5Isn’t evolution just a theory? A theory is a ____________, _______, explanation of phenomena that have occurred in the natural world, like the theory of __________________, ________, and _____________.well-supportedtestablegravitational attractioncell theoryatomic theory
6_________________ is found naturally in all populations GENETIC VARIATION
7copyright cmassengale See Natural SelectionDriving force for evolutionIdea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable (genetic variation)During the struggle for resources, strongest survive & reproduce (natural selection).copyright cmassengale
8Darwins idea from Malthus …….. ______________________ means that members of each speciesmust ________ for food, space, andother __________.STRUGGLE FOR EXISTANCECOMPETERESOURCES
9WHAT IS DARWIN’S THEORY? Some organisms in a ________are ________ to survive. Natural Selectionpopulationless likely
10Darwin developed two main theories of natural selection: 1 Darwin developed two main theories of natural selection: 1. DESCENT WITH MODIFICATION 2. MODIFICATION BY NATURAL SELECTIONRd pgs in text book
11____________________________ WHAT IS DARWIN’S THEORY?DESCENT WITH MODIFICATION____________________________suggests that each species has___________, with ________,from other species over time.This idea suggests that all livingspecies are ____________________,and that all species, living and extinct,share a _________________.DESCENDEDCHANGESRELATED TO EACH OTHERCOMMON ANCESTOR
12Common Descent with Modification Idea that organisms change with time, diverging from a common formThis is what Caused evolution of new species
13Descent With Modification Takes Place Over Long Periods of TimeNatural Selection Can Be Observed As Changes InEcological Niches (their role in society)Body StructuresHabitats (where they live)copyright cmassengale
14Descent With Modification Species Today Look Different From Their AncestorsEach Living Species HasDescendedWith ChangesFrom Other SpeciesOver Timecopyright cmassengale
16Descent With Modification ImpliesAll Living Organisms Are RelatedSingle Tree of LifeDNA, Body Structures, Energy SourcesCommon DescentAll Species, Living & Extinct, Were Derived From Common Ancestorscopyright cmassengale
17Natural Variation and Artificial Selection Abandoned The Idea That Species Were Perfect & UnchangingObserved Significant Variation in All Species ObservedObserved Farmers Use Variation To Improve Crops & LivestockCalled Selective Breedingcopyright cmassengale
18mutation sexual reproduction ARTIFICIAL SELECTION WORKS In artificial selection, ____________ provides the _________ through _________ and _________________ and ______________ those traits that they find ______.NATUREvariationmutation sexual reproductionhumans selectusefulEX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.
20Butterball turkeys have to do with EVOLUTION? What do oranges andButterball turkeys have to dowith EVOLUTION?THINK ABOUT IT
21This is what a butterball turkey and a naval orange have in common This is what a butterball turkey and a naval orange have in common. They have been artificially selected and sometimes genetically modified.
22Major Problem in Darwin’s Theory No mechanism (the how) to explain natural selectionHow could favorable variations be transmitted to later generations?With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was found.copyright cmassengale
23Evidence of Evolution Key Concept Darwin Argued That Living Things Have Been Evolving On Earth For Millions of Years. Evidence For This Process Could Be Found In:1.The Fossil Record2.The Geographical Distribution of Living Species3.Homologous Structures of Living Organisms4.Similarities In Early Development
24How Do We Know Evolution Happens? The Fossil Record –______ are the ________________________found in layers of rockin the Earth.Fossilsremainsof ancient organisms
25How Do We Know Evolution Happens? The layers of rock tell the history of the_____, while the _____ found withinthe rock tell a history of ___.The fossils are thoughtto be the ________ asthe rock theyare found in.Earthfossilslifesame age
26Movement of Earth’s Crust Section 15-2Earthquakes and volcanoescause uplifting of the layers of theEarth, taking the fossils alongSea levelFossils ofmarinefish foundon themountain-sides ofsouthwestWyoming,which atone timewascoveredby aninland seaFish die inthe oceanand arecovered insediment.Over timeand underincreasingpressure,the remainsbecomesfossilizedSedimentary rocks form in horizontal layers.When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers.As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed.
27TRANSITIONAL FOSSILS HAVE BEEN FOUND Scientific American; Dec 2005; Vol 293; p
28Geographic distribution of Fossils of similar species Fossils of similar species have been found in different areas. Body structure is similar enough to suggest they were related and could have once been the same species.
29Figure 15–14 Geographic Distribution of Living Species Section 15-3Differencesbetween_____________muskratand coypushow _________evolution, whilesimilarities______________capybaraand coypu show___________evolution.BeaverNORTH AMERICAMuskratCapybaraSOUTH AMERICACoypuBeaver and MuskratCoypu and Capybaraclosely-relatedBeaver and capybaraare _____________________ living in very ________ environments,while beaver and musk-rat are ______________________ living in a______ environment.Differences betweenbeaver and capybarashow _________evolution, whilesimilaritiesbetween beaver andmuskrat show __________ evolution.closely-relatedspeciesdivergentdifferentdistantly-relateddistantly-relatedspeciessimilarconvergentdivergentconvergent
30closely related different species If Darwin’s theory is correct you would expect to find ____________ yet _______________ living in aGeographic region as they spread into nearby habitats and evolve. (development of traits suited to their particular environment)closely relateddifferent speciesThat’s EXACTLY what we do see!
