The biodiversity crisis

Question 1

___ species have gone extinct since 1600

a) 500
b) 1,000
c) 2,000
d) 35,000

Answer 1

b)

Question 2

is the background rate for species extinction more or less than the trend?

Answer 2

It is less (trend = 2.7 spp/year, BG rate = 1 app/year)

Question 3

Explain the 50 years rule.

Answer 3

We have to wait 50 years before declaring a species extinct.

Question 4

Place the following endangered species from bigger to smaller number of extinct since 1600.
Arthropods, Vertebrates, Molluscs, Non-flowering, Dicots, Monocots

Answer 4

Dicots > Vertebrates > Molluscs > Monocots > Arthropods > Non-flowering

Question 5

Fill in the blank: evidence about rates from well known taxa:
There are 5000 species of mammals on earth, there have been __ extinctions in the last 400 years. Background rate is expected to be __, but it is much __ (higher/lower) than that. 169 species are ___ endangered. Much __ (higher/lower) rates of extinctions for well known taxa.

Answer 5

89, 2, higher (45x), critically, higher

Question 6

Discuss the Centinelan Extinctions

Answer 6

Al Gentry visited Centilena Ridge in Ecuador in 1978. He saw 90 endemic species that were not known to science. Forest cover in Ecuador is decreasing dramatically. 1978-86 cleared for agriculture. 1992: only 17 species were found = 73 extinct! E. O. Wuson coined the tern “Centinelan Extinctions”: The unknown and undescrived species that go extinct without us knowing.

Question 7

Predictions from species-area curves: Fill in the blank:

a) ____ ____ is the #1 threat to biodiversity
b) __% of pre-1970 forest cover remains in 2021
c) Rate of ___: 0.3% per year in Africa and South America (forest to land use)
d) Only __ of the forest will remain in 2140.
e) Much ___ in Asia: 33-94% already lost (Zimbabwe-Philippines)

Answer 7

a) habitat loss
b) 80.1%
c) deforestation
d) half
e) worse

Question 8

Who am I?

The future extinction of species due to events in the past – typically habitat loss

Answer 8

Extinction debt

Question 9

Assumptions: The biodiversity crisis

a) 10 million species on earth: half are in __ __.
b) Log S = ?
c) S when habitat is reduced to 50%: Log S = ?
d) S is __ to area to the a
e) If slope of the species area curve = 0.25. S = x, y% of species are extinct. z species per year or more
f) __ __: half species on earth go extinct
g) The rate at which we are losing species per year can be described as __ __.
h) __ years to accomplish this at 6000/year
i) Are 6000 species/year really going extinct?
j) Explain the extinction debt (Brooks 1999)

Answer 9

a) tropical forests
b) a*Log area + b
c) S = B * Area to the a
d) proportional
e) x: 0.5 to the 0.25, y: 16%, z: 6000
f) Mass extinction
g) Mass extinction
h) 800
i) Probably not, but we don’t know. Haven’t named 10 million species (only 1-2 million)
j) We are losing the habitat to support 6000 species per year. Pay back this debt over the next 150 years. So yes we lose species by destroying half a forest, but we also lose the habitat to support other species.