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Chapter 15 notes cp Chapter 15 notes cp Presentation Transcript

  • Chapter 15Theory of Evolution
  • Theory of Evolution
  • History of Evolutionary ThoughtSection 1
  • The Idea of Evolution In the 1830s, Charles Darwinvisited the Galapagos Islandsand noted that groups ofanimals varied on each island Darwin was convinced thatorganisms had changed overtime Proposed the theory ofevolution – development ofnew types of organisms frompreexisting types of organismsover time
  • Lamarck’s Ideas on Evolution Jean Baptiste Lamarck supported the idea thatpopulations of organisms change over time His idea was the inheritance of acquiredcharacteristics No supporting evidence and has been rejected
  • Darwin’s Ideas Darwin published a book – On the Origin ofSpecies by Means of Natural Selection in 1859proposing a new theory for the way evolution tookplace Goals of the book: Present the large amount of evidence that evolution occurs Explain the variety and distribution of organisms on Earth interms of natural selection processes that are observableeveryday
  • Darwin’s Ideas
  • Descent with Modification Darwin reviewed evidence that every species –living or extinct – must have descended byreproduction from preexisting species and thatspecies must be able to change over time First to argue that all species had descendedfrom only one or a few original kinds of life
  • Evidence of Descent withModification Galapagos Islands are hometo 13 different species offinches Each has a beak that is bestadapted for a certain kind offood Darwin suspected that alldescended from one commonancestor The ancestors could haveflown from elsewhere afterthe islands were formed
  • Natural Selection Darwin proposed natural selection as themechanism for descent with modification
  • Natural Selection Overproduction More offspring can be produced than can live tomaturity Genetic Variation Within a population, individuals have different traits– some can be inherited. Occasionally, new traitsmay appear in a population.
  • Natural Selection Struggle to survive Individuals must compete with each other forresources Some variations increase and individual’s chance tosurvive and reproduce Adaptation – a trait that makes an individual successfulin its environment
  • Natural Selection Differential Reproduction Organisms with the best adaptations are most likelyto survive and reproduce Through inheritance, the adaptations will becomemore frequent in a population Populations may begin to differ as they adapt todifferent environments, even if they descended fromthe same ancestor
  • Natural Selection
  • Evidence of EvolutionSection 2
  • The Fossil Record Fossil – the remains or traces of an organismthat died long ago Among the most powerful evidence of evolution
  • The Age of Fossils Relative age – possible to tell a fossil’s age bycomparing it to that of other fossils
  • The Distribution of Fossils From the fossil record we can infer: Different organisms lived at different times Today’s organisms are different from those of thepast Fossils found closer together are more like eachother than ones found further away Where and when different organisms existed
  • Transitional Species The fossil recordshows that specieshave differed in agradual sequence offorms over time
  • Biogeography Biogeography – the study of the locations oforganisms around the world Darwin and Wallace observed species thatseemed closely related but were adapted todifferent environments in nearby regions They also observed animals that seemedunrelated but had similar adaptations to similarenvironments in regions that were far apart
  • Anatomy and Embryology Anatomy – the study of the body structure oforganisms Embryology – the study of how organismsdevelop As generations passed, different populations ofdescendants adapted to different environments Homologous structures- structures that occur indifferent species and that originated by heredityfrom a structure in the most recent commonancestor of the species Analogous structures – closely related functionsbut do not derive from the same ancestral
  • Anatomy and Embryology
  • Anatomy and Embryology Vestigial Structures– structures that seemto serve no functionbut that resemblestructures withfunctional roles inrelated organisms Development ofanimal embryos –some stages ofvertebrate embryodevelopment are veryalike
  • Biological Molecules In all species, DNA and RNA are the molecularbasis for inheritance of traits Scientists can compare the DNA, RNA, andproteins from many different organisms and lookfor similarities and differences The greater number of similarities, the moreclosely the species are related through a commonancestor
  • Evolution in ActionSection 3
  • Convergent Evolution Convergent Evolution – the process by whichdifferent species evolve similar traits Example: Caribbean Anole Lizards
  • Convergent Evolution Many different body types on different islands anddifferent species have the same body types Lizards that live on tree trunks have stocky bodiesand long legs Lizards that live on slender twigs have thin bodies,short legs and tails, and large toe pads Lizards that live in the grass are slender and havevery long tails How did all of this happen?
  • Convergent Evolution Each species evolved independently on eachisland from different ancestor species
  • Divergent Evolution Divergent evolution – Process in whichdescendants of a single ancestor diversify intospecies that each fit different parts of theenvironment Ex: Lizards with genes for large toe pads and shortlegs ran so slowly on the trunk and ground thatpredators often caught them
  • Artificial Selection Artificial Selection –process when ahuman breederchooses individualsthat will parent thenext generation
  • Coevolution Coevolution – when two or more species haveevolved adaptations to each other’s influence Ex: Humans develop and use antibiotics to killbacteria, many populations of bacteria have evolvedto resist the effects of antibiotics