Species Diversity And Ecological Stability

Question 1

Where is species diversity often low?

Answer 1

In extreme environments dominated by abiotic factors and where populations fluctuate dramatically

Question 2

What creates a cycle of population rise and fall?

Answer 2

In an area with few food species a change in availability of one food species will have a big impact on the number of predators

Question 3

What areas will have a higher biodiversity?

Answer 3

Less abiotically extreme environments
Where populations are dominated by biotic factors

Question 4

What are some areas that are dominated by biotic factors?

Answer 4

Tropical rainforests
Coral reefs

Question 5

What is a common way diversity can be quantified?

Answer 5

The Simpsons diversity index

Question 6

What is the formula for the simpsons diversity index?

Answer 6

D= N(N-1)
———-
Sum of n (n-1)

Question 7

What is N on the simpsons diversity index?

Answer 7

Total number of all organisms (all species)

Question 8

What is ‘n’ on the the simpsons diversity index?

Answer 8

Total number of organisms of an individual species

Question 9

How is diversity calculated from the Simpson diversity index?

Answer 9

The higher the value of D the higher the biodiversity

Question 10

What can be used to predict how many species are in a habitat?

Answer 10

Past rate of discovery can be used as the basis for estimating the number
The gradual reduction of finding new species can be sued to estimate how many individuals have not been found

Question 11

How many new species are found every year?

Answer 11

20,000 a year

Question 12

What are the estimates for the total number of species?

Answer 12

5 to 100 million

Question 13

How many species have been named so far?

Answer 13

2 million

Question 14

What areas of habitats are currently inaccessible?

Answer 14

Tree canopy of tropical rainforest
Deep sea-floor
So not fully researched

Question 15

What are population dynamics?

Answer 15

The processes that can cause populations to change in size and structure

Question 16

What controls the number of species that live in an area?

Answer 16

The balance of factors that either increase or reduce the population

Question 17

What will cause a population to increase?

Answer 17

Reproduction rate is high and death rate is low

Question 18

What will cause a population to decline?

Answer 18

Reproduction rate is low and death rate is high

Question 19

What is the maximum birth rate determined by?

Answer 19

The natural ability of the species to reproduce

Question 20

How has evolution affected birth rates? I

Answer 20

Evolution has procured birth rates that are appropriate for the death rate

Question 21

What will the birth rate be for a species with a lower chance of survival?

Answer 21

Higher birth rate

Question 22

What is death rate controlled by?

Answer 22

Environmental factors such as disease, drought, predation and shortage of food

Question 23

What are r-selected species?

Answer 23

Theses are species that can respond rapidly to low survival rates
They reach sexual maturity quickly and produce many young and can disperse widely

Question 24

What are some examples of r-selected species?

Answer 24

Locust
Spiders
Rowan (plant)
Rabbit

Question 25

What are k-selected species?

Answer 25

Theses are species that recover slowly from population decline
Reach sexual maturity at an older age
Produce few young
Often live for a long time

Question 26

What would happen if the death rate of k-selected species increased due to habitat change or human exploitation?

Answer 26

May cause a population crash as the slow reproduction rate means the losses couldn’t be replaced

Question 27

What are some examples of k-selected species/

Answer 27

Whales
Elephants
Rhinos

Question 28

What is the maximum sustainable yield?

Answer 28

An estimate of the greatest population that is possible without causing unsustainable long-term population decline

Question 29

What variables are needed to forecast a change in population size?

Answer 29

Current population
Number of births and deaths
Number of individuals immigrating or emigrating

Question 30

How do you work out population?

Answer 30

Population= starting population+ births+ immigrants- deaths- emigrants

Question 31

What are density independent factors?

Answer 31

Factors where the population density has no effect on the chances of survival of an individual

Question 32

What are some examples of density independent factors?

Answer 32

Drought
Flood
volcanic eruption

Question 33

What are density dependant factors?

Answer 33

Factors where the chances of an individual surviving depend on the population density of the species

Question 34

when is population density a bad thing?

Answer 34

if individuals are closely related and are all vulnerable to disease then rapid spread due to close proximity could cause extinction

Question 35

How does food supply affect mortality rates? (population density)

Answer 35

Intra-species competition for food is greatest when the population density is high

Question 36

How does disease affect mortality rates?

Answer 36

Diseases spread more easily between individuals when they are close together

Question 37

What happens to the dependant factors as density increases? (Animal survival)

Answer 37

The dependant factors become more important until the combined mortality rate caused by density dependant factors plus density independent factor cause population to reduce

Question 38

What is carrying capacity?

Answer 38

The greatest that an area can support indefinitely without damaging or over exploiting the environment

Question 39

How are mortality rate and carrying capacity linked?

Answer 39

The mortality rate changes if population size is above or below the carrying the capacity so the population size. Changes back to the carrying capacity

Question 40

What happens when prey population rises?

Answer 40

There is a lot of food for the predators so their population increases

Question 41

What happens when the predators population rises?

Answer 41

Causes prey population to decline creating a food shortage so the predator population declines allowing the prey population to rise again

Question 42

Why might artificial population control be needed?

Answer 42

To enable species or habitats to survive where the natural control mechanism no longer controls population

Question 43

What is a method of artificial population control?

Answer 43

Culling

Question 44

How might the artificial population control help an endangered species with a low breeding rate?

Answer 44

A captive breeding and release programme to maintain or increase the population

Question 45

How can a non-indigenous species can act as artificial population control?

Answer 45

A non-indigenous species may reduce populations of indigenous species because it is a predator, competitor or pathogen

Question 46

How can removing an indigenous predator lead to artificial population control?

Answer 46

As its prey species becomes overpopulated and needs to be culled to avoid ecological damage it may cause to other species

Question 47

What is an example of how removing the indigenous predator lead to artificial population control?

Answer 47

Wolves were exterminated in Scotland now their prey the red deer has to be culled to prevent over-grazing