Extinction and global change

Question 1

What is background extinction?

Answer 1

The continual, normal process of species going extinct over time, causing turnover in Earth’s species

Question 2

What is a mass extinction?

Answer 2

A relatively sudden increase in extinction rates that kills many species, opening niches for other lineages to diversify

Question 3

What caused the Cretaceous-Tertiary extinction (~65 mya)?

Answer 3

A large asteroid impact, resulting in extinction of 71-81% of species, including non-avian dinosaurs

Question 4

What caused the End Triassic extinction (~200 mya)?

Answer 4

Falling sea levels, with extinction rates of 76-84% of species

Question 5

What caused the Permian-Triassic extinction (~250 mya)?

Answer 5

Formation of supercontinent Pangea causing hot, dry conditions, with up to 97% species extinction

Question 6

What caused the Late Devonian extinction (~364 mya)?

Answer 6

Major environmental changes including ocean oxygen depletion, rising sea levels, and global cooling

Question 7

What caused the Ordovician-Silurian extinction (~440 mya)?

Answer 7

An intense ice age triggered by supercontinent location over the South Pole

Question 8

What is notable about the current (sixth) mass extinction?

Answer 8

It is occurring over hundreds of years, much faster than past mass extinctions that took millions of years

Question 9

What are key human-driven causes of current extinction?

Answer 9

Climate change (rising CO2), rising global temperatures, habitat loss (deforestation, agriculture), and increased frequency of extreme events

Question 10

How does climate change impact extinction risk?

Answer 10

Rising CO2 leads to global temperature increases, decreasing sea ice, and more frequent extreme weather, stressing species

Question 11

What role does habitat loss play in extinction?

Answer 11

Conversion of forests to pasture and cropland has drastically reduced habitats for wild mammals, with 96% of mammals now livestock

Question 12

Why might rapid environmental change cause evolutionary mismatches?

Answer 12

If environmental changes happen faster than natural selection and adaptation, species may be poorly adapted, reducing fitness

Question 13

How can behavioural flexibility help species survive rapid environmental change?

Answer 13

Different populations with flexible behaviours can better cope with changing conditions, increasing survival chances