Ch 22 Descent with Ch 22 Descent with ModificationModification

• FossilsFossils- Relics or impressions of organisms - Relics or impressions of organisms from the past, usually found in sedimentary from the past, usually found in sedimentary rock.rock.

• PaleontologyPaleontology- the study of fossils- the study of fossils• CuvierCuvier- Catastrophism- each boundary in - Catastrophism- each boundary in

strata corresponded to a catastrophe that strata corresponded to a catastrophe that destroyed the species living there at that time.destroyed the species living there at that time.

• HuttonHutton- gradualism-profound change is the - gradualism-profound change is the cumulative product of slow but continuous cumulative product of slow but continuous processes.processes.

• LyellLyell- Uniformitarianism- earth processes - Uniformitarianism- earth processes have not changed throughout history.have not changed throughout history.

Fossils Fossils fish oldest footprints

Descent with modification Descent with modification

• Darwin was influenced by both Hutton and Darwin was influenced by both Hutton and Lyell.Lyell.

• Earth must be very old, not 6000 years as Earth must be very old, not 6000 years as theologians suggest.theologians suggest.

• Lamarck- Use and disuse- but was in Lamarck- Use and disuse- but was in inheritedinherited..

DarwinDarwin

• Charles Darwin- Charles Darwin- 1809-18821809-1882

• HMS Beagle 1831HMS Beagle 1831

DarwinDarwin

• Did not use the word evolution, but instead “Descent with Did not use the word evolution, but instead “Descent with modification”modification”

• Natural selection:Natural selection:• All species produces more offspring than can possibly exist.All species produces more offspring than can possibly exist.• Only a fraction will survive to reproduce. Only a fraction will survive to reproduce. • Resources and environment dictate the survival rate.Resources and environment dictate the survival rate.• All individuals of a population vary extensively.All individuals of a population vary extensively.• Individuals best suited to environment will survive and Individuals best suited to environment will survive and

reproduce.reproduce.• Natural selection is the result of change over enormous Natural selection is the result of change over enormous

tracts of time.tracts of time.• Stanford evolution rap

Evidence of EvolutionEvidence of Evolution

• Biogeography- geographical distribution of a Biogeography- geographical distribution of a species.species.

• Fossil record-Transitional fossils linking past and Fossil record-Transitional fossils linking past and presentpresent

• Comparative Anatomy- Homologous structuresComparative Anatomy- Homologous structures• Vestigial organs-No longer has a function.Vestigial organs-No longer has a function.• Comparative EmbryologyComparative Embryology• Ontogeny- development of an individual organismOntogeny- development of an individual organism• Phylogeny- evolution of the speciesPhylogeny- evolution of the species• Molecular Biology- common genetic codeMolecular Biology- common genetic code• claymation evolution

PhylogenyPhylogeny• Comparative Anatomy Comparative Anatomy

and Embryologyand Embryology

Ch 23- The Evolution of Ch 23- The Evolution of PopulationsPopulations• Population-group of individuals of the same species.Population-group of individuals of the same species.• Gene Pool- total aggregate of genes in a populationGene Pool- total aggregate of genes in a population• Hardy-Weinberg theorem-shuffling of alleles by Hardy-Weinberg theorem-shuffling of alleles by

meiosis and random fertilization has no effect on meiosis and random fertilization has no effect on overall genetic structure of a population. Gene pool overall genetic structure of a population. Gene pool in equilibrium(non-evolving)in equilibrium(non-evolving)

• Must have:Must have:• Very large populationsVery large populations• Isolation from other populationsIsolation from other populations• No net mutationsNo net mutations• Random matingRandom mating• No natural selectionNo natural selection• Hardy-Weinberg equation Hardy-Weinberg equation examples

Hardy Weinburg sitesHardy Weinburg sites

• hardy weinburg tutorialhardy weinburg tutorial

• http://www.biologyjunction.com/http://www.biologyjunction.com/hardyweinberg_problems.htmhardyweinberg_problems.htm

• flash animationsflash animations

• TutorialTutorial

Ch 23- cont.Ch 23- cont.• Microevolution –generation to generation Microevolution –generation to generation

change in frequency of alleles.change in frequency of alleles.• Causes:Causes:• Genetic Drift-changes in gene pool due to Genetic Drift-changes in gene pool due to

chancechance• Gene Flow-genetic exchange between Gene Flow-genetic exchange between

populationspopulations• Mutations-change in organism’ DNAMutations-change in organism’ DNA• Natural Selection- accumulates and Natural Selection- accumulates and

maintains favorable genotypes in a maintains favorable genotypes in a population.population.

Natural SelectionNatural Selection

• Stabilizing - Directional - Stabilizing - Directional - DiversifyingDiversifying

Ch 24- Origin of SpeciesCh 24- Origin of Species• Species- interbreed with each other Species- interbreed with each other

and have fertile offspring. Cannot and have fertile offspring. Cannot produce fertile offspring with other produce fertile offspring with other species.species.

• Prezygotic barriers- impede Prezygotic barriers- impede fertilization of egg if different species fertilization of egg if different species attempt to breed.attempt to breed.

• Postzygotic barriers- prevent the Postzygotic barriers- prevent the hybrid zygote from developing into a hybrid zygote from developing into a viable fertile adult.viable fertile adult.

• ligers and tigonsligers and tigons

SpeciationSpeciation

• Allopatric speciation-Allopatric speciation- a geographical a geographical barrier physically isolates populations and barrier physically isolates populations and blocks gene flow.blocks gene flow.

• Sympatric speciation-Sympatric speciation- intrinsic factors, intrinsic factors, such as chromosomal change (in plants) such as chromosomal change (in plants) and nonrandom mating (in animals) alter and nonrandom mating (in animals) alter gene flow. Populations become genetically gene flow. Populations become genetically isolated even though their ranges overlap.isolated even though their ranges overlap.

• Adaptive radiation- evolution of diversely Adaptive radiation- evolution of diversely adapted species from a common ancestor.adapted species from a common ancestor.

Origin of Species Origin of Species

Adaptive Adaptive radiation-radiation- evolution of evolution of

diversely diversely adapted adapted

species from species from a common a common ancestor.ancestor.

Ex Adaptive Ex Adaptive radiation on radiation on

Island Island Chains.Chains.

SpeciationSpeciation• GradualismGradualism- -

gradually gradually diverge more diverge more and more in and more in morphology due morphology due to adaptations.to adaptations.

• Punctuated Punctuated equilibrium-equilibrium- new species new species change most as change most as it buds from it buds from parents and parents and then changes then changes little.little.

Ch 25- Tracing Ch 25- Tracing PhylogenyPhylogeny

• Fossil Fossil record- record- Order of Order of fossils in fossils in sedimentary sedimentary rocks. rocks. Relative Relative datingdating. .

• Absolute Absolute DatingDating or or Radiometric Radiometric dating of dating of fossilsfossils

Tracing PhylogenyTracing Phylogeny

• Phylogeny has a biogeographical Phylogeny has a biogeographical basis in continental drift. The basis in continental drift. The supercontinent Pangaea and its supercontinent Pangaea and its breakup explain many breakup explain many biogeographical puzzles.biogeographical puzzles.

• Mass extinction- followed by grand Mass extinction- followed by grand episodes of adaptive radiation.episodes of adaptive radiation.