This lecture will help you understand:

2. This lecture will help you understand: • The scope of Earth’s biodiversity • Background rates and mass extinction • Primary causes of biodiversity loss • The benefits of biodiversity • Conservation biology • Biodiversity conservation efforts

3. Central Case: Saving the Siberian tiger • The largest cat in the world • The Russian Far East mountains house the last remaining tigers • Nearly became extinct due to hunting, poaching and habitat destruction • International conservation groups saved the species from extinction • Research, education, zoos, and captive breeding programs

4. Biodiversity encompasses several levels • Humans are reducing Earth’s diversity of life • Biodiversity – sum total of all organisms in an area • Split into three specific levels: • Species diversity • Genetic diversity • Ecosystem diversity

5. Species diversity • Species Diversity = the number or variety of species in the world or in a particular region • Richness = the number of species • Evenness or relative abundance = extent to which numbers of individuals of different species are equal or skewed • Speciation generates new species and adds to species richness • Extinction reduces species richness

6. The taxonomy of species • Taxonomists = scientists who classify species • Physical appearance and genetics determines a species • Genera = related species are grouped together • Families = groups of genera • Every species has a two-part scientific name: genus and species

7. Subspecies: the level below a species • Subspecies = populations of species that occur in different areas and differ slightly from each other • Divergence stops short of separating the species • Subspecies are denoted with a third part of the scientific name Siberian tiger = Panthera tigris altaica Bengal tiger = Panthera tigris tigris

8. Genetic diversity • Encompasses the differences in DNA among individuals within species and populations • The raw material for adaptation to local conditions • Populations with higher genetic diversity can survive • They can cope with environmental change • Populations with low genetic diversity are vulnerable • To environmental change • Disease • Inbreeding depression = genetically similar parents mate and produce inferior offspring

9. Ecosystem diversity • Ecosystem diversity = the number and variety of ecosystems • Also encompasses differing communities and habitats • Rapid vegetation change and varying landscapes within an ecosystem promote higher levels of biodiversity

10. Some groups contain more species than others • Species are not evenly distributed among taxonomic groups • Insects predominate over all other life-forms • 40% of all insects are beetles • Groups accumulate species by • Adaptive radiation • Allopatric speciation • Low rates of extinction

11. Insects outnumber all other species

12. Measuring biodiversity is not easy • Out of the estimated 3 - 100 million species on Earth, only 1.7 - 2 million species have been successfully catalogued • Very difficult to identify species • Many remote spots on Earth remain unexplored • Small organisms are easily overlooked • Many species look identical until thoroughly examined • Entomologist Terry Erwin found 163 beetle species specialized on one tree species

13. Biodiversity is unevenly distributed • Living things are distributed unevenly across Earth • Latitudinal gradient = species richness increases towards the equator Canada has 30 - 100 species of breeding birds, while Costa Rica has more than 600 species

14. Latitudinal gradient has many causes • Climate stability, high plant productivity, and no glaciation • Tropical biomes support more species and show more species evenness • Diverse habitats increase species diversity • Human disturbance can increase habitat diversity • But only at the local level

15. Biodiversity losses and species extinction • Extinction = occurs when the last member of a species dies and the species ceases to exist • Extirpation = the disappearance of a particular population from a given area, but not the entire species globally • Can lead to extinction

16. Extinction is a natural process • Paleontologists estimate 99% of all species that ever lived are now extinct • Background rate of extinction = natural extinctions for a variety of reasons • 1 extinction per 1 to 10 million species for mammals and marine species • 1 species out of 1,000 mammal and marine species would go extinct every 1,000 to 10,000 years

17. Earth has experienced five mass extinctions • In the past 440 million years, mass extinctions have eliminated at least 50% of all species • After every mass extinction the biodiversity returned to or exceeded its original state

18. The current mass extinction is human caused • During this Quaternary period, we may lose more than half of all species • Hundreds of human-induced species extinctions, and multitudes of others, teeter on the brink of extinction • The current global extinction rate is 100 to 1,000 times greater than the background rate • This rate will increase tenfold in future decades due to human population growth and resource consumption

