PCE - 9

Question 1

what is the definition of a community?

Answer 1

consists of all the individuals of all

the species that inhabit a particular area

Question 2

what measures the number of species within a community?

Answer 2

the species richness

Question 3

what is a (alpha) diversity?

Answer 3

species richness within sites

Question 4

what is y diversity?

Answer 4

species richness in all sites - both focal and surrounding

Question 5

what is B diversity (jaccard coefficient)?

Answer 5

measures how different the samples are across the sites or the turnover of species - to compare the community composition of 2 sites

Question 6

what is the eqaution for the jaccard coefficient?

Answer 6

a/a+b+c
a = number of species found in both sites
b = number of species found in site 1 but not 2
c = number of species found in site 2 but not 1

Question 7

what does it mean if a site is nested?

Answer 7

we can predict the identities of species absent in smaller sites - because all the sites have the same species within but the smaller sites just have less

Question 8

what can you determine from species area relationships?

Answer 8

• How many different species co-occur in a
  defined area?
• How does species richness vary with area?

Question 9

are SARs linear relationships between areas of islands and the number of species on them?

Answer 9

no they are non linear

Question 10

what is the initial equation for SARs?

Answer 10

S = cA^z
S = number of species 
A = area 
c = intercept 
z = exponent

Question 11

what is the log equation for SARs?

Answer 11

log10 (S) = log10 (c) + zlog10 (A)

Question 12

what sections of the log equation do the y intercept and gradient of the line replace?

Answer 12

log10 (S) = log10 (c) + zlog10 (A)

log10 (S) = Y - INTERCEPT + GRADIENT log10 (A)

Question 13

what are habitat patches?

Answer 13

small isolated areas of land - like islands

Question 14

describe the ‘Biological Dynamics of Forest Fragmentation’ experiment in Brazilian rainforest running since 1980’s

Answer 14

• Mimics fragmentation common in heavily logged forest

Question 15

what causes the intercept C to vary?

Answer 15

varies greatly depending on the taxa and region

Question 16

does the slope z vary?

Answer 16

varies but is often close to 0.26 in true island systems

Question 17

How is it possible to predict not only how many species are likely to be lost from environmental change, but also which species?

Answer 17

depends on nestedness

• Larger sites harbour common and rare species
• Smaller sites harbour only common species

Question 18

what does the SAR of mainland provide?

Answer 18

Mainland SAR provides an approximate predictor of maximum diversity on islands

Question 19

describe saturation by isolation?

Answer 19

• More distant islands are less saturated than islands
  close to the mainland
• alpha diversity declines with isolation from the mainland

Question 20

in the example of boreal mammals what affect did the 3 degree increase have?

Answer 20

• 3 degree increase in temperature
• Altitudinal shift in habitat type
• Pinion-juniper woodland restricted to mountain tops
• Reduction in habitat area
• new habitat became ‘island’ species couldn’t survive outside of that habitat
• no dispersal across montane valleys to colonise new
  sites
  – distribution and abundance decline in proportion to
  habitat loss

Question 21

whats the difference between mainland and island SARs?

Answer 21

“Mainland” has a shallower slope - Mainland SAR provides an approximate predictor of maximum diversity on islands