Chapter 56

1. Chapter 56 Conservation Biology and Restoration Ecology

2. Biodiversity • The current rate of species extinction is high and is largely a result of ecosystem degradation by humans • Humans are a huge threat to Earth’s biodiversity

3. Genetic diversity in a vole population Species diversity in a coastal redwood ecosystem Community and ecosystem diversity across the landscape of an entire region Levels of Biodiversity • Biodiversity has three main components • Genetic diversity • Species diversity • Ecosystem diversity

4. Diversity • Genetic diversity comprises • The genetic variation within a population • The genetic variation between populations • Species diversity • Is the variety of species in an ecosystem or throughout the biosphere • Ecosystem diversity • Identifies the variety of ecosystems in the biosphere

5. Endangered species • Is one that is in danger of becoming extinct throughout its range • Threatened species • Are those that are considered likely to become endangered in the foreseeable future

6. (a) Philippine eagle (b) Chinese river dolphin (c) Javan rhinoceros • Harvard biologist E. O. Wilson has identified the Hundred Heartbeat Club • Species that number fewer than 100 individuals and are only that many heartbeats from extinction

7. Biodiversity (affect on Human Welfare) • Biophilia: Our sense of connection to nature and to other life forms • Allows us to recognize the value of biodiversity for its own sake • The loss of species means the loss of genes and genetic diversity • The enormous genetic diversity of organisms on Earth has the potential for great human benefit

8. Benefits of Species and Genetic Diversity • Many pharmaceuticals contain substances originally derived from plants Rosy periwinkle is a source of anti-cancer drugs

9. Ecosystem Services • Ecosystem services encompass all the processes through which natural ecosystems and the species they contain help sustain human life on Earth • Ecosystem services include • Purification of air and water • Detoxification and decomposition of wastes • Cycling of nutrients • Pollination of crops • Moderation of weather extremes • Etc., etc., etc.

10. Four Major Threats to Biodiversity • Most species loss can be traced to four major threats • Habitat destruction • Introduced species • Overexploitation • Disruption of “interaction networks”

11. Habitat Destruction • Human alteration of habitat is the single greatest threat to biodiversity throughout the biosphere

12. Madagascar Deforestation Movie

13. Many natural landscapes have been broken up • Fragmenting habitat into small patches • Habitat fragmentation and destruction leads to loss of biodiversity Fragmented forest habitat in Mount Hood National Forset

14. Habitat fragmentation in the foothills of Los Angeles

15. Introduced Species • Introduced species-Are those that humans move from the species’ native locations to new geographic regions

16. (a) Brown tree snake, intro- duced to Guam in cargo (b) Introduced kudzu thriving in South Carolina • Introduced species that gain a foothold in a new habitat usually disrupt their adopted community Kudzu: Native to Japan and China, kudzu was introduced into the US as an ornamental and for erosion control. It can grow as much as a foot-a-day.

17. The Vine That Ate the South Kudzu

18. Overexploitation • Overexploitation refers generally to the human harvesting of wild plants or animals • At rates exceeding the ability of populations of those species to rebound

19. The fishing industry • Has caused significant reduction in populations of certain game fish Bluefin tuna auction in Japan fish market http://www.montereybayaquarium.org/cr/SeafoodWatch/web/sfw_regional.aspx?region_id=0 (seafood guide)

20. Disruption of Interaction Networks • The extermination of keystone species by humans can lead to major changes in the structure of communities Pollinating flying fox Urchin munching sea otter

21. Population Conservation • Population conservation focuses on • population size • genetic diversity • critical habitat • Biologists focusing on conservation at the population and species levels follow two main approaches • Small-population model approach • Declining population approach

22. Small-Population Approach • Conservation biologists who adopt the small-population approach • Study the processes that can cause very small populations finally to become extinct

23. Small population Genetic drift Inbreeding Lower reproduction Higher mortality Loss of genetic variability Reduction in individual fitness and population adaptability Smaller population The Extinction Vortex • A small population is prone to positive-feedback loops that draw the population down an extinction vortex

24. The key factor driving the extinction vortex • Is the loss of the genetic variation necessary to enable evolutionary responses to environmental change

25. Case Study: The Greater Prairie Chicken and the Extinction Vortex • Populations of the greater prairie chicken were fragmented by agriculture and later found to exhibit decreased fertility • As a test of the extinction vortex hypothesis scientists imported genetic variation by transplanting birds from larger populations

26. EXPRIMENT 200 Researchers observed that the population collapse of the greater prairie chicken was mirrored in a reduction in fertility, as measured by the hatching rate of eggs. Comparison of DNA samples from the Jasper County, Illinois, population with DNA from feathers in museum specimens showed that genetic variation had declined in the study population. In 1992, researchers began experimental translocations of prairie chickens from Minnesota, Kansas, and Nebraska in an attempt to increase genetic variation. 150 Number of male birds 100 50 0 1970 1975 1980 1985 1990 1995 2000 RESULTS After translocation (blue arrow), the viability of eggs rapidly improved, and the population rebounded. Year (a) Population dynamics 100 90 80 70 60 Eggs hatched (%) 50 CONCLUSION The researchers concluded that lack of genetic variation had started the Jasper County population of prairie chickens down the extinction vortex. 40 30 1980-84 1985-89 1990 1993-97 1970-74 1975-79 Years (b) Hatching rate • The declining population rebounded • Confirming that it had been on its way down an extinction vortex

