Andrew Gonzalez

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Understanding the impacts of extinction the next
step for biodiversity research
Andrew Gonzalez Canada Research Chair
Department of Biology
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Key Message
Changes in biodiversity due to human activities
were more rapid in the past 50 years than at any
time in human history, and the drivers of
changeshow no evidence of declining over time,
or are increasing in intensity.
Extinction rates are 100-1000 times higher than
the background rate
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MES Biodiversity Synthesis

• BD loss has happened, is ongoing.

• BD matters for ecosystem functioning.

• In 15 yrs of BD research we have learnt a great
  deal.

• A deeper understanding of of BD loss is
  required--more science.

• Conflicting human and ecological needs.

• High uncertainty

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Key Issue for future biodiversity research
A mismatch exists between the dynamics of
changes in natural systems and human responses to
those changes. pg21 MABS
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Functional Effects of Biodiversity Loss
Characteristics

• Ignorance of mechanism
• Potential catastrophic costs
• Relatively modest benefits
• Low subjective probability
• 5. Internal experience of costs
• External transfer of benefits
• Collective risk
• Latency (lagged effects)
• Irreversibility

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Is Biodiversity Loss a Component of Global Change?
Hypothesis Does diversity loss affect ecosystem
function?
Anthropogenic
Ecosystem
Anthropogenic
Ecosystem
Disturbance
Disturbance
Function
Extinction
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Articulating the Hypothesis
Simple 'models' proposed (circa 1993) for the
relation between diversity and ecosystem function
diversity
diversity
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Experimental Evidence
Experiments have been performed at small spatial
and temporal scales and assume way the dynamics
of extinction.
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Getting Real
Hypothesis Extinctions are a consequence of
disturbance and can amplify the effects of
disturbance.
Ecosystem
Function
Diversity
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Biodiversity Loss why response mismatches?
Characteristics

• Ignorance of mechanism
• Potential catastrophic costs
• Relatively modest benefits
• Low subjective probability
• 5. Internal experience of costs
• External transfer of benefits
• Collective risk
• Latency (lagged effects)
• Irreversibility

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Example of a response mismatch Extinction debts
Extinction debt the difference between the
initial and final levels of diversity attained
long after the initial disturbance.
Extinction is a highly nonlinear process (perhaps
cascading) with inherent response delays.
Current experimental protocols based on random
species assembly do not mimic extinction.
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Studying the lagged effects of extinction
habitat loss

• A complementary dynamic approach
• Allows the study of the extinction process

50cm
20cm²
200cm²
50cm
Control
Fragments
Replicated experimental landscapes of natural
(micro) ecosystems
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An Example of an Extinction Debt
Controls
Fragments
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A mismatch exists between the dynamics of
changes in natural systems and human responses to
those changes. pg21 MABS
Characteristics

• Ignorance of mechanism
• Potential catastrophic costs
• Relatively modest benefits
• Low subjective probability
• 5. Internal experience of costs
• External transfer of benefits
• Collective risk
• Latency (lagged effects)
• Irreversibility

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Conclusions

• Significant progress in biodiversity research to
  date, but still only a poor understanding of the
  functional effects of extinction.

• It is imperative that we study the dynamics of
  extinction within the context of anthropogenic
  disturbance this is possible but new approaches
  are required.

• Without this knowledge it will be difficult to
  mitigate the functional consequences of future
  extinctions so clearly articulated in the
  Millenium Assessment.

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