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Rates of evolutionary change and extinctions

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Rates of evolutionary change and extinctions

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Rates of evolutionary change and extinctions

  1. 1. EVOLUTION AND ADAPTATION Rate of Evolutionary Change, Endangered Species & Extinction
  2. 2. Rates of Evolutionary Change: Gradualism • Evolutionary change that occurs slowly and constantly over time • Based on evidence from fossil record where some organisms have evolved slowly (in geological time) • Modern organisms have changed very little from ancient organisms • Ex. Sharks, crocodiles, horseshoe crabs, cockroaches
  3. 3. Rates of Evolutionary Change: Punctuated Equilibrium • Long periods of stability where little change occurs followed by periods of rapid change to a species • Caused by environmental conditions such as an ice age. Some species die off, others are able to adapt quickly and survive • Animals with higher reproductive rates are better able to adapt. • Ex. Mammals, birds
  4. 4. Gradualism Punctuated equilibrium
  5. 5. Endangered Species • Species considered likely to become extinct are categorized by the International Union for Conservation of Nature (IUCN) • Red List Species are ranked according to their risk of extinction Percent of total species considered threatened by the IUCN Critically Endangered Endangered Vulnerable
  6. 6. Endangered Species & Extinction • Extinction can be natural part of evolution as species fail to adapt to a changing environment and less fit organisms do not survive. • Human caused/influenced sources of extinction: • Poaching/Hunting • Habitat destruction • Invasive species • Pollution • Climate change • What else?
  7. 7. Something to think about • Compare the graph of worldwide threatened species and the numbers of Canadian threatened species • What group is most at risk worldwide? In Canada? • Why the difference? • Hypothesize why these groups are especially threatened? • Which group is least at risk? Why?
  8. 8. What is it?
  9. 9. • http://www.onegreenplanet.org/environment/where-have-all-the-pangolins-gone/ • https://youtu.be/gz4HXyxcess
  10. 10. Extinction • Complete disappearance of a species from Earth • Background extinction – Ongoing extinctions of a few species at a time due to failure to adapt, competition, etc. • Mass extinction – Extinction caused by catastrophic event that eliminates majority of species. Meteor strike, ice age, climate change etc • Major geological eras are marked by mass extinctions • Extinctions leave open niches for other species to adapt to and fill • Extinctions increase speciation

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