Chapter 1: Extinction

Question 1

how is our age structure skewed?

Answer 1

skewed towards a large portion of young individuals

Question 2

population momentum

Answer 2

age structure causing transient effect on population growth

Question 3

human population growth & humans meet biodiversity

Answer 3

• not all age/stage classes are created equal
• not all species are created equal

Question 4

not all age/stage classes are created equal

Answer 4

for people, deer, or salamanders: population growth is affected by distribution across stages

Question 5

how is population growth affected across stages?

Answer 5

affected by distribution

Question 6

not all species are created equal

Answer 6

• numbers, distributions
• per capita effects

Question 7

humans have a ______ per capita effect

Answer 7

large

Question 8

5 categories of anthropogenic stressors on wildlife

Answer 8

• conversion of land & sea
• overexploitation through harvest
• invasive species (including disease)
• pollution
• climate change

Question 9

humans and extinction rates

Answer 9

• more species on earth now than ever before
• around 98% of the species that have evolved on earth over the past 3 billion years are now extinct

Question 10

extinction as a process

Answer 10

natural & inevitable

Question 11

are humans increasing extinction rates?

Answer 11

• extinction rates are higher
• contemporary humans caused extinction rate to be high enough to lead to a 6th mass extinction

Question 12

5 mass extinctions

Answer 12

• Ordovician Silurian
• Late Devonian
• Permian Triassic
• Triassic Jurassic
• Cretaceous Palogene

Question 13

mass extinction

Answer 13

a sharp spike in the rate of extinction of species caused by a catastrophic event or rapid environmental change

Question 14

life span of a species

Answer 14

• average time from speciation to extinction
• expressed as a rate (E/MSY)

Question 15

E/MSY

Answer 15

• # species extinction per million species per year
• # species extinction per 10,000 species per 100 years

Question 16

baseline species lifespan

Answer 16

2 E/MSY

Question 17

how do current rates compare to the deep time baseline?

Answer 17

• 10-30x higher during the past century
• likely already undergoing 6th mass extinction