27. Minimum Viable Population Size • The minimum viable population (MVP) • Is the minimum population size at which a species is able to sustain its numbers and survive • A population viability analysis (PVA) • Predicts a population’s chances for survival over a particular time • Effective population size • Based on number of males and females that successfully breed…so smaller than the actual total population count. • Effective population size is used to estimate MVP

28. Declining-Population Approach • The declining-population approach • Focuses on threatened and endangered populations that show a downward trend, regardless of population size • Emphasizes the environmental factors that caused a population to decline in the first place

29. Steps for Analysis and Intervention • The declining-population approach • Requires that population declines be evaluated on a case-by-case basis • Involves a step-by-step proactive conservation strategy. (A do-something-before-it’s-too-late philosophy)

30. (a) A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine. (b) Forest that can sustain red-cockaded woodpeckers has low undergrowth. (c) Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds. Case Study: Decline of the Red-Cockaded Woodpecker • Red-cockaded woodpeckers • Require specific habitat factors for survival (they like habitat with minimal undergrowth and a good supply of optimal nesting trees) • Had been forced into decline by habitat destruction

31. In a study where breeding cavities were constructed … new breeding groups formed only in these sites • On the basis of this experiment • A combination of habitat maintenance and excavation of new breeding cavities has enabled a once-endangered species to rebound

32. Landscape Structure and Biodiversity • The structure of a landscape can strongly influence biodiversity

33. (a) Natural edges. Grasslands give way to forest ecosystems in Yellowstone National Park. (b) Edges created by human activity. Pronounced edges (roads) surround clear-cuts in this photograph of a heavily logged rain forest in Malaysia. Fragmentation and Edges • The boundaries, or edges, between ecosystems are defining features of landscapes • As habitat fragmentation increases and edges become more extensive, biodiversity tends to decrease

34. Habitat fragmentation effects

35. Fragmented Forest

36. Sprawl Sprawl fragments wildlife habitat, increasing the amount of development-associated species (e.g., white-tailed deer, Canada goose), at the expense of the more rare development-sensitive species (e.g., eastern bluebird, box turtle).

37. Size: Population StabilityPopulations are typically more stable and sustainable and less susceptible to local extinction in large patches than small patches.

38. ConnectivitySpecies movement among habitat patches can be facilitated through the protection of discrete spatial features such as stepping stones and linkages .

39. Connectivity:   IsolationSmall patches that are connected to other patches generally are more ecologically viable than isolated patches. Species within an isolated habitat patch are highly susceptible to disturbance and degradation from surrounding land uses because species movement (to and from the patch) is limited.

40. Connectivity:   InterconnectednessInterconnectedness is an important feature of networks, as it facilitates species movement among patches. Small interconnected patches provide cover, resting, and foraging habitats for animals en route to larger habitat patches. But, a network that is designed for connectivity but ignores other principles may have too much linear habitat and edge.

41. Corridors That Connect Habitat Fragments • A movement corridor • Is a narrow strip of quality habitat connecting otherwise isolated patches • They promote dispersal and help sustain populations

42. In areas of heavy human use • Artificial corridors are sometimes constructed Wildlife bridge in Banff

43. Establishing Protected Areas • Protected areas are established to slow the loss of biodiversity • A lot of the focus on establishing protected areas has been on hot spots of biological diversity

44. Terrestrial biodiversity hot spots Equator Biodiversity Hot Spots • A biodiversity hot spot is a relatively small area with an exceptional concentration of endemic species (specific confined to a certain geographic area) and a large number of endangered and threatened species

45. Rain Forest

46. Philosophy of Nature Reserves • Nature reserves are biodiversity islands • In a sea of habitat degraded to varying degrees by human activity • One argument for extensive reserves • Is that large, far-ranging animals with low-density populations require extensive habitats

47. 0 50 100 Kilometers 43 Yellowstone R. Gallatin R. Madison R. Montana 42 Wyoming Yellowstone National Park Montana Shoshone R. Idaho 41 Grand Teton National Park Biotic boundary for short-term survival; MVP is 50 individuals. Snake R. 40 Biotic boundary for long-term survival; MVP is 500 individuals. Idaho Wyoming • Often the size of reserves is smaller than the actual area needed to sustain a population

48. Yellowstone-to-Yukon initiative

49. WWF “Heart of Borneo” initiative http://www.worldwildlife.org/what/wherewework/borneo/WWFBinaryitem16012.pdf

50. World’s longest insect Only lungless frog