19. People have hunted species to extinction for millennia Extinctions followed human arrival on islands and continents

20. Current extinction rates are higher than normal • The Red List = an updated list of species facing high risks of extinctions • 23% of mammal species • 12% of bird species • 31 - 86% of all other species • Since 1970, 58 fish species, 9 bird species, and 1 mammal species has gone extinct • In the U.S., in the last 500 years, 236 animal and 17 plant species are confirmed extinct • Actual numbers are undoubtedly higher

21. Biodiversity loss is more than extinction • Decreasing numbers are accompanied by smaller species’ geographic ranges • Genetic, ecosystem, and species diversity are being lost. • The Living Planet Index summarizes trends in populations • Between 1970 and 2003, the Index fell by 30%

22. Biodiversity loss has many causes • Reasons for biodiversity losses are multifaceted, complex, and hard to determine • Factors may interact synergistically • Four primary causes of population decline are: • Habitat alteration • Invasive species • Pollution • Overharvesting • Global climate change now is the fifth cause

23. Habitat alteration causes biodiversity loss • The greatest cause of biodiversity loss • Farming simplifies communities • Grazing modifies the grassland structure and species composition • Clearing forests removes resources organisms need • Hydroelectric dams turn rivers into reservoirs upstream • Urbanization and suburban sprawl reduce natural communities • A few species (i.e., pigeons, rats) benefit from changing habitats

24. Habitat alteration has occurred in every biome Particularly in tropical rainforests, savannas, and tropical dry forests

25. Invasive species cause biodiversity loss • Introduction of non-native species to new environments • Accidental: zebra mussels • Deliberate: food crops • Island species are especially vulnerable • Invaders have no natural predators, competitors, or parasites • Cost billions of dollars in economic damage

26. Pollution causes biodiversity loss • Harms organisms in many ways • Air pollution degrades forest ecosystems • Water pollution adversely affects fish and amphibians • Agricultural runoff harms terrestrial and aquatic species • The effects of oil and chemical spills on wildlife are dramatic and well known • The damage to wildlife and ecosystems caused by pollution can be severe • But it tends to be less than the damage caused by habitat alteration or invasive species

27. Overharvesting causes biodiversity loss • Vulnerable species are large, few in number, long-lived, and have few young (K-selected species) • The Siberian tiger is hunted without rules and regulations • The early 1990s saw increased poaching because of powerful economic incentives • Many other species affected: Atlantic gray whale, sharks, gorillas Today the oceans contain only 10% of the large animals they once did

28. Climate change causes biodiversity loss • Emissions of greenhouse gases warms temperatures • Modifies global weather patterns and increases the frequency of extreme weather events • Increases stress on populations and forces organisms to shift their geographic ranges • Most animals and plants will not be able to cope

29. Warming has been the greatest in the Arctic The polar bear is being considered for the endangered species list

30. Biodiversity loss has a variety of causes

31. Biodiversity provides free ecosystem services • Provides food, shelter, fuel • Purifies air and water, and detoxifies wastes • Stabilizes climate, moderates floods, droughts, wind, temperature • Generates and renews soil fertility and cycles nutrients • Pollinates plants and controls pests and disease • Maintains genetic resources • Provides cultural and aesthetic benefits • Allows us to adapt to change The annual value of just 17 ecosystem services = $16 - 54 trillion per year

32. Biodiversity helps maintain ecosystem function • Biodiversity increases the stability and resilience of communities and ecosystems • Decreased biodiversity reduces a natural system’s ability to function and provide services to our society • The loss of a species affects ecosystems differently • If the species can be functionally replaced by others, it may make little difference • Extinction of a keystone species may cause other species to decline or disappear • “To keep every cog and wheel is the first precaution of intelligent tinkering” (Aldo Leopold)

33. Biodiversity enhances food security • Genetic diversity within crops is enormously valuable • Turkey’s wheat crops received $50 billion worth of disease resistance from wild wheat • Wild strains provide disease resistance and have the ability to grow back year after year without being replanted • New potential food crops are waiting to be used • Serendipity berry produces a sweetener 3,000 times sweeter than sugar

34. Some potential new food sources

35. Organisms provide drugs and medicines • Each year pharmaceutical products owing their origin to wild species generate up to $150 billion in sales • The rosy periwinkle produces compounds that treat Hodgkin's disease and leukemia

