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Questions to Ponder Questions to Ponder TRUE/FALSETRUE/FALSE

1.1. You can web your hands if you try. You can web your hands if you try. 2.2. You can acquire traits in your lifetime that will You can acquire traits in your lifetime that will

help you survive.help you survive.3.3. All organisms have the same chance for All organisms have the same chance for

survival. survival. 4.4. All organisms need the same favorable trait. All organisms need the same favorable trait. 5.5. Evolution of most organisms occurs during Evolution of most organisms occurs during

their lifetime. their lifetime.

THEORIES OF EVOLUTION: THEORIES OF EVOLUTION: LAMARCK VS. DARWIN LAMARCK VS. DARWIN

Lamarck (1744-1829)Lamarck (1744-1829) Darwin (1809-1882)Darwin (1809-1882)

LAMARCK’S THEORIESLAMARCK’S THEORIES Jean Baptiste de Lamarck (1744-1829)Jean Baptiste de Lamarck (1744-1829)

TheoryTheory: Similar species descend from a : Similar species descend from a common ancestor (evident in fossil record)common ancestor (evident in fossil record)

To Explain how species change he hypothesized:To Explain how species change he hypothesized: Acquired traitAcquired trait: a trait NOT determined by : a trait NOT determined by

genes, it arises during an organisms lifetime as genes, it arises during an organisms lifetime as a result of behavior and can be passed onto a result of behavior and can be passed onto offspring offspring

Acquired TraitAcquired Trait Example: giraffes Example: giraffes

evolved their long evolved their long necks by each necks by each generation generation stretching further stretching further to get leaves in to get leaves in trees and that this trees and that this change in body change in body shape was then shape was then inherited.  inherited. 

CHARLES DARWIN (1809-1882)CHARLES DARWIN (1809-1882)

Darwin was recommended to be a Darwin was recommended to be a naturalist on the ship H.M.S. Beagle naturalist on the ship H.M.S. Beagle

Sailed around the World in Beagle for five Sailed around the World in Beagle for five years-collected specimens and recorded years-collected specimens and recorded lots of data lots of data

Voyage of the BeagleVoyage of the Beagle

Darwin reasoned that Earth is dynamic, Darwin reasoned that Earth is dynamic, constantly changing –earthquakes, constantly changing –earthquakes, volcanoes, mountain formation- volcanoes, mountain formation-

Changes are a long slow process-Changes are a long slow process-organisms must adapt to changes or ? organisms must adapt to changes or ?

The study of the Galapagos finches led Darwin to his TWO theories!

Darwin’s TheoriesDarwin’s Theories

Descent with ModificationDescent with Modification Newer forms appearing in the fossil record are Newer forms appearing in the fossil record are

modified descendents of older species modified descendents of older species

All species had All species had descended from one or a few descended from one or a few original types of life original types of life

Descent With Modifications - tree of life that links all living things!

Modification by Natural SelectionModification by Natural Selection

Describes how evolution occurs!Describes how evolution occurs!

1.1. Living things face a constant Living things face a constant strugglestruggle for for existenceexistence

**organisms in nature produce more than **organisms in nature produce more than can survive**can survive**

2. Variation exists within populations: 2. Variation exists within populations: - mutation - mutation

- Crossing Over/Independent - Crossing Over/Independent

Assortment (make different gametes)Assortment (make different gametes)

- Sexual reproduction - Random - Sexual reproduction - Random fusionfusion

of two gametesof two gametes Through mutation three variations of neck length exist: Short, Medium and long necks.

