ________ of both plants and animals.animals.

All vertebrate embryos start out very All vertebrate embryos start out very similarlysimilarly Pharyngeal ___________Pharyngeal ___________ Postanal _________Postanal _________

Organisms evolve by adding stages to Organisms evolve by adding stages to their embryonic development,their embryonic development,

DEVELOPMENTALDEVELOPMENTAL PATTERNS PATTERNS

   ,,

Comparative Comparative Biochemistry Biochemistry

Compare ______ ______ sequenceCompare ______ ______ sequence Closely related species will show Closely related species will show

more similarities in the _____ ______ more similarities in the _____ ______ sequence that makes up the sequence that makes up the protein.protein.

Example: cytochrome c (table 15.2)Example: cytochrome c (table 15.2) Identical amino acids in chimpanzee proteinIdentical amino acids in chimpanzee protein

Chicken protein differs by 18 amino acidsChicken protein differs by 18 amino acids

Yeast protein differs by 56Yeast protein differs by 56

. . Despite its diet and its opposable thumb, Despite its diet and its opposable thumb,

the Giant Panda is a bear; and the Lesser the Giant Panda is a bear; and the Lesser Panda is closer to raccoons of N. America  Panda is closer to raccoons of N. America  

 

The Panda’s Thumb,Is it a The Panda’s Thumb,Is it a bear?bear?

Panda web Panda web pandafixpandafix Other Panda Other Panda

Video.mhtVideo.mht RedPandaClipFilmRedPandaClipFilm

clip - Red panda (subspecies clip - Red panda (subspecies styanistyani) feeding on bamboo, using modified ) feeding on bamboo, using modified wrist bone as sixth digit - Red panda wrist bone as sixth digit - Red panda sspssp_ - _ - AilurusAilurus fulgensfulgens styanistyani - - ARKive.mhtARKive.mht

.Giant .Giant PandaPanda

 

15.2 Mechanisms of 15.2 Mechanisms of EvolutionEvolution

Gene Pool: all of the ________ of the Gene Pool: all of the ________ of the population’s genes pooled together.population’s genes pooled together.

Allelic Frequency:Allelic Frequency:

Genetic Equilibrium:Genetic Equilibrium:

Natural Selection acts on Natural Selection acts on Variation: Genetic VariationVariation: Genetic Variation

Occurs in individuals in populations Occurs in individuals in populations of all species of all species Frequency can change within a Frequency can change within a

populationpopulation

(a) Map butterflies thatemerge in spring:orange and brown

(b) Map butterflies thatemerge in late summer:black and white

3 Modes of Selection3 Modes of Selection Directional SelectionDirectional Selection: Favors : Favors

_____ phenotypic extreme._____ phenotypic extreme. Can lead to rapid evolution.Can lead to rapid evolution. Disruptive SelectionDisruptive Selection::

Favors _____phenotypic extremes.Favors _____phenotypic extremes. Stabilizing SelectionStabilizing Selection: Favors : Favors

the ______phenotype; overall the ______phenotype; overall reducing variation.reducing variation.

MODES OF SELECTIONMODES OF SELECTION

DIRECTIONAL SELECTION-only one DIRECTIONAL SELECTION-only one selective force on an alleleselective force on an allele

Unopposed selection.Unopposed selection. This moves the frequency of This moves the frequency of

one allele in ONE DIRECTIONone allele in ONE DIRECTION.. In the US, these are fewer S.C. In the US, these are fewer S.C.

mutant alleles than in Africamutant alleles than in Africa Where malaria is a problem, having Where malaria is a problem, having

one sickle cell allele does not one sickle cell allele does not increase life expectance.increase life expectance.

3.Different Types of Natural 3.Different Types of Natural SelectionSelection

What can change the What can change the frequency?frequency?

MutationMutation:_________________:_________________

Genetic Drift : ______________Genetic Drift : ______________

Gene _________ (from immigration or Gene _________ (from immigration or emigration)emigration)

3. In Disruptive Selection3. In Disruptive Selection Individuals at both ________ of the Individuals at both ________ of the

phenotypic range are ____________ over phenotypic range are ____________ over intermediate phenotypes. intermediate phenotypes.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 23.12

Individuals that in Individuals that in nature interbreed and nature interbreed and produce _________ produce _________ ___________.___________.

SpeciesSpecies

Physical BarriersPhysical Barriers

Geographic IsolationGeographic Isolation

Whenever a Whenever a ____________barrier ____________barrier divides a divides a population.population.

May cause May cause reproductive reproductive isolationisolation

Reproductive IsolationReproductive Isolation

Occurs when formerly interbreeding Occurs when formerly interbreeding organisms can no longer mate and organisms can no longer mate and produce fertile offspring.produce fertile offspring.

Due toDue to Different habitatsDifferent habitats Different behaviorsDifferent behaviors Different mating timesDifferent mating times

The Debate over the Rate The Debate over the Rate of Evolutionof Evolution: :

Rate of Speciation/Evolution Rate of Speciation/Evolution

11..GRADUALISMGRADUALISM: : Darwin: Evolution occurs at Darwin: Evolution occurs at a slow, steady rate. Differences accumulate a slow, steady rate. Differences accumulate slowly over a long period of time slowly over a long period of time

2. 2. PUNCTUATED EQUILIBRIUMPUNCTUATED EQUILIBRIUM: : Evolution occurs at an irregular rate—long Evolution occurs at an irregular rate—long steady periods of little or no change, steady periods of little or no change, interrupted by short periods of rapid evolutioninterrupted by short periods of rapid evolution

Latter suggested by Niels Eldredge (Museum of Natural History, New York) and Stephen J. Gould (Harvard Latter suggested by Niels Eldredge (Museum of Natural History, New York) and Stephen J. Gould (Harvard University) to explain the frequently observed pattern in the fossil record. University) to explain the frequently observed pattern in the fossil record.

Convergent EvolutionConvergent Evolution

Convergent Convergent evolution: evolution: unrelated unrelated organisms that organisms that have similar traits have similar traits due to adaptation due to adaptation to similar to similar environmental environmental pressurespressures

1.1. Some organisms appear Some organisms appear suddenly in the fossil record. Few suddenly in the fossil record. Few transitional forms found.transitional forms found.

2. 2. Other show gradual changeOther show gradual change..The debate is about the The debate is about the raterate and regularity of evolution—not and regularity of evolution—not about whether evolutionabout whether evolution occurs.occurs.