Lecture 14: Conservation biology

1. Lecture 14: Conservation biology EEES 3050

2. Conservation biology • …biology of population decline and scarcity. • Two paradigms: • Small populations (local) • Declining populations (regional)

3. Small population paradigm • Many (most) species are rare. • Issues include: • Population genetics • Demographic models of extinction. • Extinction vortex…

4. Extinction vortex

5. What causes a species to go extinct? • On the other hand… what does it take for a species to maintain existence? • Minimum Viable population • What causes a species to go extinct? • Demographic stochasticity • Genetic stochasticity • Environmental stochasticity

6. Demographic stochasticity • Random variation in birth and death rates. • At small population sizes each individual may be important. • Not thought to be critically important unless population size less than 50 individuals.

7. Genetic Stochasticity • Genetic diversity is the key to fitness. • Thus loss of heterogeneity often leads to loss in fitness. • Genetic diversity lost by drift and inbreeding. • Again, typically a problem of very small populations.

8. Environmental stochasticity • Changes from outside the population • Abiotic • Catastrophic events • Lack of catastrophic events? • Biotic • Invasive species, disease.

9. What does it mean to be rare? • Three factors determine rarity: • Geographic distribution • Habitat specificity • Population size Spotted Darter

10. Types of rarity

11. Declining population paradigm • How do you detect, diagnose and halt a population decline? • 4 causes of extinction: “Evil Quartet” • Overkill • Habitat destruction and fragmentation • Introduced species • Chains of extinction Suggested reading: Population Bomb by Paul Ehrlich

12. Overkill • Kind of obvious! • Examples: • Elephants due to tusks. • Over harvesting fish • Hunting of birds (e.g. passenger pigeon) • Who uses the resources in their absence?

13. Habitat destruction and fragmentation • What is habitat destruction? • Land-use conversion • Forest to field • Urban sprawl • Habitat fragmentation? • Not just loss of habitat • Loss of connectivity.

14. Fragmentation: Simple Example

15. Fragmentation: Simple Example

16. What additional impacts are associated with habitat fragmentation? • More edge areas • Populations more disconnected • What can be done about fragmentation? • Corridors

17. Introduced species Skinner: Well, I was wrong. The lizards are a godsend. Lisa: But isn't that a bit short-sighted? What happens when we're overrun by lizards? Skinner: No problem. We simply release wave after wave of Chinese needle snakes. They'll wipe out the lizards. Lisa: But aren't the snakes even worse? Skinner: Yes, but we're prepared for that. We've lined up a fabulous type of gorilla that thrives on snake meat. Lisa: But then we're stuck with gorillas! Skinner: No, that's the beautiful part. When wintertime rolls around, the gorillas simply freeze to death.

18. Introduced species • Examples: • Nile perch introduced into Lake Victoria and caused the extinction of over 200 endemic species. • Red fox introduced into Australia and caused the extinction of numerous mammals. • Zebra mussels in the U.S.?

19. Chains of extinction • Sometimes other species depend on those species that are already lost. • Examples: • Loss of predators when prey disappears • Extinction of Forest eagle of New Zealand • Loss of habitat when commensals disappear • Prairie dogs - black footed ferret, burrowing owls, mountain plovers, golden eagles, swift fox, and ferruginous hawks • Gopher tortoise - frogs, turtles, juvenile tortoises, poisonous and non-poisonous snakes, many small mammals, and even some birds such as the Florida scrub-jay and burrowing owl.

20. Reserve Design • What do you need to consider when you want to establish a preserve or protected area? • What are the objectives? • Individuals species? • Community types? • How to manage? • Active management • Passive management

21. Conservation Planning

22. Systematic conservation planningMargules & Pressey. 2000. Nature • What is the main purpose of conservation? • Separate elements of biodiversity from processes that threaten their existence in wild. • What objectives must a “good” reserve fulfill? • Representativeness • Persistence

23. Characteristics of systematic conservation planning • Choices about features to be used as surrogates for biodiversity • Based on explicit goals • Recognizes value of other existing reserves • Use explicit method for determining new reserves

24. How does science influence the process? • Theory • Solutions • Review effectiveness

25. Stages of systematic conservation planning • Measure and map biodiversity • Identify goals • Review existing reserves • Select additional reserves • Implement action • Manage and monitor

26. 1 – Measure and map biodiversity

27. 1 – Measure and map biodiversity • Can’t measure everything… What to measure? • Surrogates • Ecosystem functions • Environmental heterogeneity as estimator

28. 2 – Identify conservation goals • Need specific, quantitative targets • ‘More equals better’ not helpful • Example of goals: • Species x, y, and z must be included. • Preserve must include ecosystem types a, b and c. • Preserve must be linked to other conservation areas.

29. 2 – Identify conservation goals • Use of theory… • Population demographics • Biogeography • Metapopulation • Succession • Source-sink • Effects of habitat modification • Landscape genetics

30. 3 – Review existing reserves • GAP Analysis • Some aspects missing • Likelihood of extinction • Natural dynamics and long term prospects

31. 4 – Select additional reserves • Use of selection algorithms • i.e. a set of rules to determine choices • 5 constraints • Irreplaceability • Costs • Commitments • Masks (areas to exclude) • Preferences

32. 5 – Implement conservation action • Implementation may change everything • Three important decisions • What is the most feasible/appropriate management for a location? • What if a particular choice is degraded? • What is the order? • Two important issues to help answer questions. • Irreplaceability • Vulnerability to risk

33. 6 – Management and monitoring • Establishing a reserve is only the beginning. • Each site now requires a systematic planning process.

34. How to preserve the Northern Spotted Owl? • Basics • Uses 1-4 sq. miles of old growth forest. • Logging has destroyed most old growth. • Questions: • What type of habitat does an owl actually use? • How much do they need?

35. Owl use of old growth forest.

36. Northern spotted owl • Results of research • Much of “protected” land is not suitable habitat. • To preserve this species, research suggests that a large part of remaining old-growth forests in the Pacific Northwest must be preserved. • Now a responsibility of the general public.

37. State of the science of conservation biology • Personal thoughts… • Often anecdotal. • Limited in quantitative methods/analysis. • Obscured by personal subjectivity. • Final example: Exxon Valdez (spill in 1989) • What has happened to the bird communities since spill?

38. Exxon Valdez • Observations: • Oil spill has caused damage to the environment and to many species. • Question: what are the long term impacts? • Hypothesis: Areas that were impacted by the Valdez spill will have lower number of bird species than areas not impacted (control).

39. Exxon Valdez: Results

40. Exxon Valdez: Further comments • This was just the effect on the number of birds in these areas. • What other bird effects could still be persistent? • Many other species were impacted. • Pink salmon appear to not show continued long-term impacts • Harlequin ducks have had adverse effects (as of 1998). What do they eat?