Does ecology put pattern before process

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Does ecology put pattern before process?
Whats the difference between patterns and laws?
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What are the causes and consequences of
variation in diversity?
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What are the causes and consequences of
variation in diversity?
How is diversity related to temporal variability?
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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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History of ideas

• Math defies intuition-
• May 1973
• Gardner and Ashby 1970

More species greater chance of including
unstable combinations of strong interactions -gt
extinctions and fluctuations if interaction
strength is uniformly distributed
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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. 1998 Nature
But wait, what does strongly skewed mean? So
wonders Spencer Wood
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History of ideas

• Wild speculation-
• Math defies intuition-
• The role of interaction strength-

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How are diversity and stability related in nature?
What can species-time relations tell us about
diversity and stability?
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Questions?

• How is diversity related to community temporal
  stability?
• Model
• How do diversity and stability covary in lake
  zooplankton assemblages?
• Data

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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 timeif diversity is
driven by history ?
Shurin 2007 Oikos 116 957
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How do species partition timeif diversity is
driven by history ?
total richness
time
time
time
Shurin 2007 Oikos 116 957
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How do species partition timeif diversity is
driven by history ?
total richness
time
time
time
turnover
daily richness
total richness
total richness
Shurin 2007 Oikos 116 957
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How do species partition timeif diversity
prevents colonization ?
total richness
time
time
time
turnover
daily richness
total richness
total richness
Shurin 2007 Oikos 116 957
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How do species partition timeif diversity
facilitates colonization ?
total richness
time
time
time
turnover
daily richness
total richness
total richness
Shurin 2007 Oikos 116 957
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How do species partition timeif 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
Correlation with long-term richness
Shurin 2007 Oikos 116 957
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And the data say
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
Shurin et al. 2007 Ecology Letters 10 127
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Richness and turnover
Shurin et al. 2007 Ecology Letters 10 127
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Richness and turnover
Shurin et al. 2007 Ecology Letters 10 127
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Richness and turnover
Shurin et al. 2007 Ecology Letters 10 127
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How do temporal components of richness change
with latitude and area?
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Conclusions

• 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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How does environmental variability affect
diversity and stability?

• Abiotic variability can either increase or
  decrease coexistence
• Storage effects vs. geometric mean fitness
• Chesson and Huntley 1994 Am Nat 150 519

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How does environmental variability affect
diversity and stability? Clearwater Lake, Ontario
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How do we partition environmental variability
among time scales?

• A multiplicative model of variance decomposition
• Xt AtStEt
• At annual component
• St seasonal component
• Et event or unpredictable component

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The seasonal component
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The annual component as deviation from the
long-term mean
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(No Transcript)
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Total nitrogen has low seasonal variation
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Temperature has high seasonal variation
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Conductivity has high interannual variation
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How is diversity related to environmental
variation?

• Mean conditions vs. variability
• Variation on seasonal, annual, and interannual
  time scales

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Does ecology put pattern before process?
Whats the difference between patterns and laws?