The Meaning of Biodiversity

1. The Meaning of Biodiversity William Silvert IPIMAR-INIAP, Lisboa, Portugal silvert@ipimar.pt

2. The Politics of Conservation • Conservation originally meant maintenance of important(?) species. • Then it came to mean maintenance of every species. • This is simply unrealistic. • So now we are trying to measure and conserve something called biodiversity.

3. What is Biodiversity? • We all want to conserve biodiversity. • Everyone can define biodiversity. • These definitions are often: • Different and inconsistent • Vague and imprecise • Difficult or impossible to implement • Distorted by bias or ignorance.

4. Realistic Expectations • We cannot conserve every species. • Population growth and industrialisation and war inevitably lead to loss of habitat and risk of species extinction. • So we may not want to play G*d, but we have to fight battles that we can win, and pick our conservation goals carefully.

5. Triage • Physicians working in the battlefield divide casualties into three groups: • Likely to recover • Likely to die • Responsive to medical care • Species at risk are similar: • Likely to persist • Likely to go extinct • Worth fighting for.

6. Setting Value on Species • Are all species of equal value? • Society will never accept the loss of a species of great whale to save several species of amphipod or nematode or copepod. • We have to be willing to assign values to different species in order to set realistic conservation priorities.

7. What makes a species valuable? • Charisma! • Does it have intrinsic value to man? • What does it do (what is its role)? • How important is this role, and could some other species replace it? • Is it unique?

8. Charisma • Some species have to be conserved, this is a social imperative: • Great whales • Fuzzy white harp seals • Pandas • Conservation of charismatic species has little to do with ecology.

9. Intrinsic Value to Man • Some species need to be conserved because they are a key part of our ecosystem, whether or not they are very important in general ecological terms. • Examples include food fish like cod and their major prey species (e.g., capelin and sand eel), and valuable species like lobster and sturgeon.

10. What Does it Do? • Some species have obvious and vital ecological roles: • Polar Bears • Calanus finmarchicus • Amphipods • Earthworms • Alligators • Dung beetles

11. Can it be Replaced? • If certain key species are exterminated the entire ecosystem will change. • If we eradicate one species of copepod or dung beetle, will another fill its place? • If so, how long will replacement take? • Will the replacement be a good fit, both ecologically and in human terms?

12. Uniqueness and Speciation • Some species are unique – there is nothing like them, and nothing to replace them. • Other species are stamped out in “speciation factories”, like archipelagos and other “biodiversity hotspots” where we find lots of similar but separate species.

13. Unforeseen Effects • When venturing into the unknown there is always the risk of the unexpected. • We could lose a species whose toxin contains the cure for cancer. • A replacement species might be the vector for a dangerous parasite. • Anything can happen – extinction, like life, is a gamble.

14. Summary • We cannot hope to conserve all species. • Concepts of biodiversity should serve as guides to social and political action. • Anything we do involves risk, and while we try to minimise risk, we cannot avoid it. • We have to mix idealism with pragmatism.