Mass Extinctions Through Deep Time

__% of species that have ever existed are extinct - mostly from _____ causes, only _% from mass extinctions.

99; evolutionary; 5

“_____ is the rule, _____ is the exception.” - Carl Sagan

Extinction; survival

Define extinction.

When the last member of a species/clade dies out.

Define mass extinction.

Any substantial change in the rate of extinction suffered by more than 1 geographically widespread higher taxon during a relatively short interval of geological time, resulting in an at least temporary decline in their standing diversity

What is the recipe for mass extinction?

• Take lots of change

• Add a pinch of time

• spread the damage globally & to lots of clades

What is the result of a mass extinction event?

• Reduced diversity of life

• Fewer ecological niches occupied

• Disruption of major nutrient cycles

How are mass extinctions recognized?

By looking at when species disappeared on an evolutionary tree (& patterns of the species who disappeared), looking at deep-time records of diversity

The “Big _” refers to the major mass extinction events in Earth’s history

5

What is the name of the mass extinction event we are experiencing right now?

Holocene (Anthropocene)

__% of terrestrial species are predicted to be extinct by 2100.

27

What is the lilliput effect? Why does this occur?

After an extinction event, species get smaller; heat stress, lower oxygenation, & acidification

What is biotic recovery: lazarus taxa?

Reappearance of clades that disappeared before/during the event 

What is biotic recovery: Elvis taxa?

Appearance of species that very closely resemble extinct forms 

What are the 3 main agents of destruction?

• Astronomical (extraterrestrial causes)

• Geological (terrestrial causes)

• Biological

What are the Earthbound mechanisms of destruction?

• Global temperature decline

• Marine regression

• Volcanism

• Oceanographic changes