Chapter 15.2 evidence of evolution

15.2 Evidence of Evolution15.2 Evidence of EvolutionMain idea: Main idea: Multiple lines of evidence support the Multiple lines of evidence support the theory of evolution.theory of evolution.Objectives: Objectives: Describe how fossils provide evidence of Describe how fossils provide evidence of

evolution.evolution. Discuss morphological evidence of evolution.Discuss morphological evidence of evolution. Explain how physiology and biochemistry Explain how physiology and biochemistry

provide evidence of evolution.provide evidence of evolution.New VocabularyNew Vocabulary Derived traitDerived trait Ancestral traitAncestral trait Homologous structureHomologous structure Vestigial structureVestigial structure Analogous structureAnalogous structure

EmbryoEmbryo FitnessFitness MimicryMimicry CamouflageCamouflage

Support for EvolutionSupport for EvolutionThe theory of The theory of evolutionevolution states that all states that all organisms on Earth have descended from a organisms on Earth have descended from a common ancestorcommon ancestor..The The fossil recordfossil record offers some of the most offers some of the most significant evidence of evolutionary change.significant evidence of evolutionary change. Fossils provide a Fossils provide a recordrecord of species that of species that

lived long ago.lived long ago. Fossils show that ancient species share Fossils show that ancient species share

similarities similarities with species that now live on with species that now live on Earth.Earth.

The giant armadillo-like The giant armadillo-like glyptodont, glyptodont, Glyptodon,Glyptodon,is is an an extinctextinct animal that animal that Darwin thought must be Darwin thought must be related to the related to the livingliving armadillos of today.armadillos of today.The The fossil recordfossil record provides provides information for information for determining the ancestry determining the ancestry of organisms and the of organisms and the patternspatterns of evolution. of evolution.

Support for EvolutionSupport for EvolutionThe Fossil RecordThe Fossil Record

Two major classes of traits:Two major classes of traits:Derived traits are Derived traits are newly evolved newly evolved

features, such as feathers, that do not features, such as feathers, that do not appear in the fossils of common appear in the fossils of common ancestors.ancestors.

Ancestral traits Ancestral traits are more are more primitive primitive featuresfeatures, such as teeth and tails, that , such as teeth and tails, that do appear in ancestral forms.do appear in ancestral forms.


Transitional fossils provide detailed Transitional fossils provide detailed patternspatterns of evolutionary change for of evolutionary change for ancestors of many modern animals, ancestors of many modern animals, including mollusks, horses, whales and including mollusks, horses, whales and humans.humans.Example:Example: ArcheopteryxArcheopteryx

Shares features of Shares features of bothboth dinosaurs dinosaurs and birds.and birds.


Homologous Homologous structures are structures are anatomically anatomically similarsimilar structures structures inheritedinherited from a from a common common ancestor.ancestor.The forelimbs of The forelimbs of vertebrates are vertebrates are adapted for adapted for different uses, different uses, but they all have but they all have similar bones.similar bones.

Similar Similar structure; structure; differentdifferent functionfunction..

Support for EvolutionSupport for EvolutionComparative AnatomyComparative Anatomy

Vestigial structures are Vestigial structures are the the reducedreduced forms of forms of functional structures in functional structures in other organisms.other organisms.Evolutionary theory Evolutionary theory predicts that features predicts that features of ancestors that no of ancestors that no longer have a function longer have a function for that species will for that species will become become smallersmaller over over time until they are time until they are lostlost..

Examples: Snake pelvis, Examples: Snake pelvis, human human appendix,appendix, blind blind fish and salamanders that fish and salamanders that live in caves but have live in caves but have eyes.eyes.


Analogous structures can be Analogous structures can be used for the used for the same purpose same purpose and can be and can be similarsimilar in in construction, but are construction, but are notnot inheritedinherited from a common from a common ancestor.ancestor.Show that functionally similar Show that functionally similar features can evolve features can evolve independentlyindependently in similar in similar environments.environments.DifferentDifferent structure; structure; samesame function; function;


Analogous structures example:Analogous structures example: Human eye and squid eyeHuman eye and squid eye

SimilaritiesSimilarities The iris to regulate light entering the lensThe iris to regulate light entering the lens Each eye is filled with fluidEach eye is filled with fluid Both eyes use a lens to focusBoth eyes use a lens to focus

function; function;


An An embryoembryo is an early pre-birth stage of an is an early pre-birth stage of an organismorganism’’s development.s development.Vertebrate Vertebrate embryos exhibit embryos exhibit homologous homologous structuresstructures during certain during certain phases of phases of development development but become but become totally different totally different structures in structures in the adult forms.the adult forms.

Support for EvolutionSupport for EvolutionComparative EmbryologyComparative Embryology

Comparative BiochemistryComparative Biochemistry

Common ancestry Common ancestry can be seen in the can be seen in the complex complex metabolic metabolic moleculesmolecules that that many different many different organisms organisms shareshare..

Support for EvolutionSupport for Evolution

The genomes of humans and chimpanzees The genomes of humans and chimpanzees differ by only about 1% of their genetic makeupdiffer by only about 1% of their genetic makeup

Geographic DistributionGeographic DistributionThe The distributiondistribution of plants and animals that of plants and animals that Darwin saw during his travels first suggested Darwin saw during his travels first suggested evolution to Darwin.evolution to Darwin.

Rabbit in EuropeRabbit in Europe Mara in S. AmericaMara in S. America

Support for EvolutionSupport for Evolution

Scientists have Scientists have confirmed and confirmed and expanded Darwinexpanded Darwin’’s s study of the distribution study of the distribution of plants and animals of plants and animals around the world in a around the world in a field of study now called field of study now called biogeography.biogeography.

Evolution is intimately linked with Evolution is intimately linked with climateclimate and and geological geological forcesforces..

Geographic DistributionGeographic DistributionSupport for EvolutionSupport for Evolution

AdaptationAdaptation

An An adaptationadaptation is a trait is a trait shaped by natural shaped by natural selection that selection that increasesincreases an organisman organism’’s s reproductive success.reproductive success.

FitnessFitness is a measure of the relative is a measure of the relative contribution an individual trait makes to the contribution an individual trait makes to the next generation. It is often measured as the next generation. It is often measured as the number of number of reproductivelyreproductively viable offspring that viable offspring that an organism produces in the next generation.an organism produces in the next generation.

Camouflage allows Camouflage allows organisms to become organisms to become almost almost invisibleinvisible to to predators. Some species predators. Some species have evolved morphological have evolved morphological adaptations that allow them adaptations that allow them to blend in with their to blend in with their environments.environments.

MimicryMimicry is another is another morphological adaptation morphological adaptation that allows one species to that allows one species to evolve to evolve to resembleresemble another speciesanother species..

AdaptationAdaptationTypes of AdaptationTypes of Adaptation

Can you see the peppered moth?Can you see the peppered moth?


When disturbed, When disturbed, this octopus flashes this octopus flashes and intensifies its and intensifies its stripes, resembling stripes, resembling a poisonous sea a poisonous sea snake. Unlike the snake. Unlike the sea snake, the sea snake, the octopus venom is octopus venom is harmlessharmless


Antimicrobial Antimicrobial resistanceresistance - An - An antibiotic is a antibiotic is a medicine that slows medicine that slows or kills the growth of or kills the growth of bacteria.bacteria. Some bacteria Some bacteria

have evolved a have evolved a resistanceresistance to to certain antibiotics.certain antibiotics.

People infected with resistant bacteria can People infected with resistant bacteria can never never get rid of get rid of it.it.


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Chapter 15.2 evidence of evolution