Threats to Biodiversity chap 3

1. Threats to Biodiversitychap 3 “Extinction is the most irreversible and tragic of all environmental calamities. With each plant and animal species that disappears, a precious part of creation is callously erased” Michael Soule, 2004

2. Threats to Biodiversity • As our numbers climb, we expand agricultural conversion, import invasive species, hunt more species, degradate habitat, fragment and lose habitat, pollute water and air, impact climate… • In short, we are causing the 6th mass extinction, the only biological driven one

3. Threats to Biodiversity • Major factors impacting biodiversity

4. Threats to Biodiversity • Habitat Degradation • Includes conversion from suitable to unsuitable, lowering quality, fragmentation that lower PVA • Causes: many industries (e.g. forestry, agriculture, development, fishing, mining, chemical)

5. Threats to Biodiversity • Overexploitation • Hunting, collecting, fishing (and indirect by-catch), trade of animals (and parts)

6. Threats to Biodiversity • Invasive Species • With our help, species have the ability to get virtually anywhere in the world • Direct actions: predation, parasitism, disease, competition or hybridization • Indirect paths: changing abundances, disruption of mutualisms, modifying habitat, reducing habitat quality)

7. Threats to Biodiversity • Anthropogenic Climate Change • Climate has been a cause of previous mass extinctions • Couple this with lower abundance, invasive species and other problems, a severe impact is likely from climate change • Climate change will also trigger additional biological responses (e.g. malaria in temperate places)…Fig 3.3

8. Threats to Biodiversity • “Snowballing” effect of the invasion of the alien root pathogen

9. Threats to Biodiversity • “Snowballing” effect of the invasion of the alien root pathogen • Indirect effects

10. Threats to Biodiversity • Anthropogenic Pollution • There are direct discharges of chemicals into the environment, there are also pollutants released into the atmosphere • Toxic chemicals (e.g. mercury, lead) are found even in remote areas • Also have the problem of bioaccumulation (or biomagnification)

11. Threats to Biodiversity • Toxic chemicals (PCB’s and dioxins) accumulate in fatty tissues

12. Anthropogenic Extinctions… impact on communities and ecosystems • Loss of species, populations and/or habitat is dramatic and extreme • Extinction as a process… • Can be local or global (also, ecological)

13. Anthropogenic Extinctions… impact on communities and ecosystems • Early extinctions probably caused by overexploitation • Now, habitat degradation and/or invasive species major factors

14. Anthropogenic Extinctions… impact on communities and ecosystems • No. of genera (megamammal) extinct and cause • 72% Aust • 88% NAm

15. Anthropogenic Extinctions… impact on communities and ecosystems • Consider Polynesian colonization of Pacific Islands 1-3KYA • Over 2000 species of birds (flightless rails) and 8000 populations driven to extinction • Story is not so simple… • Where invasive sp and habitat degradation combined, extinction followed

16. Anthropogenic Extinctions… impact on communities and ecosystems

17. Anthropogenic Extinctions… impact on communities and ecosystems • Since 1500, >129 sp extinct • Habitat loss major cause • Invasive sp contributed for many • Overexploitation for 1/5

18. Anthropogenic Extinctions… indirect impacts • Species don’t exist in a vacuum and extinctions usually have a ripple effect • ‘Cascade effects’ such as secondary extinctions may occur • E.g. plants with a single sp pollinator or seed dispersers • E.g. sea otters and sea urchins

19. Anthropogenic Extinctions… indirect impacts • Tambalacoque & Dodo

20. Anthropogenic Extinctions… indirect impacts • E.g. sea otters and sea urchins

21. Anthropogenic Extinctions… indirect impacts

22. Anthropogenic Extinctions… indirect impacts • Another problem is the removal of top predators, which may cause the ‘ecological release’ of mesopredators

23. Anthropogenic Extinctions… indirect impacts • So there are many important species in a given community and some are more important than others • Dominant sp: common, but also have strong effects on other members • Ecosystems engineers: those that modify the ecosystem (e.g. beaver, elephant) • Keystone sp: sp that has more impact on community than numbers (biomass) would suggest (e.g. bat pollinator)

24. Anthropogenic Extinctions… indirect impacts

25. Current Patterns of Global Endangerment • Best data on global endangerment are collated in the IUCN Red List of Threatened Species (www.redlist.org) • All species placed into one of 9 categories (3 primary categories: Critically Endangered, Endangered, Vulnerable) • To date, only 2.5% of species evaluated (and 41% considered endangered)

26. Current Pattern of Global Endangerment

27. Current Pattern of Global Endangerment

28. Current Pattern of Global Endangerment • What groups are in endangered? Turtles at 42%

29. Current Pattern of Global Endangerment • Globally threatened processes • Some dramatic phenomenon may disappear (e.g. large-scale migrations) • Read Essay 3.3

30. Current Pattern of Global Endangerment • Factors threatening biodiversity • Factors are listed in the Red List • Knowledge varies tremendously and by taxonomic group and habitat • Most face multiple threats and threats can act synergistically

31. Current Pattern of Global Endangerment • Overexploitation is major cause for fish

32. Current Pattern of Global Endangerment • Where are sp most at risk worldwide? • Not all biomes (and their inhabitants) are equally at risk • Most tropical habitats and grasslands have large substantial numbers of threatened vertebrates

33. Current Pattern of Global Endangerment

34. Current Pattern of Global Endangerment…the US • Geographically, there are very high numbers in SAm, SE Asia, sub-Saharan AF, Oceania, and NAm (where?) • The US is second (Ecuador) for the number of species though to be at risk of extinction globally (IUCN) • Many are plants (>5000sp), freshwater species (e.g. mussels {70%},crayfish, stoneflies)

35. Current Pattern of Global Endangerment…the US • Proportion of sp threatened in US

36. Current Pattern of Global Endangerment…the US • Examining threats to US sp A correlative cause of many of these factors is urbanization

37. Current Pattern of Global Endangerment • Threatened species in other countries • Unfortunately, many countries lack solid data on what and how many sp are actually in trouble • Some countries have a high proportion of the flora and fauna at risk • E.g. