7.11 Extinction

• Extinctions have occurred throughout Earth's history
• Extinction


  The disappearance of a species such that no future generations are going to naturally populate the earth
• Extinctions naturally occur and are part of a history of life on Earth
• Extinction rates can be rapid during times of ecological stress
• Extinctions can occur on a large scale and wipe out large numbers of species at one time
• Extinctions can be caused by catastrophic changes to an ecosystem, such as solar flares, rising sea levels, volcanic eruptions, or an asteroid impacts
• Human activity can drive changes in ecosystems that cause extinctions
• Human activities that can drive extinctions

  • Habitat loss
  • Climate change
  • Habitat degradation
  • Pollution
  • Poaching
  • Invasive species
• Speciation


  The process by which populations of organisms become reproductively isolated and new species form
• High species biodiversity can result from high level speciation and low levels of extinction
• Low species biodiversity can result from low levels of speciation and high levels of extinction
• The Earth is able to recover from large scale extinction events
• Niche


  The role an organism plays within its environment
• When a species goes extinct, it leaves an open niche for another species to occupy
• Extinction can lead to rapid speciation rates and adaptive radiation
• After dinosaurs went extinct, the ancestral mammal group occupied the open niche and experienced adaptive radiation