What are the causes and consequences of variation in diversity?
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What are the causes and consequences of variation in diversity? What are the causes and consequences of variation in diversity? How is diversity related to temporal variability? stability diversity History of ideas on diversity and stability Wild speculation- Elton 1958 MacArthur 1955

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What are the causes and consequences of variation in diversity?

How is diversity related to temporal variability?


Slide3 l.jpg

stability diversity?

diversity

History of ideas on diversity and stability

  • Wild speculation-

    • Elton 1958

    • MacArthur 1955

“Stability increases as the number of links increases. If the number of prey species for each species remains constant, an increase in the number of species in the community will increase the stability.”

-MacArthur 1955


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stability diversity?

diversity

History of ideas

  • Math defies intuition-

    • May 1973

    • Gardner and Ashby 1970

More species = greater chance of including unstable

combinations of strong interactions ->

extinctions and fluctuations

if interaction strength is uniformly distributed


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stability diversity?

diversity

History of ideas

  • The role of interaction strength

    • Yodzis 1981

    • McCann et al. 1998

    • Berlow 1999

“Early data unequivocally indicate that distributions of interaction strength are strongly skewed toward weak interactions. It seems, then, that weak interactions may be the glue that binds natural communities together”

-McCann et al. 1998Nature


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stability diversity?

stability

stability

diversity

diversity

diversity

History of ideas

  • Wild speculation-

  • Math defies intuition-

  • The role of interaction strength-


How are diversity and stability related in nature l.jpg
How are diversity and stability related in nature? diversity?

What can species-time relations tell us

about diversity and stability?


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Questions? diversity?

  • How is diversity related to community temporal stability?

    • Model

  • How do diversity and stability covary in lake zooplankton assemblages?

    • Data

  • How is diversity related to environmental variability?

    • Data


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35 diversity?

30

Daily richness

25

20

10

20

30

40

50

60

70

80

90

100

50

45

Cumulative richness

40

10

20

30

40

50

60

70

80

90

100

Time

How do we measure stability?Species turnover

a = daily richness

z = turnover

ST= long-term richness

ST = aTz


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How do species partition time… diversity?if diversity is driven by history ?

Shurin 2007 Oikos 116: 957


How do species partition time if diversity is driven by history11 l.jpg
How do species partition time… diversity?if diversity is driven by history ?

total richness

time

time

time

Shurin 2007 Oikos 116: 957


How do species partition time if diversity is driven by history12 l.jpg
How do species partition time… diversity?if diversity is driven by history ?

total richness

time

time

time

turnover

daily richness

total richness

total richness

Shurin 2007 Oikos 116: 957


How do species partition time if diversity prevents colonization l.jpg
How do species partition time… diversity?if diversity prevents colonization ?

total richness

time

time

time

turnover

daily richness

total richness

total richness

Shurin 2007 Oikos 116: 957


How do species partition time if diversity facilitates colonization l.jpg
How do species partition time… diversity?if diversity facilitates colonization ?

total richness

time

time

time

turnover

daily richness

total richness

total richness

Shurin 2007 Oikos 116: 957


How do species partition time if environmental variability increases diversity l.jpg
How do species partition time… diversity?if environmental variability increases diversity?

total richness

time

time

time

turnover

daily richness

total richness

total richness

Shurin 2007 Oikos 116: 957


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Model predictions: diversity?

Correlation with long-term richness

Shurin 2007 Oikos 116: 957


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And the data say… diversity?

Toolik

SE AK

ELA

Quebec

Kodiak

Dorsett

Lake Geneva

Washington

Wisconsin

36 lakes

483 lake-years

5,364 samples


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Daily, annual and inter-annual richness diversity?

Shurin et al. 2007 Ecology Letters 10: 127


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Richness and turnover diversity?

Shurin et al. 2007 Ecology Letters 10: 127


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Richness and turnover diversity?

Shurin et al. 2007 Ecology Letters 10: 127


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Richness and turnover diversity?

Shurin et al. 2007 Ecology Letters 10: 127


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Conclusions diversity?

  • Feedbacks among diversity, invasion, extinction and the environment influence different aspects of species-time

  • Zooplankton show scale-dependent patterns

    • positive correlations within the temperate zone

    • negative correlations across latitudes


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Environmental stability and diversity- diversity?a double edged sword

  • Abiotic variability can either increase or decrease coexistence

  • Storage effects vs. geometric mean fitness

What is the net effect of environmental variation on diversity?



The data set l.jpg
The data set Ontario


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The data set Ontario

surface temperature

bottom temperature

chlorophyll a

total nitrogen

total phosphorus

maximum O2

minimum O2

conductivity

pH

DOC

+ zooplankton species

X 10 variables


The data set27 l.jpg

surface temperature Ontario

bottom temperature

chlorophyll a

total nitrogen

total phosphorus

maximum O2

minimum O2

conductivity

pH

DOC

+ zooplankton species

X 10 variables

The data set

X 53 lakes


The data set28 l.jpg

surface temperature Ontario

bottom temperature

chlorophyll a

total nitrogen

total phosphorus

maximum O2

minimum O2

conductivity

pH

DOC

+ zooplankton species

X 10 variables

The data set

X 53 lakes

X 1,042 years

5,932 monthly samples


How do we partition environmental variability among time scales l.jpg
How do we partition environmental variability among time scales?

  • Multiplicative model of variance decomposition:

    • Xt = XltAtStEt

      • Xlt = long-term mean

      • At = inter-annual component (XA/Xlt)

      • St = seasonal component (XM/XA)

      • Et = event or unpredictable component


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How do we partition environmental variability among time scales?

  • Multiplicative model of variance decomposition:

    • Xt = XltAtStEt

      • Xlt = long-term mean

      • At = inter-annual component (XA/Xlt)

      • St = seasonal component (XM/XA)

      • Et = event or unpredictable component

}

Standard Deviation

measures variance

on each

time scale




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Interannual = mean

0.14

Seasonal =

0.008

Residual =

0.02









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How does variability relate to zooplankton diversity? mean

  • Long-term mean

  • Interannual variability

  • Seasonal variability

  • Residual (unpredictable) variability


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Zooplankton species richness and meanmean environmental conditions


Zooplankton species richness and interannual variability l.jpg
Zooplankton species richness and meaninterannual variability


Zooplankton species richness and seasonal variability l.jpg
Zooplankton species richness and meanseasonal variability


Zooplankton species richness and residual variability l.jpg

Residual variability mean

16

16

14

14

12

12

zooplankton richness

10

10

8

8

6

6

4

4

0.0

0.1

0.2

0.3

0.4

0.5

-2.0

-1.5

-1.0

bottom temperature

ln(TP)

Zooplankton species richness and residual variability


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Interannual and residual variation are better predictors of diversityaverage conditions and seasonality- not so much


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Conclusions diversity

  • Diversity mostly increases with greater thermal variability but declines with chemical instability

  • Environmental variability (especially interannual and unpredictable) are more important for diversity than average conditions


Increasing frequency of extreme variation easterling et al 2000 science l.jpg
Increasing frequency of extreme variation diversityEasterling et al. 2000 Science

birth of Jon


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Thanks diversity

  • Helmut Hillebrand

  • Monika Winder

  • Rita Adrian

  • Bill Keller

  • Blake Matthews

  • Andrew Paterson

  • Michael Paterson

  • Bernadette Pinel-Alloul

  • Jim Rusak

  • Shelley Arnott

  • Allyson Longmuir

  • Norm Yan


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