Species-Area Relationships

Question 1

What are the processes affecting regional and local diversity?

Answer 1

Local:
- Competitive exclusion
- Chance extinction
- Predatory exclusion
- Ecological interactions

Regional:
- Immigration
- Speciation
- Mass extinction

Species interactions are not sufficient enough to limit local richness and saturate communities. Communities are open to regional influences.

Question 2

What the general rules regarding larger areas and SARs?

Answer 2

Larger areas:
- More species
- More habitats
- More individuals

Question 3

What is the general SAR equation for islands?

Answer 3

log (S) = log c + z logA where,
S = number of species
A = area
Z = constant measuring of slope of S vs A
c = constant measuring number of species on a given area

Question 4

What is the significance of the Z value?

Answer 4

Represents how the area affects number of species found.

The larger the value of Z, the more species added to a given amount of area.

Also, the larger the value of Z, the more species lost for a given amount of habitat area destroyed.

Question 5

What are the 3 scales SARs operate at?

Answer 5

Sample-area - Larger area within a biogeographic province tends to include more habitats and more species.
Archipelagic - Larger islands have larger populations and lower extinction rates.
Interprovincial - Larger provinces have higher speciation rates and lower extinction rates, leading to diversity in proportion to area.

Question 6

What can SARs be used to predict?

Answer 6

How habitat loss may alter community diversity.

Question 7

What is the problem with using SAR models?

Answer 7

Ignores species identity, habitat heterogeneity, population sizes and viability of small populations.