Unit 8 evolution for moodle
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Unit 8 evolution for moodle






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  • Why are really old Fossils are hard to come by? -The remains decay. -Special circumstance embed bones into rocks or images of animals like the Trilobites I recommend visiting the Museum of Science and Industry. How would you date fossils from rocks?
  • What is an example of a homologous Structure? Birds wing to mans arm, or horse leg
  • Analagous- similar to the word analogy: A comparison between two different situations that have something in common
  • Does anyone have any examples of selective breeding? Tell the class about Cats I am waiting until they breed cats they have less of a chemical that causes allergic reactions because I love cats, but allergic to them

Unit 8 evolution for moodle Unit 8 evolution for moodle Presentation Transcript

  • Unit 8 Evolution
  • What is Evolution? A well-supported scientific theory stating that organisms change over time
  • Evidence in stone Preserved remains of a once living organism is called a FOSSIL Fossil evidence supported that organisms changed gradually
  • Anatomical Evidence Comparative Anatomy: study of similarities and differences between organisms Homologous Structures Analogous Structures Vestigial Organs
  • Homologous StructuresAs similar organisms adapt to differentenvironments, the function of their appendageschanged A bird’s arms became wings to flap A human’s arm is used to pick-up, carry, grasp, etc… A horse’s arm became a fore-leg to run on
  • Analogous Structures Different organisms began living in similar environments, their appendages evolved to perform the same function A butterfly has wings to fly that are made from an exoskeleton A sparrow has wings to fly that have an endoskeleton Butterfly Bird
  • Vestigial Structures Structures which remain in organisms but have no obvious function Leg bones in snakes and whales Appendix in humans ** Ear muscles in humans
  • Comparative EmbryologyExamining theembryos oforganismsOrganisms withsimilar embryos arethought to be moreclosely related
  • Biochemical Evidence(aka Molecular Biology)Comparison of the amino acid and DNAsequences Chimp and human hemoglobin are VERY similar
  • Genetic Evidence DNA passes on traits When mutations occur the genes and chromosomes can change Humans have imposed change through selective breeding The higher the percentage of similarities the closer the relationship between two organisms
  • Jean Baptiste de Lamark First to recognize that organisms change Published his hypotheses in 1809 Theory was disproved!
  • Jean Baptiste de Lamark3 Key Assumptions: Desire to Change: organisms have an inborn urge to better themselves Law of Use and Disuse: body parts that are used will develop; those not used will become smaller/disappear Inheritance of Acquired Characteristics: organisms pass on traits acquired during their lifetime
  • Charles DarwinCredited for the theory of evolutionHMS Beagle sailed in 1831 – Galapagos IslandsPublished Origin of Species in 1858
  • Darwin’s Observations Observed tortoises, iguanas, and finches The islands had different climates and vegetation The animals were similar… but had noticeable differences WHY?
  • Darwin’s AssumptionsVariations Differences among members of the same speciesStruggle for Existence Predation and competitionOverproduction More offspring are produced than will surviveSurvival of the Fittest (Natural Selection) Individuals best suited for the environment will survive, reproduce, and pass on traits to their offspringDescent with Modification Principle that species change but descend from common ancestors
  • Lamark’s Giraffes
  • Darwin’s Theory of Natural Selection Variations help members of a species to survive in a given environment The environment selects the beneficial adaptation and over time this trait will become more prevelant
  • Darwin’s Finches
  • Fossil FormationWater carries small Dead organisms are buried The preserved remainsrock particles to lakes by layers of sediment, may later be discoveredand seas which forms new rock and studied.
  • Fossil RecordPreserved remains of a once livingorganism is called a FOSSIL IE: amber, sedimentary rock, tar, and iceFossil record is incomplete
  • Relative Dating Used to ESTIMATE the age of fossils Older fossils are in deeper layers of rock
  • Genes and EvolutionIn terms of genetics, evolution is the change infrequency of alleles in a population’s genepoolNatural selection leads to change in gene frequencyMolecular clocks use mutation rates to estimatehow recent a common ancestor was
  • Hox GenesGenes which control an organism’s basic body plan Anterior/posterior ends Limbs, wings
  • Genetic DriftChanges in the genepool of a smallpopulation due torandom chance ex: small group colonizes a new habitat – founder effect
  • SpeciationGradualism – change in speciesis slow and steadyPunctuated Equilibrium – longperiods of stability followed byshort periods of rapid change
  • Punctuated Equilibrium vs.Gradualism
  • Speciation – Isolating Mechanisms For new species to form, reproductive isolation needs to occur Organisms don’t interbreed - gene pools become separate - Behavioral, Geographic, Temporal
  • Adaptive RadiationA single species evolves into many speciesOften occurs when a niche opens up
  • Convergent EvolutionOrganisms come toresemble one anotherbut evolveddifferentlyAnalogous structures!Examples: Dolphins and sharks Marsupials and mammals
  • CoevolutionOrganisms with close ecological relationshipsevolve together Pollinators and flowers
  • Ancient EarthAtmosphere was composed of gases: CO2, N2, water vapor, CH4, H2S No O2Earth formed ~4.6 billion years ago
  • First Organic Molecules 1950’s Miller & Urey reproduced conditions of ancient Earth Electric sparks simulated lightning Amino acids began to form
  • First Cell
  • Oxygen Accumulation inAtmosphere
  • What is a Primate?Binocular VisionDeveloped brainLong fingers & toesRotating shoulders
  • What makes us Human?Characteristics ofthe Hominine Family Bipedal Opposable Thumbs Larger Brains
  • Did we evolve from chimps?
  • Hominine Evolution Ardipithecus ramedus “Ardi”, 4.4 mya Australopithecus afarensis “Lucy”, 3.2 mya Homo habilis “handy man”, ≈ 2 mya Used tools, first of the genus Homo Homo erectus, “Java Man”, ≈ 1.6 mya 1st to use fire Homo neanderthalensis ≈ 200,000 years ago Homo sapien Modern Human ≈ 100,000 years ago
  • Family Tree or Bush?