Evolution.ppt nelson

4,200 views

Published on

Published in: Technology
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
4,200
On SlideShare
0
From Embeds
0
Number of Embeds
1,778
Actions
Shares
0
Downloads
49
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Evolution.ppt nelson

  1. 1. History of EvolutionaryHistory of Evolutionary ThoughtThought • SpeciesSpecies- a group of organisms that can- a group of organisms that can iinterbreednterbreed and produceand produce fertile offspringfertile offspring.. • Before 1850Before 1850,, most people believedmost people believed …… – The earth was formed by supernatural eventsThe earth was formed by supernatural events – Earth never changes.Earth never changes. – The earth was only a few thousand years old.The earth was only a few thousand years old. – Each species was made by a divine creator.Each species was made by a divine creator. – Each species was made to fit its environment.Each species was made to fit its environment. – Species never changed and did not go extinct.Species never changed and did not go extinct.
  2. 2. Charles DarwinCharles Darwin • 02/12/1809 – 4/19/188202/12/1809 – 4/19/1882 • At age of 22, sailed onAt age of 22, sailed on “HMS Beagle” to“HMS Beagle” to Galapagos islandsGalapagos islands • Believed God createdBelieved God created each species to match itseach species to match its habitat and a specieshabitat and a species never changed.never changed.
  3. 3. Charles Darwin cont.Charles Darwin cont. • Five year journey, heFive year journey, he made observationsmade observations and recorded them inand recorded them in a journal.a journal. • Darwin began toDarwin began to doubt that speciesdoubt that species remained “constant.”remained “constant.”
  4. 4. James Hutton and CharlesJames Hutton and Charles LyellLyell • Founders modernFounders modern geology.geology. • The crust of the earthThe crust of the earth has been slowly changinghas been slowly changing over time.over time. • Some of earth’sSome of earth’s formations have takenformations have taken millions of years to form.millions of years to form. • The earth is older thanThe earth is older than what people thought.what people thought.
  5. 5. George CuvierGeorge Cuvier • Species can go extinct.Species can go extinct. • Proved this studyingProved this studying fossils.fossils. • Ex.) Mammoth fossilsEx.) Mammoth fossils • The earths crust isThe earths crust is “layered” with fossils.“layered” with fossils. • Deeper crust = olderDeeper crust = older fossilsfossils
  6. 6. Jean Baptiste LamarckJean Baptiste Lamarck • Species change overSpecies change over time.time. • Species can “acquire”Species can “acquire” traits in their lifetime.traits in their lifetime. • Ex.) Big muscles.Ex.) Big muscles. • These traits can beThese traits can be passed to offspring.passed to offspring. • Right idea, wrongRight idea, wrong explanation.explanation.
  7. 7. Alfred Russell WallaceAlfred Russell Wallace • Studied differentStudied different species around thespecies around the world.world. • There is a constantThere is a constant struggle for food.struggle for food. • Weaker individualsWeaker individuals will die out.will die out. • Survival of the fittest.Survival of the fittest.
  8. 8. Thomas MalthusThomas Malthus • Applied Wallace’sApplied Wallace’s concept to humans livingconcept to humans living in London.in London. • Population growth wasPopulation growth was very high.very high. • People were dying due toPeople were dying due to starvation and disease.starvation and disease. • The environment cannotThe environment cannot support everyone.support everyone. • This applies to allThis applies to all species.species.
  9. 9. Lamark Species do change Malthus Wallace Lyell Earth old enough for change to occur, causing Darwin to question if life could change as well? Population ideas apply to all species… Darwin felt ideas applied even more directly to plants and animals Sent copy of his essay to Darwin  Darwin realized these were same ideas he had
  10. 10. Charles DarwinCharles Darwin • In 1859, Darwin publishedIn 1859, Darwin published “The Origin of Species.”“The Origin of Species.”
  11. 11. Major points of Darwin’s book:Major points of Darwin’s book: • Organisms have traits that help themOrganisms have traits that help them survive.survive. • Species do change over time.Species do change over time. • These gradual changes may causeThese gradual changes may cause one species to change into newone species to change into new species.species. • African apes are close geneticAfrican apes are close genetic relatives of modern humans.relatives of modern humans.