**POPULATIONS

HAVE

VARIATIONS**

3. 3. Non-random Non-random SurvivalSurvival and Reproduction and Reproduction

-Individuals with traits best -Individuals with traits best suitedsuited to their to their environment (environment (favorable traitsfavorable traits) survive and ) survive and reproduce in high numbers reproduce in high numbers

** SOME VARIATIONS ARE FAVORABLE**** SOME VARIATIONS ARE FAVORABLE**

-Having a high number of favorable traits gives -Having a high number of favorable traits gives the organisms an the organisms an adaptive advantageadaptive advantage

The long neck giraffe has the “best advantage” and therefore reproduces more than the others

4. These favorable traits have to be heritable (able 4. These favorable traits have to be heritable (able to be passed down to offspring)to be passed down to offspring)

**SURVIVORS HAVE FAVORABLE TRAITS TO **SURVIVORS HAVE FAVORABLE TRAITS TO PASS TO OFFSPRING**PASS TO OFFSPRING**

- Fitness:- Fitness: organisms ability to survive and organisms ability to survive and pass pass on its geneson its genes

Long neck giraffes have baby long neck giraffes

5. 5. Adaption:Adaption: The number of organisms with The number of organisms with favorable traits increases favorable traits increases

Populations Populations geneticallygenetically change to become change to become more suited to the environmentmore suited to the environment

The entire population of giraffes now ALL have long necks

**POPULATIONS

CHANGE OVER

TIME**

Summary: Summary:

Natural selection is not an active process: Natural selection is not an active process: the environment “selects” the traits that the environment “selects” the traits that are favorable and those that are not are favorable and those that are not

If the environment changes, so must the ...If the environment changes, so must the ...

Outcomes of Natural SelectionOutcomes of Natural Selection

Most traits resemble bell curve for Most traits resemble bell curve for phenotypesphenotypes

Natural Selection can alter variation in a population in three ways:

Stabilizing Selection Stabilizing Selection

Favors individuals with the Favors individuals with the averageaverage phenotype of the trait (average form have phenotype of the trait (average form have the highest fitness)the highest fitness)

Directional SelectionDirectional Selection

Environmental conditions favor individuals Environmental conditions favor individuals of one of one extremeextreme phenotype phenotype

Disruptive Selection Disruptive Selection

Environmental conditions favor individuals Environmental conditions favor individuals of both of both extremesextremes of the phenotype. of the phenotype.

Can lead to creation of a new speciesCan lead to creation of a new species

SameStructureDifferentFunction

HomologousStructure

SameFunctionDifferentStructure

AnalogousStructure

ReducedFunction

ofbody part

VestigialStructure

similiarembryos

Similaramino acids

andproteins

similarDNA

Law ofSuperpositionNew layers on

top of old layers

incompleterecordof life

on Earth

Evidence of Evolution

SameStructureDifferentFunction

HomologousStructure

SameFunctionDifferentStructure

AnalogousStructure

ReducedFunction

ofbody part

VestigialStructure

ComparativeAnatomy

similiarembryos

Embryology

Similaramino acids

andproteins

similarDNA

MolecularBiology

Law ofSuperpositionNew layers on

top of old layers

incompleterecordof life

on Earth

FossilRecord

Evidence of Evolution

Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy

Homologous Structures: same structure but Homologous Structures: same structure but different functiondifferent function

Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy

Analogous StructureAnalogous Structure

- same function but same function but

different structuresdifferent structures

Evidence of EvolutionEvidence of EvolutionComparative AnatomyComparative Anatomy

Vestigial Structure - body part that is Vestigial Structure - body part that is reduced or has no usereduced or has no use

Evidence of EvolutionEvidence of EvolutionEmbryology Embryology

Evidence of EvolutionEvidence of EvolutionFossil RecordFossil Record

Evidence of Evolution Evidence of Evolution Molecular BiologyMolecular Biology

Patterns of Evolution Patterns of Evolution

Ways species change to adapt to their habitats:

o Coevolution

o Convergent Evolution

o Divergent Evolution

Patterns of Evolution Patterns of Evolution

Coevolution:Coevolution: Two or more species change Two or more species change together!together!

Examples:Examples:

1)1) Predator/PreyPredator/Prey

2)2) Plant and pollinatorPlant and pollinator

Patterns of Evolution Patterns of Evolution Convergent: Convergent: Two dissimilar species Two dissimilar species

becoming similarbecoming similar

Environment selects for similar Environment selects for similar phenotype (but ancestors were phenotype (but ancestors were different)different)

Patterns of Evolution Patterns of Evolution Divergent: Two similar species become Divergent: Two similar species become

dissimilar in response to environmentdissimilar in response to environment