3: Intro to macroecology

Question 1

Define macroecology

Answer 1

Use compilations of data (on single communities or assemblages) to study large scale ecological patterns in space/time

Question 2

Define range size

Answer 2

= geographic distribution of a species
- Patchy
- Scale dependent → characteristics will vary depending on which scale you are looking at (e.g local vs global)

Question 3

What are the 2 ways we measure range size?

Answer 3

Extent of occurrence (EoO)
Area of occupancy (AoO)

Question 4

Define Extent of occurrence (EoO)

Answer 4

Area within range boundary
Includes gaps
Scale independent

Question 5

Define Area of occupancy (AoO)

Answer 5

Area of occupied locations within boundary
Excludes gaps
Scale dependent

Question 6

Range size is a good indicator of ______ ____

Answer 6

Extinction risk

Small range species = higher risk of extinction

Question 7

Describe Rapoport’s rule

Answer 7

→ Species have smaller latitudinal ranges at low latitudes (e.g temperate and polar regions)
→ links to LDG (tropical species have smaller ranges, can pack more species into tropics, so tropics have higher richness)

Question 8

What are the 3 possible mechanisms for Rapoport’s rule?

Answer 8

1. Climatic tolerance
2. Hisorical factors
3. Evolutionary age/ taxon cycles

Question 9

Describe how climatic tolerance may be a mechanism for Rapoport’s rule

Answer 9

• Seasonal variation greatest at high latitudes
• Species at high lats cope with wider temp ranges
• High lat species physiologically capable of occuring in wide range of environs so have large ranges

Question 10

Describe how historical factors may be a mechanism for Rapoport’s rule

Answer 10

• High latitudes have lots of glaciation/ ice age events
• These cause species extinctions and species with small geographic ranges more vulnerable to extinction
• More small ranged species go extinct at high lats so range size tends to be larger

Question 11

Describe how evolutionary age/taxon cycles may be a mechanism for Rapoport’s rule

Answer 11

• Tropics cradles of speciation
• Tropics museums of old species
  = So tropics tend to have species with small ranges

Question 12

Describe the Climatic variability hypothesis

Answer 12

Taxa from environmentally variable habitats evolve wider tolerances
= establish wider distributions along climate gradients than taxa originating from relatively stable habitats

• No clear LDG in temp seasonality
• But… plenty of spatial variation

Question 13

Does Rapoport’s rule generalise globally?

Answer 13

No, Gaston et al (1989) found it is primarily in the Palearctic and Nearctic

BUT, the key mechanism proposed to explain it (climatic variability) does generalise

Question 14

Pop. with large range size = speciation ____ likely, due to…

Answer 14

Speciation is less likely as geographic barriers are more likely to be ineffective

Question 15

Pop. with smaller range size = extinction ____ likely, due to…

Answer 15

Extinction is more likely as low speciation probability

Question 16

Describe the connection between SAR and LDG patterns

Answer 16

SARs should be steeper at lower latitudes and decline as the average species range size increases towards the poles