  12. 12. Darwin’s Theory –Darwin’s Theory – Evolution by Natural SelectionEvolution by Natural Selection
  13. 13. What causes evolution?What causes evolution? • EvolutionEvolution is the GENETIC change in membersis the GENETIC change in members of a species over time.of a species over time. • Darwin’s most important insight was thatDarwin’s most important insight was that members of a species vary.members of a species vary. • Ex) LivestockEx) Livestock • Farmers use variation inFarmers use variation in artificial selectionartificial selection or “selective breeding”or “selective breeding” • Nature provides the variation, humans selectNature provides the variation, humans select and breed useful variations to improve crops,and breed useful variations to improve crops, etc.etc. • Later, Darwin stated reason for why species inLater, Darwin stated reason for why species in nature change…nature change… • Called “Called “natural selectionnatural selection ” …” …
  14. 14. Natural SelectionNatural Selection • Natural Selection is the “process” thatNatural Selection is the “process” that drives evolution.drives evolution. • Process by which individuals that areProcess by which individuals that are better suited to their environmentbetter suited to their environment survive and reproduce mostsurvive and reproduce most successfully.successfully.
  15. 15. Natural SelectionNatural Selection 1.) Every species contains1.) Every species contains varietyvariety.. Causes?Causes? 2.) Living things face a2.) Living things face a constant struggleconstant struggle forfor existence.existence. Why?Why? 3.) Only individuals that survive can reproduce.3.) Only individuals that survive can reproduce. ““Survival of the fittest”?Survival of the fittest”? AdaptationAdaptation?? 4.) Results in changes in the4.) Results in changes in the gene poolgene pool.. How is genetic change measured?How is genetic change measured? 5.)5.) Entire speciesEntire species is now better suited foris now better suited for survival.survival. HOW? If not?HOW? If not?
  16. 16. Darwin’s Theory –Darwin’s Theory – Evolution by Natural SelectionEvolution by Natural Selection
  17. 17. Natural Selection (Review)Natural Selection (Review) • VariationVariation (caused by genetics)=(caused by genetics)= neck lengthneck length • More individuals than can survive=More individuals than can survive= competition forcompetition for leaves in treesleaves in trees • Members with bestMembers with best adaptationadaptation will survive andwill survive and reproduce –reproduce – long necklong neck • Results inResults in genetic changegenetic change== frequency long neckfrequency long neck allele increasing and short neck allele decreasingallele increasing and short neck allele decreasing • Results in next generation of the species beingResults in next generation of the species being “genetically better” than the previous generation-“genetically better” than the previous generation- number of giraffes with long neck more prevalentnumber of giraffes with long neck more prevalent in populationin population
  18. 18. Evolution and NaturalEvolution and Natural SelectionSelection “Misconceptions”“Misconceptions” • Q: Why is variation important?Q: Why is variation important? • A: Variation is key because the environment anA: Variation is key because the environment an organism lives in is constantly changingorganism lives in is constantly changing -ex) England- factories/pollution-ex) England- factories/pollution -What if amongst the moths there was no-What if amongst the moths there was no variation… only peppered no dark…variation… only peppered no dark… -Result might have been…-Result might have been… EXTINCTIONEXTINCTION
  19. 19. Evolution and NaturalEvolution and Natural SelectionSelection “Misconceptions”“Misconceptions” • Q: What is an adaptation?Q: What is an adaptation? -adaptation is-adaptation is NOTNOT a process by which organisma process by which organism “changes” to survive“changes” to survive -It is-It is incorrectincorrect to say… “When the environmentto say… “When the environment changed the dark moths were the best at adapting andchanged the dark moths were the best at adapting and remained hidden from the birds.”remained hidden from the birds.” -It is also-It is also incorrectincorrect to say… “The moth populationto say… “The moth population adapted to the environment after the pollution increasedadapted to the environment after the pollution increased and thus lived.”and thus lived.”