31When a single species or small group of species has evolved through ___________________ into diverse forms that live in different ways = ____________________________________natural selectionadaptive radiation OR divergent evolutionEx:Galápagos finchesIt is called Divergent evolution because they all started with a common ancestor and diverged or radiated out into different species from there.
33The _____ of Galapagos finches have ______ to eating a _____ of _____. GALAPAGOS FINCHESThe _____ of Galapagos finches have______ to eating a _____ of _____.beaksadaptedvarietyfoods
34different species far apart more alike If Darwin’s theory is correct you would also expect to find _______________ living in ________ geographic regionsbut similar habitats becoming ________ as they adapt to ______________.different speciesfar apartmore alikesimilar ecosystemsThat’s EXACTLY what we do see!
35Sometimes different organisms evolve in different places or at different times but in ____________________ environments…and end up looking very similar.Process by which unrelated organisms come to resemble each other = _______________________ converge means come together or become more alike.ecologically similarconvergent evolution
36This is the opposite of divergent evolution This is the opposite of divergent evolution. In divergent evolution, species were diverging and becoming more different from each other,BUT HERE, they are adapting to similar environments even though they are not living together and become more alike. They LOOK similar because their environments are similar even if they aren’t in the same place!
37Whales and sharks have a _____ body design Whales and sharks have a _____ body designeven though they are very _______ organisms(one is a fish; the other, a mammal)because they have _________________ to living in a _____ environment.similardifferentindependently adaptedsimilar= CONVERGENT EVOLUTION
38Whales are closely related to wolves, but don’t look or act much like them = divergent evolutionConclusion:The pressure ofthe environmentdrives evolutionWhales are distantly relatedto sharks, but look and act morelike them =convergent evolution
39How fast does evolution operate? Darwin believed evolutionhappened slowly over along timeIf biological change is at a slow pace, it is called ____________.gradualism
40bursts Fossil record shows evolution happens more in _____. Pattern of a long stable period interrupted by a brief period of more rapid change=____________burstsPunctuatedEquilibrium
41Punctuated equilibrium is any sudden, rapid change in a species and can be genetic (mutation) or the result of other causes, such as huge and sudden changes in the environment that result in more rapid changes in the organism
42Gradualism and Punctuated Equilibrium Gradualism and punctuated equilibrium are two ways in which the evolution of a species can occur. A species can evolve by only one of these, or by both.Scientists think that species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.
43Evolutionary Time Scales Macroevolution: Long time scale events that create and destroy species.copyright cmassengale
44Evolutionary Time Scales Microevolution:Short time scale events (generation-to-generation) that change the genotypes and phenotypes of populationscopyright cmassengale
45Homologous Body Structures – Structures, like the limbs of vertebrates, look very _______,but are made from the__________, becausethey are made fromthe same clump of_____________ cellsin the _______.differentsame bonesundifferentiatedembryoImage from:
47Homologous Body Structures Scientists Noticed Animals With Backbones (Vertebrates) Had Similar Bone StructureMay Differ In Form or FunctionLimb Bones Develop In Similar PatternsArms, Wings, Legs, Flippers
48Homologous Body Structures If you look at these organisms DNA you will see structures That Have Different Mature Forms…. But Develop From The Same Embryonic TissuesStrong Evidence That All Four-Limbed Animals With Backbones Descended, With Modification, From A Common AncestorHelp Scientist Group Animals
49 Homologous Body Structures Section 15-3TurtleAlligatorBirdMammalAncient lobe-finned fish
50homologous body structures Some _______________________are _______ and have no usefulfunction even though they are still present, like ________in whales and boa constrictors, or a ____ and ________________in humans.homologous body structuresvestigialhipbonestailcecum (appendix)
51Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a _____.cecumIn humans the cecumis shrunken and unused.It is our _________appendix
52Why grow a tail and then lose it? HUMAN EMBRYO_________________has a tail at 4 weeksTail disappears atabout 8 weekstail
53WHY DOES EVOLUTION MATTER NOW? Can see Natural selection happen7.____________________________EX: Peppered MothsThere is a natural variation in populations of peppered moths.___________________________________TypicaCarbonariaTypica form - lighterCarbonaria form - darker
54Why would an organism possess organs ___ ________________? with Skinks are a type of lizard. In some species, legs have become so small they _____________ in walking.no longerfunctionWhy would an organism possess organs ___ ________________?withlittle or no functionOne explanation:The ________ is present to make the organ, but_________________ through ______________.If the organ is not vital to survival, thennatural selection would cause its elimination.gene codefunction has been lostchange over time
55Homologous Body Structures Not All Serve Important FunctionsVestigial OrgansAppendix In ManLegs On Skinks
56Humans have many other nonfunctional vestigial genes called ________________. EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are ___________.PSEUDOGENESnonfunctional
