Andrew Gonzalez Canada Research Chair

1. Understanding the impacts of extinction: the next step for biodiversity research Andrew Gonzalez Canada Research Chair Department of Biology

2. 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 change…show no evidence of declining over time, or are increasing in intensity.” Extinction rates are 100-1000 times higher than the background rate

3. 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

4. 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

5. 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

6. ? ? Ecosystem Function Diversity gradients Is Biodiversity Loss a Component of Global Change? Hypothesis: Does diversity loss affect ecosystem function? Anthropogenic Anthropogenic Ecosystem Ecosystem Disturbance Disturbance Function Extinction

7. "Redundancy" "Complementarity" Ecological function Ecological function Articulating the Hypothesis Simple 'models' proposed (circa 1993) for the relation between diversity and ecosystem function diversity diversity

8. Cedar Creek, Minnesota Experimental Evidence Experiments have been performed at small spatial and temporal scales and assume way the ‘dynamics’ of extinction.

9. Ecosystem Anthropogenic Anthropogenic Function Disturbance Disturbance ? Extinction Getting Real Hypothesis: Extinctions are a consequence of disturbance and can amplify the effects of disturbance. Ecosystem Function Diversity

10. 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

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. Extinction is a highly nonlinear process (perhaps cascading) with inherent response delays. Current experimental protocols based on “random species assembly” do not mimic extinction.

12. Studying the lagged effects of extinction: habitat loss • A complementary ‘dynamic’ approach: • Allows the study of the extinction process 50cm 20cm² 200cm² 50cm Fragments Control Replicated experimental landscapes of natural (micro) ecosystems

13. Secondary biomass Species richness 27 <40% 9 <68% 22 8 7 17 Species richness (# spp) 6 Secondary biomass (mg) 5 12 4 7 3 2 2 1 0 2 4 6 8 10 12 0 0 2 4 6 8 10 12 Time after fragmentation An Example of an Extinction ‘Debt’ Controls Fragments

14. “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

15. 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.