  20. 20. Evolution and NaturalEvolution and Natural SelectionSelection “Misconceptions”“Misconceptions” • A:A: AnAn adaptation is a trait an organism is bornadaptation is a trait an organism is born with thatwith that becausebecause of what the environment isof what the environment is like it increases the organism’s chances oflike it increases the organism’s chances of survivingsurviving -peppered moths could not consciously change-peppered moths could not consciously change their color from peppered to darktheir color from peppered to dark -this is what you are implying if you write “the-this is what you are implying if you write “the dark moths were the best at adapting to …”dark moths were the best at adapting to …” -NO organism can change its genetic traits-NO organism can change its genetic traits (DNA)(DNA)
  21. 21. Evolution and Natural SelectionEvolution and Natural Selection “Misconceptions”“Misconceptions” • Q: Definition ofQ: Definition of evolutionevolution is- genetic change inis- genetic change in a species over time… What does genetica species over time… What does genetic change refer to?change refer to? -It is understood that an organism can NOT change its-It is understood that an organism can NOT change its DNA …so how does genetic change apply…DNA …so how does genetic change apply… • A: Genetic change means changes in allele frequency inA: Genetic change means changes in allele frequency in thethe gene poolgene pool, which lead to changes in genotypic, which lead to changes in genotypic frequency, and then changes in phenotypic frequency asfrequency, and then changes in phenotypic frequency as wellwell
  22. 22. Evolution and NaturalEvolution and Natural SelectionSelection “Misconceptions”“Misconceptions” • Q: Entire species is better suited …Q: Entire species is better suited … means…means… • A: “TheA: “The entire populationentire population of the species is nowof the species is now better suited for survival.”better suited for survival.” • Q: How would this apply to the pepperedQ: How would this apply to the peppered moths?moths? • A: The species of moths is now better suited forA: The species of moths is now better suited for survival because the population consists of mostlysurvival because the population consists of mostly dark moths.dark moths.
  23. 23. Evolution and NaturalEvolution and Natural SelectionSelection • The definition of evolution isThe definition of evolution is …… -genetic change amongst members of a species-genetic change amongst members of a species -this is happening in the population in terms of-this is happening in the population in terms of the alleles causing changes in both genotypicthe alleles causing changes in both genotypic and phenotypic frequencies…and phenotypic frequencies…
  24. 24. Evolution and NaturalEvolution and Natural SelectionSelection • We can describe the genetic change amongst theWe can describe the genetic change amongst the population two ways…population two ways… • Directional selection vs. balancingDirectional selection vs. balancing selectionselection • Both terms describe how the allele frequencies areBoth terms describe how the allele frequencies are changing as a result of natural selection…changing as a result of natural selection…
  25. 25. Evolution of Peppered Moths… Genetic Change Amongst the Peppered Moth Population 0 0.2 0.4 0.6 0.8 1 1.2 Year 1 Year 3 Year 5 Year 7 Year 9 Year AlleleFrequencies p q
  26. 26. Evolution of PepperedEvolution of Peppered Moths…Moths… • Frequency of the dominant allele (p orFrequency of the dominant allele (p or peppered)peppered) decreaseddecreased • Frequency of the recessive allele (q orFrequency of the recessive allele (q or dark)dark) increasedincreased • This isThis is directional selectiondirectional selection
  27. 27. Directional SelectionDirectional Selection • Frequency of an allele isFrequency of an allele is pushed in one directionpushed in one direction without oppositionwithout opposition
  28. 28. Sickle Cell Anemia: TheSickle Cell Anemia: The PuzzlePuzzle • Recessive diseaseRecessive disease originated in Africaoriginated in Africa • AfricaAfrica 1/100 aa1/100 aa • United StatesUnited States 1/500 aa1/500 aa • Why has naturalWhy has natural selection not actedselection not acted against the sickle cellagainst the sickle cell allele (a) in Africa toallele (a) in Africa to reduce its frequency?reduce its frequency?
  29. 29. Genetic Change Amongst the African Population 0 0.2 0.4 0.6 0.8 1 1.2 1 2 3 4 5 Year AlleleFrequeny p q
  30. 30. Balancing SelectionBalancing Selection • Two opposite forces affect the allele in aTwo opposite forces affect the allele in a populationpopulation • Allele frequency may vary year to year, butAllele frequency may vary year to year, but over time usually remains same (value)over time usually remains same (value) ex) sickle cell allele (aa) – lethal - death by sickleex) sickle cell allele (aa) – lethal - death by sickle cell =cell = decreasedecrease ex) sickle cell allele (a) – favorable - (Aa) resistant toex) sickle cell allele (a) – favorable - (Aa) resistant to malaria =malaria = increaseincrease ex) no sickle cell allele (AA) – lethal - death byex) no sickle cell allele (AA) – lethal - death by malaria =malaria = decreasedecrease
  31. 31. How Species Form?How Species Form? • Natural selection favors variationsNatural selection favors variations that increases a species survival.that increases a species survival. • If environment changes, naturalIf environment changes, natural selection will occur.selection will occur. • Can members of a species changeCan members of a species change enough to form a new species?enough to form a new species? • SpeciationSpeciation- generation of a new- generation of a new speciesspecies
  32. 32. How Species Form?How Species Form? • Ecological Races (subspecies)Ecological Races (subspecies) – Populations of the same species thatPopulations of the same species that differ genetically because they havediffer genetically because they have adapted to different living conditions.adapted to different living conditions. – Still members of same species.Still members of same species.
