Biodiversity Defined

1. Biodiversity Defined • “Biodiversity is the total variety of life on earth. It includes all genes, species and ecosystems and the ecological processes of which they are a part” (Convention on Biodiversity, 1992)

2. 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

3. Where is the biodiversity? • Endemic species – restricted to a small region • isolated areas (islands, mountain ranges) • product of unique habitat, climate features

4. Biodiversity hotspots - areas with a high concentration of endemic species, experiencing rapid habitat loss

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

9. Genetic diversity • Encompasses the differences in DNA among individuals within species and populations • The raw material for adaptation to local conditions

10. Genetic diversity • 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

11. 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

12. 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

13. Insects outnumber all other species

14. 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

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. Current Status of Biodiversity • 1.4 million described species, possibly 10 million in total • Background extinction rate – rate of species loss in the absence of human activities • fossil record: species survive 1-10 million years • one year: one species has a 1 in 1-10 million chance of going extinct • total: 1 extinction per year

19. 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

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

21. 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

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

24. Ecological interactions • Biodiversity is more than the sum of the parts • Interactions “structure” communities, maintain diversity, and make ecosystems work • e.g. Competition • Predation • Mutualisms (e.g. pollination, seed dispersal)

25. Some estimates for current rate: • 1 species per hour • 1 million species total, so far • 10% of all species so far • 8.8% of all species • 27,000 species per year • 20% of neotropical plant species • 100 to 10,000 times the background rate

26. Numbers of threatened/endangered species: • 5,188 vertebrates (9%) • 1,992 invertebrates (0.17%) • 8,321 plants (2.89%) • 2 lichens (0.02%) • Since 1600, ~1000 species have gone extinct (probably many more)

27. Why do species go extinct? 2 separate processes: • Something causes a large population to decline. • Small populations go extinct.

28. Causes of species declines • Habitat destruction and fragmentation • Introduced species • Exploitation and overharvesting • Pollution • Climate change

29. Conservation biology • Concerned with loss of biodiversity, not just loss of species • “Fundamental loss of resources in genetics, species, community attributes and ecosystemproperties” • Flip side: maintenance of biodiversity, ecological and evolutionary processes

30. Why care about biodiversity? • Intrinsic value (Muir, 1838-1914) • All species have value independently of their utility to humans • Utilitarian value (Pinchot, 1865-1946) • Species that provide the “greatest good to the greatest number” (over the longest time) have value • Cons Bio : (Leopold, 1886-1948) • can include both value systems • “To keep every cog and wheel is the first precaution of intelligent tinkering" (Leopold 1943).

31. Aldo Leopold (1886-1948)Evolutionary-Ecological Land Ethic Biological communities: assemblages of interdependent species Maintaining the health of natural ecosystems and ecological / evolutionary processes Humans exist within the ecological community; depend on ecosystem services Synthetic approach: Both intrinsic value and utilitarian value

32. Why be concerned about biodiversity loss if extinction is a fact of life? Is extinction outpacing speciation potential? Moderate certainty: current extinction rates > by 100 – 1000 times 10 – 30 % of mammals, birds and amphibians threatened

33. From Wilcove 1996 Major drivers of endangerment What’s missing?

34. Threats to terrestrial species • Terrestrial habitat loss • 39-50% of land surface transformation

35. 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

36. Result of habitat loss • Reduction in total area  decrease in size, # of populations  local extinctionsfewer species • Reduction in habitat diversity • Reduced species diversity • Cascading effects, co-extinctions

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

38. The forested areas of Warwickshire, England From Primack 2002 Habitat fragmentation • Above and beyond habitat loss • Isolation: reduced immigration, re-colonization • Edge effects

39. Invasion The distribution of species on Earth is becoming more homogenous The rate of invasion is increasing over time HOMOGENIZATION Growth in Number of Marine Species Introductions in North America and Europe

40. Introduced cheatgrass, Bromus tectorum, has transformed the Great Basin shrub-steppe ecosystem • Has increased fire frequency from once/80 years to once/4 years! • Occupies over 5 million hectares of Great Basin

41. 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

42. Climate change effects on biodiversity • Range shifts • Latitudinal range • Altitudinal range • Mis-matched interactions • Reassembled (scrambled) communities • Feedbacks (e.g. vegetation and climate) • Species Endangerment

43. 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

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

45. Climate change endangers polar bears • Sea ice is the key • Bottom up: habitat for micro-algae • Top down: seal hunting ground; corridors to dens • Loss of sea ice  endangers polar bear • Loss of top predator: cascading effects on Arctic food web

46. Climate change can induce coral reef bleaching http://www.ogp.noaa.gov/misc/coral/98bleaching/ Bleached and normally pigmented Pocillopora colonies

47. Oceans and Freshwater Aquatic habitats • If anything are more vulnerable to same threats, with enhanced vulnerability to over-exploitation and pollution • Freshwater • USA: Very high endangerment levels in fish & amphibians (25-40%) and crayfish & molluscs (> 60%) compared to terrestrial vertebrates (15-18%

48. Botsford 1997 Over-exploitation of global ocean fisheries • > 60% of the world’s fisheries are fully to over exploited, or depleted • By-catch increases fish-catch by 30%

49. Conserving biodiversity • Genetic level: seed, egg, sperm banks • Population and species level – science of managing small populations • Captive breeding (zoos/botanical gardens) • Reintroductions • Population management in the wild • Protection (hunting, disease, habitat) • Genetic management (translocations) • Habitat restoration

50. Conserving biodiversity: habitat, species, ecosystem level • Protected areas • Managing the matrix • Restoration • Wildlife-friendly agriculture