andrew gonzalez canada research chair
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Understanding the impacts of extinction: the next step for biodiversity research. Andrew Gonzalez Canada Research Chair. Department of Biology. Key Message. - PowerPoint PPT PresentationTRANSCRIPT
Andrew GonzalezCanada Research Chair
Department of Biology
Understanding the impacts of extinction: the next step for
biodiversity research
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“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 change…show no evidence of declining over time, or are increasing in intensity.”
Key Message
Extinction rates are 100-1000 times higher than the background rate
3
MES: Biodiversity Synthesis
• In ~15 yrs of BD research we have learnt a great deal.
• BD loss has happened, is ongoing.
• BD matters for ecosystem functioning.
• A deeper understanding of of BD loss is required--more science.
• High uncertainty
• Conflicting human and ecological needs.
4
“A mismatch exists between the dynamics of changes in natural systems and human responses to those changes.” pg21 MABS
Key Issue for future biodiversity research
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Functional Effects of Biodiversity Loss
Characteristics:
1. Ignorance of mechanism
2. Potential catastrophic
costs
3. Relatively modest benefits
4. Low subjective probability
5. Internal experience of
costs
6. External transfer of
benefits
7. Collective risk
8. Latency (lagged effects)
9. Irreversibility
6
Hypothesis: Does diversity loss affect ecosystem function?
AnthropogenicDisturbance
EcosystemAnthropogenicDisturbance
EcosystemFunction
Extinction
Is Biodiversity Loss a Component of Global Change?
?
EcosystemFunction
Diversity gradients
?
7
Simple 'models' proposed (circa 1993) for the relation between diversity and ecosystem function
"Redundancy" "Complementarity"
Ecological function
Ecological function
diversity diversity
Articulating the Hypothesis
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Experiments have been performed at small spatial and temporal scales and assume way the ‘dynamics’ of extinction.
Experimental Evidence
Cedar Creek, Minnesota
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Hypothesis: Extinctions are a consequence of disturbance and can amplify the effects of disturbance.
Ecosystem
Function
Diversity
Getting Real
Anthropogenic
Disturbance
EcosystemAnthropogenic
DisturbanceFunction
Extinction
?
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Biodiversity Loss: why response mismatches?
Characteristics:
1. Ignorance of mechanism
2. Potential catastrophic
costs
3. Relatively modest benefits
4. Low subjective probability
5. Internal experience of
costs
6. External transfer of
benefits
7. Collective risk
8. Latency (lagged effects)
9. Irreversibility
11
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.
Current experimental protocols based on “random species assembly” do not mimic extinction.
Extinction is a highly nonlinear process (perhaps cascading) with inherent response delays.
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Studying the lagged effects of extinction: habitat loss
50
cm
20cm²
Control Fragments
50cm
200cm²
A complementary ‘dynamic’ approach:
• Allows the study of the extinction process
Replicated experimental landscapes of natural (micro) ecosystems
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An Example of an Extinction ‘Debt’
Fragments
Controls
Time after fragmentation
0
1
2
3
4
5
6
7
8
9
0 2 4 6 8 10 12
Seco
ndary
bio
mass
(m
g)
<68%
2
7
12
17
22
27
0 2 4 6 8 10 12
Speci
es
rich
ness
(#
spp) <40%
Species richness Secondary biomass
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Characteristics:
1. Ignorance of mechanism
2. Potential catastrophic
costs
3. Relatively modest benefits
4. Low subjective probability
5. Internal experience of
costs
6. External transfer of
benefits
7. Collective risk
8. Latency (lagged effects)
9. Irreversibility
“A mismatch exists between the dynamics of changes in natural systems and human responses to those changes.” pg21 MABS
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• 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.
Conclusions
• Significant progress in biodiversity research to date, but still only a poor understanding of the functional effects of extinction.
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