Evolution: Lamarck Evolution: Lamarck

Evolution: Evolution: Change over Change over timetime

LamarckLamarck Use / disuseUse / disuse Theory of Theory of

inheritance of inheritance of ACQUIRED ACQUIRED traitstraits

Evolution: DarwinEvolution: Darwin Darwin’s Voyage on the HMS BeagleDarwin’s Voyage on the HMS Beagle

Evolution: Darwin / Natural Evolution: Darwin / Natural SelectionSelection

Darwin observed that Darwin observed that organisms produce more offspring than organisms produce more offspring than

the environment can supportthe environment can support organisms VARY in many traitsorganisms VARY in many traits these variations can be inheritedthese variations can be inherited Some traits better fit for the Some traits better fit for the

environment than other traitsenvironment than other traits

Evolution: Darwin / Natural Evolution: Darwin / Natural SelectionSelection

Darwin = individuals best suited for a Darwin = individuals best suited for a particular environment are more likely to particular environment are more likely to survive AND reproduce than those less well survive AND reproduce than those less well adaptedadapted

Darwin saw natural selection as basic Darwin saw natural selection as basic mechanism of evolutionmechanism of evolution As a result, proportion of individuals with As a result, proportion of individuals with

favorable characteristics increasesfavorable characteristics increases POPULATIONS (not individuals) gradually change POPULATIONS (not individuals) gradually change

in allele frequency in response to the environmentin allele frequency in response to the environment

Evolution: Natural SelectionEvolution: Natural Selection

Evolution: Natural Selection vs Evolution: Natural Selection vs Artificial SelectionArtificial Selection

Artificial SelectionArtificial Selection

- man creates pressure- man creates pressure

Four Evidence of EvolutionFour Evidence of Evolution

BiogeographyBiogeography FossilsFossils Comparative AnatomyComparative Anatomy

Homologous StructuresHomologous Structures Comparative EmbryologyComparative Embryology

Molecular BiologyMolecular Biology DNA / Proteins / Amino Acid sequencesDNA / Proteins / Amino Acid sequences

Evidence for Evolution: Evidence for Evolution: FossilsFossils

Transitional Transitional FossilsFossils

Evidence for Evolution: Evidence for Evolution: Comparative AnatomyComparative Anatomy

Homologous StructuresHomologous Structures::Similar structure (what does Similar structure (what does that suggest); different that suggest); different function (what does that function (what does that suggest)suggest)

Evidence For Evolution: Evidence For Evolution: Molecular BiologyMolecular Biology

Convergent vs Divergent Convergent vs Divergent EvolutionEvolution

Analogous structureAnalogous structure: similar function, : similar function, different structuredifferent structure

Ex. Wing of insect and birdEx. Wing of insect and bird Convergent EvolutionConvergent Evolution Divergent EvolutionDivergent Evolution Homologous Homologous

StructuresStructures

Microevolution vs Microevolution vs MacroevolutionMacroevolution

Micro = small changes, still same Micro = small changes, still same speciesspecies

Macro = speciationMacro = speciation MicroevolutionMicroevolution = change in = change in allele allele

frequenciesfrequencies in a gene pool in a gene pool

Microevolution: Gene PoolMicroevolution: Gene Pool

Gene poolGene pool = = total numbers total numbers of allele in a of allele in a populationpopulation

Allele Allele frequencyfrequency = % = % of that specific of that specific allele in gene allele in gene poolpool

Hardy Weinberg EquilibriumHardy Weinberg Equilibrium

Hardy-Weinberg equilibrium: Hardy-Weinberg equilibrium: even if alleles are shuffled in the even if alleles are shuffled in the next generation (new genotypes next generation (new genotypes appear) allele frequency / appear) allele frequency / proportions in the gene pool proportions in the gene pool stay the same from generation stay the same from generation to generationto generation

Hardy-Weinberg EquilibriumHardy-Weinberg Equilibrium

Large populationLarge population Isolated populationIsolated population No genetic mutationsNo genetic mutations Random MatingRandom Mating No Natural SelectionNo Natural Selection