57Similarities In Early Development Embryonic Structures Of Different Species Show Significant SimilaritiesEmbryo – early stages of vertebrate development
58Similarities in Embryology 5. _____________________________ of many animals with back-bones are very similar.Similarities in EmbryologyEmbryosImage from:
59It is clear that the same groups of _____________ cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all _______ from a _______________.undifferentiatedevolvedcommon ancestorImage from:
60In recent years, the burning of cleaner fuels and Clean Air The ___________ form was the predominant form in England _____________________________.Around the middle of the 19th century the ______ form began to appear. It was first reported in By % of the moths in Manchester were the ____ variety.In recent years, the burning ofcleaner fuels and Clean Airregulations has reduced thepollution there and the______ colored mothshave increased in numbers.light coloredprior to the Industrial Revolutiondarkerdarklighter
61____________________________ EX: Changes in disease-causing microbes that produce new organisms and __________.____________________________________You Can see Natural selection happennew diseasesBird fluHIVAntibiotic-resistant tuberculosis
62Evolution of pesticide resistance in response to selection
63Evidence for Evolution – Evolution Observed Evolution of drug-resistance in HIV
64Types of SelectionDisruptive-P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Disruptive Selection.wmvStabilizing-P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Stabilizing Selection.wmvDirectional-P:\PLC Biology\Unit 8 - Evolution\Video, Web, and PPT Supplements\Directional Selection.wmv
65____________ and ________ TODAY we can understand how evolution works better than Darwin ever could because of our knowledge about____________ and ________genesDNA
66Because members of a population interbreed, they share a common group of genes called a ___________ A gene pool consists of ____________ present in a population, including all the different _________.GENE POOLALL the genesalleles
71change the __________________ of alleles in population! SEXUAL REPRODUCTION_______________________IS THE MAJOR SOURCE OF VARIATION IN POPULATIONS, but it does _______change the __________________ ofalleles in population!NOTrelative frequencyShuffling a deck of cardscan shuffle to producemany different hands,but doesn’t change thenumber of kings orqueens in the deck.
75EXAMPLE OF DIRECTIONAL SELECTION Beak size varies in a populationBirds with bigger beaks can feedmore easily on harder, thickershelled seeds.Suppose a food shortage causes small and medium size seeds torun low.Birds with bigger beaks would beselected for and increase in numbersin population.
80EXAMPLE OF DISRUPTIVE SELECTION Suppose bird population lives in areawhere climate change causes mediumsize seeds become scarce while largeand small seeds are still plentiful.Birds with bigger or smaller beakswould have greater fitness and thepopulation may split into TWOGROUPS. One that eats smallseeds and one that eats large seeds.
81In a small population this random change in allele frequency based on chance is called _________________GENETIC DRIFTGenetic drift can occur whena _______ groupof individualscolonizes a_____habitat.smallnew
82Individuals may carry alleles in ______________ relative frequencies than in the larger population. The population they “found” will be different from the parent population. . . not throughnatural selectionbut by _________differentchance
84In a situation in which allele frequencies remain constant HARDY-WEINBERG PRINCIPLE states that allele frequency in a population will remain __________ unless one or more ________ cause the frequency to __________.In a situation in which allele frequencies remain constant( = _________________ )populations will NOT EVOLVE!constantfactorschangeGenetic equilibrium
85Population must be large 5 CONDITIONS REQUIRED TOMAINTAIN GENETIC EQUILIBRIUMFROM GENERATION TO GENERATION1. _________________________2. _________________________3. _________________________4. _________________________5. _________________________Must be random matingPopulation must be largeNo movement in or outNo mutationsNo natural selection
87copyright cmassengale Darwin's TheoryIndividual Organisms In Nature Differ From One Another. Some Of This Variation Is InheritedOrganisms In Nature Produce More Offspring Than Can Survive, And Many Of These Offspring Do No Reproducecopyright cmassengale
88copyright cmassengale Darwin's TheoryBecause More Organisms Are Produced Than Can Survive, Members Of Each Species Must Compete For Limited ResourcesBecause Each Organism Is Unique, Each Has Different Advantages & Disadvantages In The Struggle For Existencecopyright cmassengale
89copyright cmassengale Darwin's TheoryIndividuals Best Suited To Their Environment Survive & Reproduce Successfully – Passing Their Traits To Their Offspring, maximizing their fitness.Species Change Over Time and become increasingly adapted over long periods. Natural Selection Causes Changes That May Eventually Lead To New Speciescopyright cmassengale
90copyright cmassengale Darwin's TheorySpecies Alive Today Have Descended With Modifications From Species That Lived In The PastAll Organisms On Earth Are United Into A Single Tree Of Life By Common Descentcopyright cmassengale
91Concept Map Section 15-3 Evidence of Evolution includes The fossil recordGeographic distribution of living speciesHomologous body structuresSimilarities in early developmentwhich is composed ofwhich indicateswhich implieswhich impliesPhysical remains of organismsCommon ancestral speciesSimilar genes
92PBS EVOLUTION VIDEO CLIPS Isn’t Evolution Just a Theory? QuickTime Who was Charles Darwin? How Do we Know Evolution Happens? How Does Evolution Really Work? QuickTime | Why Does Evolution Matter Now? Why is Evolution Controversial Anyway?