1. Aerial lakes photo

2. The Regional View All habitat is patchy
Species colonize patches by dispersal
All species go extinct

3. The Local View Communities are made up of populations
Population persistence depends on the physical and biological environment

4. What are the roles of local and regional processes in structuring communities?

5. Zooplankton photograph

6. The importance of scale
What are the roles of local and regional processes in zooplankton communities?
Observational test
global patterns of local and regional richness
Experimental tests
measuring community invasibility
measuring dispersal rates
The importance of scale
modeling spread of invaders

7. Regional vs. local control of local diversity
Regional processes
colonization
local extinction
Local processes
abiotic constraints
species interactions
if colonization  extinction
if colonization >> extinction
Regional richness
Regional richness
Local richness

8. “In a clear majority of studies, possibly the great majority, the main driver of local species richness appears to be the size of the regional species pool… Strong dependence of local richness on regional richness may arise because species interactions- the stuff of traditional community ecology- are weak” or…
J.H. Lawton (1999). Are there general laws in ecology? Oikos 84:

9. 2,832 lakes Shurin et al. 2000. Ecology 81: 3062 17 11,12 17 20 4,1423 19
1,3,5-10,
15,16,18,
22,24,25 21 13
2,832 lakes
Shurin et al Ecology 81: 3062

10. Local vs. residual regional richness
-20
-10 10 20 30 1 2 3 4 5 6 7 8
A- Cladocerans -5 15
B- Cyclopoids
Residual regional richness
C- Calanoids 40
D- Crustaceans
Local richness

11. Zooplankton show linear patterns of local and regional richness
Predictions
Local communities are open to invasion from the regional pool
Species interactions have little impact on invasion success

12. The importance of scale
What are the roles of local and regional processes in zooplankton communities?
Observational test
global patterns of local and regional richness
Experimental tests
measuring community invasibility
measuring dispersal rates
The importance of scale
modeling spread of invaders

18. Invasion experiment questions Shurin 2000. Ecology 81: 3074
Are zooplankton dispersal limited?
species will colonize the invasion treatment
What are the effects of relaxing dispersal limitation?
zooplankton diversity and biomass will increase
Does invasibility relate to native diversity?
invasibility will decline at high native diversity

19. Invasion experiment results
0.2
0.4
0.6
0.8 1
1.2
Exotic biomass
[log (ug/L) + 1] 1 2 3 4 5 6 7 8
Bird 1
Lab
L.A. 11
Hut
Norris
Ent.
Rock
Bird 2
Shaw
Upton
L.A. 12
% introduction
success

20. Why would more diverse communities be harder to invade
Why would more diverse communities be harder to invade? (Elton’s 1958 hypothesis)
Fewer potential invaders in regional pool
more likely a species is already present
Less available niche space
prediction: lower per invader success rate
prediction: lower invader biomass once established

21. Invasibility vs. native diversity2 4 6 8
Exotic biomass
(ug/L) 1
EXPERIMENT
% introduction
success
Native diversity
(Fisher’s alpha) 3
rs = -0.70
P < 0.025
rs = -0.57
P < 0.05

22. No effects of invasion on
total zooplankton diversity or biomass
biomass or extinction of native species
phytoplankton biomass

23. How important are interspecific interactions to invasion success?
treatment
Resistance
treatment
11 ponds
4 Ponds

24. Biological resistance to invasion
0.5 1
1.5 2
2.5
Exotic biomass
[log (ug/L) + 1] 3 4 5 6 7
Bird
Shaw
Upton
L.A.
% introduction
success
Resistance=
16X Invasion
4X Invasion

25. Conclusions from invasion experiment
Weak dispersal limitation
Dispersal does not limit biomass or diversity
Invasibility declines at high diversity
Interspecific interactions play a major role
big effect of resistance treatment
Suggests colonization >> extinction
for most species

27. Cohen and Shurin 2003, Oikos 103: 603
Experimental design: pools at 5, 10, 30 and 60m from 2 real ponds plus a non-dispersal limited control
Cohen and Shurin 2003, Oikos 103: 603

28. Fast colonization:
one new species
every four days

29. A paradox? Observational evidence: strong regional control
linear patterns of local and regional diversity
Experimental evidence: strong local control
resistance to invasion
strong species interactions
rapid dispersal

30. Theoretical and empirical resolution?
Facilitation versus inhibition
The effects of predators on local and regional coexistence
Shurin and Allen American Naturalist 158: 624
Shurin Ecology 82: 3404
The influence of scale
Modeling the spread of exotic species
Havel, Shurin and Jones Ecology  83: 3306
Shurin and Havel Biological Invasions 4: 431

34. Modeling spread of exotics
with John Havel and Jack Jones (Ecology 83:3306)
How can we use spread to estimate
dispersal at broad scales?
Is invasion limited by dispersal or
local constraints?

35. Modeling invasion probability
surface area
temperature
conductivity
total nitrogen
total phosphorus
chlorophyll
volatile solids
non-volatile solids
secchi depth
turbidity
How do we include dispersal potential?
invasion
probability +
local
variables 
dispersal
potential

36. Modeling dispersal potential from spatial position
P 1T
P 2T * *
source 1
source 2
target
d1,T
d2,T
# propagules = P 1T + P 2T
What is the shape of the dispersal function?

37. # propagules = e(-d/a) The shapes of different dispersal functions
0.2
0.4
0.6
0.8 1 20 40 60 80
100
Distance (km)
# propagules
a=10 30
# propagules = e(-d/a)
What is the most likely value for a?

38. The likelihood profile approach to estimate a47 48 49 50 51 52 20 40 60 80
100 a
-2 log likelihood
1995
The most likely a = 17

39. The dispersal function for 1995
Pi = exp(-d/17) 20 40 60 80
100
0.03
0.06
0.09
0.12
# dispersal events
Distance (km)

40. Do spatial or local models best predict invasion?
probability +
local
variables 
dispersal
potential
1995 10 20 30 40 50 60 70 80 90
local
dispersal
local +
AIC

41. Do spatial or local models best predict invasion?
probability +
local
variables 
dispersal
potential 90 80 70
local 60
dispersal 50
AIC
local +
dispersal 40 30 20 10
1993
1994
1995
1996
year

42. Conclusions from invasion model
Dispersal of Daphnia lumholtzi localized up to km
Invasion limited by local environment and dispersal
Local control more important than dispersal

43. How does dispersal ability vary among aquatic taxa
How does dispersal ability vary among aquatic taxa? How does dispersal ability affect patterns of diversity at different scales? with Karl Cottenie and Helmut Hillebrand (Ecology Letters, in review)

44. How should β-diversity change with distance?
bad dispersers
good dispersers
Tilman, Lehman and Kareiva Spatial Ecology

45. β-diversity versus distance for different taxa

46. Vertebrates show higher β-diversity, clumpier distributions
Slope (β vs. distance)

47. Conclusions Zooplankton show linear local-regional richness patterns
Experiments found strong invasion resistance, rapid dispersal
Importance of dispersal increases with
distance and body size