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The Rate of Evolution and Extinction

The Rate of Evolution and Extinction. What affects how fast orgs evolve? What leads to extinction?. Change is Everything!. Change in environment = Change in species! Failure to adapt to changes = possible extinction . Rate of Evolution What affects how fast a species evolves?.

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The Rate of Evolution and Extinction

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  1. The Rate of Evolution and Extinction What affects how fast orgs evolve? What leads to extinction?

  2. Change is Everything! • Change in environment = Change in species! • Failure to adapt to changes = possible extinction 

  3. Rate of EvolutionWhat affects how fast a species evolves? • Rate of environmental change • Rate of reproduction

  4. Rate of Environmental Change • Rapid environmental change = rapid change in species • Rapid change • Ex. Modern horse: many changes over past million years • Slow change • Ex. Horseshoe crab: nearly identical to ancestors from 300 mya

  5. Rate of Reproduction • The # of offspring produced can tell us how quickly a species can evolve • Few offspring = longer life = slow evolution • Ex. Humans, elephants • Many offspring = shorter life = quicker evolution • Ex. Bacteria, single celled orgs, fish

  6. Antibiotic Resistance

  7. Let’s look at bacteria • Reproduce very quickly • Millions exposed to antibiotic • Very good chance a few will have resistantgene due to random mutation • These will live, THEN pass on resistance • Pretty soon, large pop’n that have this resistance • If same antibiotic used again, will increase resistance • Soon, a SUPER STRAIN of this bacteria has evolved Brain Pop link

  8. Lesson learned: • Only use antibiotics when necessary • Many strains are resistant to penicillin, the first antibiotic used • Humans are creating Super Strains with continued misuse of antibiotics • Similar occurrences with insects and insecticides

  9. What causes extinction? • Death rate higher than birth rate • Usually due to rapid env. changes • These env. changes cause major drop in pop’n size if species cannot adapt • Variation drops! • Less variation to pass on • Offspring essentially inbreeding, variation drops even more NO VARIATION = NO ADAPTIVE VALUE = EXTINCTION

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