Hardy-Weinberg EquilibriumHardy-Weinberg Equilibrium

ALLELE ALLELE FREQUENCYFREQUENCY

p = “A” freqp = “A” freq q = “a” freqq = “a” freq

p + q = 1p + q = 1

GENOTYPE FREQUENCYGENOTYPE FREQUENCY pp22 = “AA” freq = “AA” freq 2pq = “Aa” freq2pq = “Aa” freq qq22 = “aa” freq = “aa” freq

pp22 + 2pq + q + 2pq + q22 = 1 = 1

Hardy-Weinberg: Hardy-Weinberg: Genotype & Allele Genotype & Allele

FrequenciesFrequencies

Hardy-Weinberg: Hardy-Weinberg: Genotype & Allele Genotype & Allele

FrequenciesFrequencies

Hardy-Weinberg Hardy-Weinberg Practice ProblemPractice Problem

In a certain population, the frequency In a certain population, the frequency of homozygous curly haired (HH) is of homozygous curly haired (HH) is 64%. What percentage of the 64%. What percentage of the population has curly hair?population has curly hair?

Given: pGiven: p22 = .64 Find: p = .64 Find: p22 + 2pq + 2pq p = .8 q = .2 2(.8)(.2) = .32 or 32%p = .8 q = .2 2(.8)(.2) = .32 or 32% 64% (HH) + 32% (Hh) = 96% curly 64% (HH) + 32% (Hh) = 96% curly

hairedhaired

5 Causes of Microevolution5 Causes of Microevolution

Population becomes SMALL due to Population becomes SMALL due to chance: chance: GENETIC DRIFTGENETIC DRIFT

Population is NOT isolated: Population is NOT isolated: GENE GENE FLOWFLOW

Mutations occurMutations occur Mating is NOT randomMating is NOT random Natural selection exists: some traits Natural selection exists: some traits

are better fit than othersare better fit than others

Causes of Microevolution:Causes of Microevolution:GeneticGenetic Drift: Gene pool Drift: Gene pool changing due to CHANCEchanging due to CHANCE

BOTTLENECK BOTTLENECK EFFECTEFFECT Pop shrinks due to Pop shrinks due to

natural disasternatural disaster

FOUNDER EFFECTFOUNDER EFFECT Colony leavesColony leaves

Gene Flow & Gene Flow & Non Random MatingNon Random Mating

Gene FlowGene Flow

NONrandom NONrandom MatingMating

Causes of Microevolution:Causes of Microevolution:Natural SelectionNatural Selection

3 outcomes of Natural Selection:3 outcomes of Natural Selection: Stabilizing, Directional, Disruptive/DiversifyingStabilizing, Directional, Disruptive/Diversifying

Macroevolution: SpeciationMacroevolution: Speciation

SpeciationSpeciation – the creation of new – the creation of new speciesspecies

Species:Species: a population or group of populations a population or group of populations

whose members can interbreed and whose members can interbreed and produce fertile offspringproduce fertile offspring

Reproductive BarriersReproductive Barriers

Reproductive barriers prevents Reproductive barriers prevents different species from mating with different species from mating with each other:each other: Mating times / seasons differentMating times / seasons different Different habitatDifferent habitat Different mating behavior so little Different mating behavior so little

attraction between speciesattraction between species

Reproductive Barrier:Reproductive Barrier:Geographic BarrierGeographic Barrier

Allopatric SpeciationAllopatric Speciation: When a : When a population is cut off from its parent population is cut off from its parent population, species evolution may population, species evolution may occuroccur gene pool is changed by natural gene pool is changed by natural

selection, genetic drift, or mutationselection, genetic drift, or mutation

Geographic Barrier:Geographic Barrier:Adaptive RadiationAdaptive Radiation

Adaptive radiationAdaptive radiation (ex of allopatric speciation) (ex of allopatric speciation) on an island chain – from one main species on an island chain – from one main species there are multiple different species evolvingthere are multiple different species evolving