Definition

Extinction Events are rapid and widespread decreases in the biodiversity on Earth, where a significant percentage of species die out in a relatively short geological period.

Types of Extinction Events

  • Background Extinction: Natural, ongoing process where species gradually disappear.
  • Mass Extinction: Catastrophic events causing the loss of a large number of species in a short time.

The “Big Five” Mass Extinction Events

Event Name Approximate Time (Million Years Ago) Main Cause(s) % Species Lost
Ordovician-Silurian 443 Glaciation, sea level fall ~85%
Late Devonian 372 Ocean anoxia, climate change ~75%
Permian-Triassic (“Great Dying”) 252 Volcanism, methane release ~96%
Triassic-Jurassic 201 Volcanism, climate change ~80%
Cretaceous-Paleogene (K-Pg) 66 Asteroid impact ~76%

Diagram: Timeline of Mass Extinctions

Extinction Timeline

Causes of Extinction Events

  • Asteroid Impacts: E.g., Chicxulub impact leading to the K-Pg extinction.
  • Volcanic Activity: Massive eruptions releasing gases and ash, causing climate shifts.
  • Climate Change: Rapid temperature changes, ocean acidification, and anoxia.
  • Sea Level Fluctuations: Affecting habitats and oxygen availability.
  • Methane Release: From oceanic deposits, leading to greenhouse effects.

Effects on Life

  • Loss of biodiversity.
  • Disruption of food chains.
  • Evolutionary bottlenecks and new species radiations.
  • Ecosystem collapse and recovery over millions of years.

Surprising Facts

  1. The Permian-Triassic extinction wiped out over 96% of marine species, making it the most severe extinction event known.
  2. Fungi flourished after the K-Pg extinction, as decaying matter increased due to the mass death of plants and animals.
  3. Some species, like crocodilians and sharks, survived multiple mass extinctions due to their adaptable physiology and habitats.

Case Studies

1. Permian-Triassic (“The Great Dying”)

  • Cause: Siberian Traps volcanic eruptions released CO₂ and methane, causing global warming and ocean acidification.
  • Effect: Nearly all marine life and most terrestrial species vanished.
  • Recovery: Took over 10 million years for ecosystems to stabilize.

2. Cretaceous-Paleogene (K-Pg) Extinction

  • Cause: Asteroid impact near present-day Yucatán Peninsula.
  • Effect: End of non-avian dinosaurs, rise of mammals.
  • Evidence: Iridium layer in geological strata, impact crater.

3. Ongoing Sixth Extinction

  • Cause: Human activities (habitat destruction, pollution, climate change).
  • Effect: Accelerated loss of species; estimated extinction rate is 100–1,000 times the natural background rate.
  • Case: Amphibian decline due to chytrid fungus and habitat loss.

Mnemonic for the Big Five Extinctions

“Old Dinosaurs Perished To Create”

  • Ordovician-Silurian
  • Devonian (Late)
  • Permian-Triassic
  • Triassic-Jurassic
  • Cretaceous-Paleogene

Future Trends

  • Anthropogenic Extinction: Human-driven extinction rates are increasing.
  • Climate Change: Ongoing shifts threaten many species.
  • Artificial Intelligence: Used to model extinction risks and discover new drugs/materials to mitigate effects (e.g., AI predicting species vulnerability).
  • Conservation Genomics: Genetic rescue and de-extinction efforts using CRISPR and AI.
  • Ecological Forecasting: AI-driven simulations inform conservation strategies.

Recent Research & News

  • AI in Extinction Prediction: A 2022 study published in Nature Communications (“Artificial intelligence predicts the risk of vertebrate extinctions”) used machine learning to assess extinction risk for thousands of species, improving conservation prioritization.
  • Drug Discovery: AI models now accelerate the identification of molecules that can help treat diseases affecting endangered species (ScienceDaily, 2023).
  • Material Science: AI-driven discovery of new materials helps create sustainable alternatives, reducing environmental impact (MIT News, 2021).

Artificial Intelligence Applications

  • Species Risk Assessment: AI analyzes large datasets to identify at-risk species.
  • Drug & Material Discovery: Accelerates finding solutions for conservation and sustainability.
  • Habitat Modeling: Predicts how environmental changes affect biodiversity.
  • Early Warning Systems: Detects patterns indicating potential extinction events.

Summary Table

Aspect Description
Definition Rapid, widespread loss of species
Main Causes Asteroids, volcanism, climate change, human activity
Notable Events Big Five (see mnemonic)
Effects Biodiversity loss, ecosystem collapse, evolutionary shifts
AI Role Predicting risks, discovering solutions
Future Trends Increased anthropogenic impact, AI-driven conservation

References

  • Mooers, A. O., et al. (2022). “Artificial intelligence predicts the risk of vertebrate extinctions.” Nature Communications. Link
  • “AI discovers new drugs to save endangered species.” ScienceDaily, 2023. Link
  • “AI speeds up material discovery for sustainability.” MIT News, 2021. Link

Review Questions

  1. What are the main causes of mass extinction events?
  2. Name the Big Five extinction events using the mnemonic.
  3. How is artificial intelligence helping in conservation biology?
  4. Describe one surprising fact about extinction events.

End of Study Notes