12. The Biodiversity Crisis

Question 1

How many species have gone extinct since 1600?

Answer 1

only 1000, but this doesn’t accurately represent the crisis since there are a lot of depleting species

Question 2

What is the trend of extinction?

Answer 2

it is going up (samples can be biased but nevertheless)

Question 3

What is the 50-year-rule?

Answer 3

typically you have to wait 50 years before declaring a species extinct (and search for it)

Question 4

What are the implications of the 50-year rule?

Answer 4

a lot of species could be extinct without being declared since we have to wait to do so - the number of endangered species is a lot bigger than the number of extinct species

Question 5

Why do we have more extinction rates about well-known taxa?

Answer 5

it’s harder and less interesting to discover other groups going extinct

much higher rates when we know the taxa well

Question 6

What are centinelan extinctions?

Answer 6

unknown and unescribed species that go extinct without us knowing (they’re either hard to find, unidentified, etc.)

Question 7

What is the number one threat for extinction?

Answer 7

habitat loss - there is a very high rate of deforestation, and other habitat loss globally

Question 8

At the current rate, how long until we reach a mass extinction?

Answer 8

mass extinction: half of the species on earth go extinct

currently losing the habitat to support 6000 species a year

800 years to reach a mass extinction (with the loss of 6000 species a year)

Question 9

What is extinction debt?

Answer 9

while we’re losing the habitat for 6000 species a year, they’re not all going extinct yet so we have a lot on the brink of extinction

this debt will be ‘paid back’ over the next 150 years

Question 10

How many endangered species are there?

Answer 10

25 000, and many more endangered populations