Bio 2B- part 3

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  • Bio 2B-
    • Fossils: remainds of organisms from many years ago, found in rocks
      • provide evidence that organisms lived ages ago.
      • 3 formations of fossils
        • replaced by minerals
          • rock substance formed on the original hard part
        • casts and impressions
          • formed in a soft material
        • preservation where no decay happens
          • decay microbes dont survive when there's no oxygen n moisture-so organism is preserved
      • EVOLVED: changed and developed.
    • Speciation: development of new species
      • occurs when ppopulation of the SAME species becomes so different that they can no longer breed.
    • Isolation: population of a species are seperated
      • separation due to physical barriers-geographically isoltes them: floods/earthquakes
        • Conditions on either side= DIFFERENT. so, DIFFERENT CHARACTERISTICS will become common due to NATURAL SELECTION
          • Eventually, the populations will have changed so much that it WONT BE ABLE TO BREED with one another--become SEPERATE SPECIES
          • population shows variation bc wide range of alleles           -invididuals better adapted to envirno=better chance of survival-breed successfully   -alleles passed on to next.
    • Extinction: organism die out
      • reasons for extinction:     1) environment changes quickly and can't eveolve quickly enough           2)new predator kills them              3)new disease               4) can't compete with new species    5)catastrophic event           6) new species develops(speciation)
    • how life came about
      • many hypothesis BUT,                       LACK of valid+reliable EVIDENCE
        • scientist believed that they were soft-bodied,and decay away completely..fossil record incomplete.
          • fossils probably destroyed by geological activity
    • Species:group of similar organisms that can repodruce to give a fertile offspring


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