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Cpbio ch 13 evolution

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high school college prep biology evolution power point

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Cpbio ch 13 evolution

  1. 1. EVOLUTION!!!
  2. 2. Charles Darwin, 1808-1882WHAT ABOUT HIM???born into a wealthy familymedical school drop-out - thought surgerywas “brutal”his father pushed him into becoming aclergyman and dropped-out of this as welleventually followed his interests in ecology,geology and taxidermyauthor of “On the Origin of Species” - 1859,provided evidence for evolution by naturalselection
  3. 3. SOME OF DARWIN’SINFLUENCES…Charles Lyell, 1797-1875 - “Principles ofGeology”, described landforms as the result ofgradual processes over time (Darwin sawevidence of this on his voyage - bands of coralfragments in volcanic rock)John Henslow, 1796-1861 - botanist/geologist,Darwin’s mentor
  4. 4. SOME OF DARWIN’SINFLUENCES…Thomas Malthus, 1766-1834 - “An Essay onthe Principle of Population”, proposed that ifthe human population continues to grow“unchecked” it would soon reach carryingcapacity…then what???"In October 1838, that is, fifteen months after I had begun my systematic inquiry,I happened to read for amusement Malthus on Population, and being well preparedto appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me thatunder these circumstances favourable variations would tend to be preserved, andunfavourable ones to be destroyed. The results of this would be the formation of anew species. Here, then I had at last got a theory by which to work".Charles Darwin, from his autobiography. (1876)
  5. 5. DARWIN’S VOYAGEwas selected as an unpaid geologist/naturalistvoyaged on the HMS Beaglepurpose of voyage was to chart the coastline ofSouth America over 2 yearsDarwin collected fossils and living organismsand took many notesunfortunately…he was seasick for most of thetrip
  6. 6. WHAT DID HE SEE IN THEGALAPAGOS ISLANDS???Galapagos Islands - volcanic islands west ofEcuador in the Pacific Ocean (16 islands - 5inhabited), some are still formingobserved birds (later determined to be finches)- similar in appearance with differing beakssince these were islands, all of the birds wereassumed to have one common ancestoreach bird was adapted to eating a particularfood - seeds, insects, etc.
  7. 7. DARWIN’S FINCHES
  8. 8. EVOLUTION BY NATURALSELECTION???Darwins theory (yes, you need to know this!):within a given species, more individuals are produced thancan survive due to limited resources (food, shelter, mates)as a result, there is a struggle for existence/competition forlimited resourcesindividuals within a species show variation - no twoindividuals are exactly alikethose with advantageous traits have a greater chance ofsurvival, and therefore of reproducingindividuals produce offspring that tend to resemble theirparents (inheritance)advantageous traits that promote survival are inherited byoffspring, so individuals possessing those traits will becomemore common in the population over successive generationsbecause they are more likely than individuals not possessingthose traits to survive and reproduce
  9. 9. HOW DO ORGANISMSACQUIREADVANTAGEOUSTRAITS???GOOD QUESTION!!!
  10. 10. WHAT IS EVOLUTION BYNATURAL SELECTION???Simply stated:in nature individuals compete for limitedresources and based on those resources, natureselects the best suited for the environment =natural selectionlet’s look at an example…and another…and another…and another…
  11. 11. INDUSTRIALMELANISM
  12. 12. More on Darwin…Natural selection…less wordymore organisms are produced than can survivethere is competition for resourcesthose with favorable traits (depending on whatthe competition is over) win the resource(s)these are the organisms that survive andreproduce (and make more like themselves)favorable traits are the result of differencesbetween organismsdifferences are the result of random mutations
  13. 13. TERMS TO KNOWadaptation - change in a species that makes itbetter suited for its environmentnatural selection - “nature” selects organisms withbetter suited traits to survive and reproduce, overtime organisms become better adaptedisolation leads to the development of new species -when organisms are isolated and cannot breed,they become more different over time
  14. 14. EVIDENCE FOREVOLUTION1. fossils - show a pattern of development, allorganisms evolved from earlier life formsFYI…there are few “missing links” or intermediateforms or transitional speciesarchaeopteryx is one of the few “missing links” - ithas both reptile and bird-like features
  15. 15. 2. biological molecules - comparing proteins andnucleic acid sequences can reveal a commonancestorfor example - comparing differences in hemoglobin (aprotein that carries oxygen in your bloodstream) -more distant ancestors have more differences
  16. 16. 3. comparing anatomy can reveal similaritieshomologous structures -similar structures, althoughthey may have different functions/are adapted todifferent environments
  17. 17. analogous structures – similar function, butoccur in unrelated species adapting to similarenvironments
  18. 18. 4. biogeography – studies locations of organismsaround the world closely related organisms can be adapted todifferent environments that are nearby (ex.– Darwin’s finches) unrelated organisms can have similaradaptations to similar environments thatare far apart (ex. – Australia’s mammalsthat resemble mammals in similarenvironments but are unlike in that theyare all marsupials)
  19. 19. 5. vestigial structures - structures that have lessimportant/no function as compared to relatedorganismsfor example - the human tailbone (coccyx), earmuscles and the gene to make vitamin Cother vestigial structures - baleen whale pelvis andfemur, splint in horses, pelvis and femur in somesnakes
  20. 20. 6. comparing embryos - early in developmentmany organisms share similar characteristics
  21. 21. phylogeny – puts evidence together to showrelationships among organisms
  22. 22. GRADUALISM VERSUSPUNCTUATEDEQUILIBRIUMgradualism - evolution occurs slowly over a longperiod of time, organism changes many timesfor example – human evolution…many smallchanges occurred…larger brain size, bipedalismpunctuated equilibrium - major environmentalchanges may cause evolution to occur in spurts,rapid change followed by periods of no changefor example – species that show few “transitionalspecies” such as T. rex

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