The Rate of Evolution and Extinction

The Rate of Evolution and ExtinctionWhat 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 EvolutionWhat affects how fast a species evolves?Rate of environmental changeRate of reproduction

Rate of Environmental ChangeRapid environmental change = rapid change in speciesRapid changeEx. Modern horse: many changes over past million yearsSlow changeEx. Horseshoe crab: nearly identical to ancestors from 300 mya

Rate of ReproductionThe # of offspring produced can tell us how quickly a species can evolveFew offspring = longer life = slow evolutionEx. Humans, elephantsMany offspring = shorter life = quicker evolutionEx. Bacteria, single celled orgs, fish

Antibiotic Resistance

Lets look at bacteriaReproduce very quicklyMillions exposed to antibioticVery good chance a few will have resistant gene due to random mutationThese will live, THEN pass on resistancePretty soon, large popn that have this resistanceIf same antibiotic used again, will increase resistanceSoon, a SUPER STRAIN of this bacteria has evolvedBrain Pop link

Lesson learned:Only use antibiotics when necessaryMany strains are resistant to penicillin, the first antibiotic usedHumans are creating Super Strains with continued misuse of antibioticsSimilar occurrences with insects and insecticides

What causes extinction?Death rate higher than birth rateUsually due to rapid env. changesThese env. changes cause major drop in popn size if species cannot adaptVariation drops!Less variation to pass onOffspring essentially inbreeding, variation drops even moreNO VARIATION = NO ADAPTIVE VALUE = EXTINCTION