36. Biodiversity generates economic benefits • People like to experience protected natural areas, creating economic opportunities for residents, particularly in developing countries • Costa Rica: rainforests • Australia: Great Barrier Reef • Belize: reefs, caves, and rainforests • A powerful incentive to preserve natural areas and reduce impacts on the landscape and on native species • But, too many visitors to natural areas can degrade the outdoor experience and disturb wildlife

37. People value and seek out nature • Biophilia = connections that humans subconsciously seek with life • Our affinity for parks and wildlife • Keeping of pets • High value of real estate with views of natural lands • Nature deficit disorder = alienation from the natural environment • May be behind the emotional and physical problems of the young

38. Do we have ethical obligations to other species? • Humans are part of nature and need resources to survive • But, we also have conscious reasoning ability and can control our actions • Our ethics have developed from our intelligence and our ability to make choices • Many people feel that other organisms have intrinsic value and an inherent right to exist

39. Conservation biology responds to biodiversity loss • Conservation biology = devoted to understanding the factors that influence the loss, protection, and restoration of biodiversity • Arose as scientists became alarmed at the degradation of natural systems • An applied and goal-oriented science

40. Conservation scientists work at multiple levels • Conservation biologists integrate evolution and extinction with ecology and environmental systems • Design, test, and implement ways to mitigate human impacts • Conservation geneticists = study genetic attributes of organisms to infer the status of their population • Minimum viable population = how small a population can become before it runs into problems • Metapopulations = a network of subpopulations • Small populations are most vulnerable to extinction and need special attention

41. Island biogeography • Equilibrium theory of island biogeography = explains how species come to be distributed among oceanic islands • Also applies to “habitat islands” – patches of one habitat type isolated within a “sea” of others • Explains how the number of species on an island results from an equilibrium between immigration and extirpation • Predicts an island’s species richness based on the island’s size and distance from the mainland

42. Species richness results from island size and distance • Fewer species colonize an island far from the mainland • Large islands have higher immigration rates • Large islands have lower extinction rates

43. The species-area curve • Large islands contain more species than small islands • They are easier to find and have lower extinction rates • They possess more habitats

44. Small “islands” of forest rapidly lose species • Forests are fragmented by roads and logging • Small forest fragments lose diversity fastest • Starting with large species • Fragmentation is one of the prime threats to biodiversity

45. Should conservation focus on endangered species? • Endangered Species Act (1973) (ESA) = forbids the government and private citizens from taking actions that destroy endangered species or their habitats • To prevent extinction • Stabilize declining populations • Enable populations to recover • As of 2007, the U.S. had 1,312 species listed as endangered or threatened

46. Despite opposition, the ESA has had successes • Peregrine falcons, brown pelicans, bald eagles, and others have recovered and are no longer listed • Intensive management has stabilized other species • The red-cockaded woodpecker • 40% of declining populations are now stable • These successes occur despite underfunding of the U.S. Fish and Wildlife Service and the National Marine Fisheries Service • In recent years, political forces have attempted to weaken the ESA

47. The ESA is controversial Many Americans support protection of endangered species Opponents feel that the ESA values endangered organisms more than the livelihood of people Private land use will be restricted if an endangered species is present “Shoot, shovel, and shut up” = landowners conceal the presence of endangered species on their land But, the ESA has stopped few development projects Habitat conservation plans and safe harbor agreements = landowners can harm species if they improve habitat for the species in other places

48. Other countries have their own version of the ESA • Species at Risk Act (2002) = Canada’s endangered species law • Stresses cooperation between landowners and provincial governments • Criticized as being too weak • Other nations’ laws are not enforced • The Wildlife Conservation Society has to help pay for Russians to enforce their own anti-poaching laws

49. Protecting biodiversity Captive breeding – individuals are bred and raised with the intent of reintroducing them into the wild Zoos and botanical gardens Some reintroductions are controversial Ranchers opposed the reintroduction of wolves to Yellowstone National Park Some habitat is so fragmented, a species cannot survive

50. Protecting biodiversity • Cloning – a technique to create more individuals and save species from extinction • Most biologists agree that these efforts are not adequate to recreate the lost biodiversity • Ample habitat and protection in the wild are needed to save species