  33. 33. Why might members ofWhy might members of same species be separated?same species be separated? • Different groups of subspecies mayDifferent groups of subspecies may become isolated from each other.become isolated from each other. • Isolation makes it difficult for membersIsolation makes it difficult for members of the same species to mate.of the same species to mate. • Geographic IsolationGeographic Isolation • Populations separated into differentPopulations separated into different environments due to geographicalenvironments due to geographical features (mountains, canyons, bodiesfeatures (mountains, canyons, bodies of water, etc.)of water, etc.)
  34. 34. Speciation cont.Speciation cont. • When geographical isolation preventsWhen geographical isolation prevents interbreeding for long periods of time,interbreeding for long periods of time, populations in different places becomepopulations in different places become increasingly different due to differentincreasingly different due to different environments.environments. • Eventually if the groups can no longerEventually if the groups can no longer mate and create fertile offspring, theymate and create fertile offspring, they will be considered separate species.will be considered separate species.
  35. 35. MacroevolutionMacroevolution • Evolutionary relationships on a “large scale”Evolutionary relationships on a “large scale” • Scientists attempt to explainScientists attempt to explain diversification of lifediversification of life • Scientists attempt at determining how livingScientists attempt at determining how living organisms on Earth are related to each otherorganisms on Earth are related to each other • ““Common Ancestor”Common Ancestor” • Ex) Charles Darwin said…Ex) Charles Darwin said… ““Humans and apes shared a common ancestor”Humans and apes shared a common ancestor” ““Modern day whales had a distant ancestor thatModern day whales had a distant ancestor that lived on land and walked on four limbs”lived on land and walked on four limbs”
  36. 36. Evidence of EvolutionEvidence of Evolution • Fossil EvidenceFossil Evidence • Structural EvidenceStructural Evidence • Developmental EvidenceDevelopmental Evidence • DNA EvidenceDNA Evidence
  37. 37. What is a fossil?What is a fossil? • Any traces of dead organisms.Any traces of dead organisms. • Organism must be buried byOrganism must be buried by sediment. Usually happens insediment. Usually happens in swamps, mud, tar pits, or the oceanswamps, mud, tar pits, or the ocean bottom.bottom. • ““Hard stuff” fossilizes.Hard stuff” fossilizes.
  38. 38. What can fossils tell us?What can fossils tell us? • A glimpse into the history of an organismsA glimpse into the history of an organisms past.past. • Transitional species = “intermediateTransitional species = “intermediate forms”forms” • Ex.) Whale evolutionEx.) Whale evolution
  39. 39. Structural EvidenceStructural Evidence • Comparing the way two organisms are putComparing the way two organisms are put together to determine if related or sharetogether to determine if related or share common ancestor.common ancestor. • Homologous StructuresHomologous Structures : structures that are: structures that are similar in structure differ in function.similar in structure differ in function.
  40. 40. Structural Evidence cont.Structural Evidence cont. • Vestigial structuresVestigial structures : Structures reduced in: Structures reduced in size and have no present function; “remants ofsize and have no present function; “remants of organism’s past”organism’s past”
  41. 41. Developmental EvidenceDevelopmental Evidence • Compares embryosCompares embryos of different species to determineof different species to determine how closely organisms are related and whether or nothow closely organisms are related and whether or not might share a common ancestor.might share a common ancestor. • Longer early stages of development are similar betweenLonger early stages of development are similar between organisms= more closely relatedorganisms= more closely related
  42. 42. Fish Salamander Fish Tortoise Chicken Rabbit HumanRabbit
  43. 43. DNA EvidenceDNA Evidence • DNA evidence supports the other three.DNA evidence supports the other three. • If species change over time, their DNA willIf species change over time, their DNA will also change.also change. • Similar organisms=similar DNASimilar organisms=similar DNA sequencessequences • More similar DNA = more closely related.More similar DNA = more closely related.

×