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Unit 7 evolution 1
 

Unit 7 evolution 1

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    Unit 7 evolution 1 Unit 7 evolution 1 Presentation Transcript

    • UNIT 7 - Evolution“TO BE OR NOT TO BE”
    • EVOLUTION Definition:  evolution is any change in the frequency of an allele in a gene pool  Theory – a collection of carefully reasoned and tested hypothesis about how evolutionary change occurred
    • I. Ancient Earth A. Atmospheric Conditions (pg 342)  1. Gases (notice no oxygen) • Large %  Carbon dioxide (CO2), Nitrogen (N2), Water vapor • Small %  Methane(CH4), Ammonia(NH3), Hydrogen Sulfide (H2S)  2. Miller -Urey Experiment • Synthesized complex organic molecules by mixing and electrically stimulating a mixture gases (pg 344) • Urea, acetic acid, amino acids, lactic acid, adenine, ATP were produced
    • I. Ancient Earth 3. Other Experiments  No oxygen in mixture allowed the formation of • Polypeptides - amino acids linked together
    • I. Ancient Earth B. The First Cells –  3.5 bya - anaerobic, prokaryotic (like today’s bacteria), heterotrophic, high competition for food  3.4 bya – autotrophic, probably photosynthesis with H2S instead of water  2.2 bya – modern photosynthesis, use H2O, releasing O2 into the atmosphere, ozone layer formed  1.5 bya – eukaryotic cells, sexual reproduction, increased genetic diversity  1.3 bya – multicellular organisms
    • I. Ancient Earth C. Age of the Earth  1. Formation of Earth - 4.5 billions years ago  2. Relative dating - geologic time scale (pg 23 UP)  3. Absolute dating - half-life • Half-life = time it takes for 1/2 of a radioactive substance to decay (breakdown) • Carbon-14 1/2 life = 5770 years • Potassium-40 1/2 life = 1.3 billion years
    • II. Evolution D. Evidence for Evolution  1. Fossil record (pg 278) • Fossils are any preserved remains or evidence of an ancient organism • Examples - insects in amber, frozen mammoth, petrified wood or bones, imprints in rock • Not complete - many organisms do not become fossilized • Not all specimens are the same quality • Record does indicate what did live at different times • Record does show that living things changed with changes on the Earth
    • II. Evolution D. Evidence for Evolution  2. Living organisms • Embryology - development of embryos very similar in different species • Body Structure  Homologous structures - bones in the legs and arms of vertebrates are very similar in structure but not always function(lab 38)  Vestigial organs - organs that remain in an organism but seem to have no obvious function • leg bones in pythons, muscles that move the ears in humans, appendix in humans • Biochemistry - similar chemicals found in living things, DNA sequence, blood antigens (lab 28)
    • III.Theories of Evolution A. Lamarck  1. Desire to change • Animals changed in structure because of a desire to improve • Giraffe’s necks got longer because they stretched to get the leaves at the top branches,  2. Use and Disuse • Use it or lose it - through disuse things would be lost  3. Acquired characteristics were inherited • Any changes in the adult were passed on to the offspring • Example - stretched necks of adult giraffes were inherited by young
    • Darwin
    • III.Theories of Evolution B. Darwin  1. Overproduction of offspring • Organisms tend to produce more offspring than needed to replace numbers  2. Struggle for existence • Competition for resources is always present • Predation always present  3. Variations in populations exist • Differences in structure exist at birth not acquired • These variations are inherited from the parents
    • III.Theories of Evolution C. Natural Selection  1. Definition - the organisms that are best suited for the present environmental conditions will survive to reproduce therefore passing on their characteristics to their offspring • “Survival of the Fittest” - not necessarily the strongest or fastest.  2. Conditions that help • Mutation - source of variation in genes • Gene flow - genes moving between populations  3. Adaptations • - traits that survive from one generation to the next  4. Example - Peppered Moth / industrial revolution in England • Two phenotypes for moth = Black and speckled • When the bark of the trees got discolored the population changed from mostly speckled to mostly black
    • Span worm Wandering leaf insect Bombardier beetle Foul-tasting monarch butterflyPoison dart frog Viceroy butterfly mimics When touched, the Hind wings of io moth snake caterpillar monarch butterfly resemble eyes of a changes shape to look much larger animal like the head of a snake Figure 8-11 Page 177 Slide 18
    • IV. Types of Evolution A.Microevolution - changes that take place within a single species to form variations in populations. B.Macroevolution - changes that have taken place in a species that leads to two or more different species (common descent)
    • IV.Types of Macroevolution 1. Gradualism  One species gradually changes into a new species 2. Divergent Evolution or Speciation  a. Definition - the development of two or more species from a common ancestral species • Adaptive radiation - a habitat opens up that permits many new niches to be occupied allowing many variations to survive.  b. Processes that need to occur • Geographical isolation - members of a species is separated from others due to physical barriers  Mountain ranges, oceans, canyons • Reproductive Isolation - species are separated by the ability to reproduce  Mating behaviors, physical structures, genetic make-up
    • IV.Types of Macroevolution 3. Punctuated equilibria  Tempo of speciation: gradual vs. divergence in rapid bursts; Eldredge and Gould (1972); helped explain the non- gradual appearance of species in the fossil record
    • IV.Types of Macroevolution 4. Convergent Evolution  a. Definition - when two separate species develop similar adaptations (phenotypes) through different evolutionary trees  b. Examples • Sharks and dolphins (pg 21 in UP) • mimicry
    • V.Human Evolution Pages 34,35,61 in UP