EE Lecture 35: Drivers of biodiversity decline

Question 1

outline the main aspects of drivers of biodiversity decline

Answer 1

habitat loss
overexploitation
introduced species
chains of extinction

Question 2

give an example of an extinction where multiple factors contributed to the extinction
when did it go extinct
why did it go extinct

Answer 2

on the island of Raiatea -v. restricted range to start with
Partula turgida (snail)
died out 01/01/96
went extinct due to Euglandina rosea - the native snail popn which predated on them
then the final straw was a microsporidian disease

Question 3

what does decline in popn normally resulkt from

Answer 3

an interaction between driver and species’ biology

Question 4

discuss overexploitation in prehistory

Answer 4

megafaunal extinction

Question 5

why do large species tend to be the most vulnerable

Answer 5

theyre slower to recover
more appealing for hunting
possible danger to human
slower reproductive rates

Question 6

give an example of a very large mammal that was once v abundant but now extinct

Answer 6

American buffalo

Question 7

discuss overexploitation in human history

Answer 7

on islands, timings of extinction fits human colonisation
MADAGASCAR:1000AD
-giant aye aye and sloth lemur
AUSTRALIA:5000BC
-giant marsupial ground sloth
NZ:1350AD
-giant moa

Question 8

when did humans colonise madagascar, which species did this cause decline of

Answer 8

1000AD

extinction of giant aye-aye and sloth lemur

Question 9

when did humans colonise australia

which species did this cause decline of

Answer 9

5000BC

giant marsupial ground sloth

Question 10

when did humans colonize NZ

which species did this cause decline of

Answer 10

1350AD

giant moa

Question 11

how is overexploitation happening at present

Answer 11

rising demand for animals

the theory of maximum sustainable yield

Question 12

what is the MSY

Answer 12

the theory of maximum sustainable yield

Question 13

what is the logistic model of a popn growing towards its carrying capacit

Answer 13

dN/dT = rN(1-N/K)

K -caryring capacity
r-intrinsic rate of increase

Question 14

what curve should the logistic model of a popn growing towards its capacity look like

Answer 14

a sigmoidal curve
time on x
N on y

Question 15

at what carrying capacity is the max rate of popn grown

Answer 15

when N=K/2 which = rK/4 individuals per year

Question 16

what two rates need to be thought about when working out MSY

Answer 16

harvesting rate

recruitment rate

Question 17

what is habitat loss aka wrt declining biodiv

Answer 17

fragmentation

Question 18

what has habitat loss been driven by

Answer 18

the expansion of the human pop and its economy

Question 19

what does dispersal between habitat fragments require

Answer 19

corridors

Question 20

whayt did gareth hardin propose

Answer 20

the tragedy of the commons

Question 21

what was the tragedy of the commons

Answer 21

suggests why we use biodiversity unsustainably

Question 22

what effect can habitat loss have on species

Answer 22

edge effects

Question 23

What are edge effects

Answer 23

changes in population that occur at the boundary of two habitats.
Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range.

Question 24

why are introduced species drivers of biodiversity decline

Answer 24

outcompete
predate
knock on effect

Question 25

give an example of a knock on effect leading to biodiv decline due to introduced species

Answer 25

foxes kill birds, droppings dont fertilise ground, vegetation changes

Question 26

what are chains of extinction

Answer 26

loss of one species affects another

Question 27

give an example of chained extinction

Answer 27

In Aleutian Islands, sea lions gone, so killer whales eat all the sea otters os the kelp forest disappears

Question 28

what is the millenium ecosystem assessment

Answer 28

gives a status on the main threats over the last century

Question 29

give an example of introduced species leading to extinction

Answer 29

Harlequin vs native ladybirds

-recent invasion in britain and belgium

Question 30

what are the current threats to each biome outlined by the millennium ecosystem assessment

Answer 30

habitat change
climate change
invasive species
overexploitation
pollution

Question 31

what were the first threats to make a difference to biodiversity decline

Answer 31

overexploitation and introduced species