Reasons for Extinction (HL IB Biology)

Anthropogenic extinction

• Extinction that has been caused by human activities is referred to as anthropogenic extinction
• Scientists believe that we are currently experiencing a mass extinction event, and that human activities are playing a large role
  • There have been five mass extinction events in the past, so the current round of extinctions could be the sixth

Anthropogenic extinction case study: North Island giant moas

• The North Island giant moa (Dinornis novaezealandiae) was a large, flightless, herbivorous bird that lived in New Zealand until the year 1300
• Humans arrived in New Zealand between 1200-1300, and it is thought that the moas were hunted to extinction by humans by 1300

Public domain, via Wikimedia Commons

The North Island giant moa (Dinornis novaezealandiae) was once thought to be several different species of moa due to size differences between larger females and smaller males, hence the image here being labelled with a different species name

Anthropogenic extinction case study: Caribbean monk seals

• Caribbean monk seals (Neomonachus tropicalis) lived in the oceans around the gulf of Mexico and the Caribbean, and were declared extinct in 2008, though it is believed that they may have gone extinct before this
• Their docile nature and their habit of lying out on the rocks meant that these seals were easy for European colonists to hunt for their oil and meat

CC BY-SA 4.0 via Wikimedia Commons

Caribbean monk seals were hunted to extinction to provide humans with oil and food

Anthropogenic extinction case study: student choice

• A third case study should be chosen and researched
• Consider the following factors
  • The species chosen should be from a local or familiar region
  • The species must have gone extinct due to human activities
  • The case studies above give an indication of the level of detail required
• Examples of extinct species from different parts of the world include:
  • Baiji (Lipotes vexillifer), a species of river dolphin
  • Passenger pigeon (Ectopistes migratorius)
  • Paradise parrot (Psephotellus pulcherimus)
  • Golden toad (Incilius periglenes)
  • St Helena darter (Sympetrum dilatatum), a species of dragonfly