Anthropocene and Mass Extinction

What is extinction?

The last individual or group of a species dies, meaning no representatives of that lineage remain on Earth

At what taxonomic level can extinction occur?

Any taxonomic level

What is a mass extinction?

Occurs when a large proportion of species go extinct within a relatively short period of time

How does extinction relate to the replacement of species?

They disappear much faster than they are replaced by new species

What are some causes of historical mass extinctions?

1. meteor strikes

2. volcanic activity

3. continental movement

4. temperature changes

5. changes in CO₂

6. sea-level changes

How can meteor strikes cause mass extinctions

A major meteor impact can cause large-scale environmental changes that make conditions unsuitable for many organisms

How can volcanic activity contribute to extinction?

Volcanic activity can dramatically alter the environment, including atmospheric composition and temperature, contributing to extinction.

How can continental movement affect biodiversity?

Movement of continents changes the physical environment and habitats, potentially causing species to decline or disappear

How can temperature changes cause extinction?

Major changes in temperature can make existing environments less suitable for organisms, causing populations to decline and potentially go extinct.

How can changes in atmospheric CO₂ contribute to extinction?

Changes in atmospheric CO₂ can contribute to major environmental and climate changes, affecting organisms and ecosystems.

How can sea-level changes contribute to extinction?

Changes in sea level can alter or eliminate habitats, affecting species that depend on particular environments.

What is the background rate of extinction?

The normal average extinction rate occurring over long periods of geological time.

How is the background extinction rate measured?

It can be calculated as the number of extinctions per million species per year.

Why is it difficult to understand extinction rates precisely?

Scientists do not know the total number of species on Earth, making it difficult to determine exact extinction rates.

How does the current extinction rate compare with the background extinction rate?

The current extinction rate is many times higher than the background extinction rate.

What is the Anthropocene?

A new geological epoch characterized by the large-scale influence of humans on Earth.

How long have humans been ecologically dominant according to the notes?

Humans have been an ecologically dominant species on Earth for thousands of years.

What evidence in Earth's strata was considered for the Anthropocene?

Evidence includes atomic bomb testing, which left identifiable signals in geological strata.

What is currently the biggest cause of biodiversity loss?

Habitat loss

What happens when habitat area is reduced?

The amount of space available for species to live decreases, which can make it harder for populations to survive.

How does habitat loss affect resource availability?

Habitat loss can reduce the availability of resources needed by organisms.

What are some examples of changes that can alter habitats?

Ocean acidification and changes in habitat structure.

How can habitat fragmentation affect species?

Fragmentation can separate populations into smaller groups and may result in less genetic diversity.

Why can human activity contribute to extinction?

Human activities can alter habitats and environmental conditions, contributing to population declines and increased extinction rates.