Species-area relationships

Question 1

Biodiversity hotspots are more susceptible to climate change. True or false?

Answer 1

True.

Question 2

When there is little overlap of biodiversity hotspots species are easier to conserve. True or false?

Answer 2

False: when there is little overlap it makes conservation very difficult.

Question 3

Where is global species richness distributed?

Answer 3

Greatest diversity is found in the southern hemisphere, in South America, African and parts of Asia like India.

Question 4

Where are the most threatened areas of species richness?

Answer 4

In the areas with greatest diversity: in the southern hemisphere in South America, African and parts of Asia like India.

Question 5

Where are the highest areas of endemic species richness?

Answer 5

Again largely in the southern hemisphere, with the highest levels of endemism off the Pacific coast of South America, around Ecuador and the Galapagos.

Question 6

Where is global species richness distributed?

Answer 6

Greatest diversity is found in the southern hemisphere, in South America, African and parts of Asia like India.

Question 7

Does the global distribution of hotspots follow the pattern of species richness?

Answer 7

Yes: they are found in the southern hemisphere, in South America, African and parts of Asia.

Question 8

What is the theory of island biogeography?

Answer 8

One that seeks to explain the species richness in the colonisation islands.

Question 9

In the theory of island biogeography what 2 factors are considered?

Answer 9

1. Colonisation (or immigration)

2. Extinction

Question 10

In the theory of island biogeography what does colonisation depend on?

Answer 10

The area of the island plus its level of isolation.

Question 11

In the theory of island biogeography what does extinction depend on?

Answer 11

The area of the island.

Question 12

The following equation enables us to work out species richness:

S = S0A(z)

Explain the terms.

Answer 12

S = species richness
S0 = intrinsic species diversity
A = area
z = rate at which species richness increases with area, or 'spatial species turnover'

Question 13

S = S0A(z) is a power function. Why do we take the log of both sides?

Answer 13

For ease of use.

Question 14

If you expand out S = S0A(z) as a logarithmic function, what are you left with?

Answer 14

log(S) = (logS0) + z(logA)

This is equivalent to y = mx + c, enabling us to draw species richness on a graph.

Question 15

What is the general trend observed on species richness vs. area graphs?

Answer 15

The number of species increases with area.

Question 16

If you expand out S = S0A(z) as a logarithmic function, what are you left with?

Answer 16

log(S) = (logS0) + z(logA)

This is equivalent to y = mx + c, enabling us to draw species richness on a graph.

Question 17

On a species-area richness graph, outliers from the general trend indicate what?

Answer 17

Diversity cold or hotspots

Question 18

Changes to the gradient on a species richness-area graph may indicate what?

Answer 18

Disturbances to the habitat like fragmentation or destruction.

Question 19

In the species richness equation of S = S0A(z), why is ‘z’ the parameter of most interest?

Answer 19

Because it describes the rate at which we are discovering new species, important for conservation etc.

Question 20

In the species richness equation of S = S0A(z), why is ‘z’ the parameter of most interest?

Answer 20

Because it describes the rate at which we are discovering new species, important for conservation etc.

Question 21

What factors can affect ‘z’? Give 2.

Answer 21

1. Habitat diversity: more diverse habitats should in theory have more species
2. Area: is it just an inherent quality of increasing area that there are more species present?

Question 22

‘z’ increases with area because of which 2 factors?

Answer 22

1. Size: if an area is larger it can accommodate more species, probability dictates it more likely to be species rich.
2. Habitat heterogeneity: if the habitat is heterogeneous then there are multiple niches that can be occupied by different organisms.

Question 23

What assumption is made in passive sampling? What prediction does passive sampling make of species richness?

Answer 23

That individuals are randomly scattered across a landscape: this is obviously not true.
Passive sampling predicts an increase in species richness with area.

Question 24

In a study by Ricklefs and Lovette in 1999 on fauna of the Caribbean, what was found to effect the species diversity of:

a) butterflies
b) herps (reptiles)
c) birds
d) bats

Answer 24

a) Habitat diversity
b) Habitat diversity
c) Habitat diversity and area
d) Area

Question 25

Why is it that using z in conservation models often leads to overestimates of loss (of diversity)?

Answer 25

SARs (species-area relationships) are too simple: they do not take into account population dynamics like species interaction, adaptation, imm/emigration etc.

Question 26

Global extinctions are pretty evident. Why are local extinctions hard to predict/define?

Answer 26

They may be due to temporary migration patterns.

Question 27

Define extinction debt.

Answer 27

The future extinction of a species based on past events: there is a time lag between the event that causes extinction, e.g. habitat loss, and the actual extinction of all members of that species. Basically doomed species linger...

Question 28

Species-area curves are useful tools but they are vague. They depend on scale, endemism and the physical attributes of each species. They should be used with caution in estimating future diversity. True or false?

Answer 28

True.

Question 29

Define endemism.

Answer 29

The ecological state of a species being unique to a defined geographical region.

Question 30

As sampling area increases what do we assume about the state of species being added?

Answer 30

They are rarer, with common species being found in smaller areas.

Question 31

Finding rarer species increase our 'z' value. True or false?

Answer 31

True.

Question 32

What is a cosmopolitan species?

Answer 32

Generalists or good dispersers. Cosmopolitan species are found every where.

Question 33

What effect do cosmopolitan species have on 'z' values?

Answer 33

They decrease them, as sampling a larger area doesn't reveal rare species, only more of the same cosmo ones.

Question 34

On a species richness-area graph with species richness of the y-axis and area on the x-axis, what does the y-intercept represent?

Answer 34

An estimate of local diversity for the particular area.

Question 35

What effect does endemism have on z values?

Answer 35

It increases z.

Question 36

Smaller organisms often have higher rates of dispersal. True or false?

Answer 36

True: smaller species are often cosmopolitan species.

Question 37

What do SARs depend on?

Answer 37

The discovery of the first individual of each species.

Question 38

What does extinction depend on?

Answer 38

The disappearance of the last individual of each species.

Question 39

What is an EAR?

Answer 39

The endemic area relationship.

Question 40

zEAR = zSAR when individuals are randomly scattered | across the landscape. Is this observed in nature?

Answer 40

Not often, species are usually clustered in space.

Question 41

What 2 factors must be considered in zEARs?

Answer 41

1. Number of individuals of each species | 2. Spatial structure of each species

Question 42

Define a) alpha and b) beta species diversity.

Answer 42

a) Alpha diversity: the mean species diversity of a habitat at a local scale b) The differentiation in diversity among habitats

Question 43

Whittaker in 1972 came up with the concept of a) alpha and b) beta species diversity. Define them both.

Answer 43

a) Alpha diversity: the mean species diversity of a habitat at a local scale b) The differentiation in diversity among habitats

Question 44

Species-area curves are useful tools but they are vague. They depend on scale, endemism and the physical attributes of each species. They should be used with caution in estimating future diversity. True or false?

Answer 44

True: SARs are too simple to be used effectively in conservation.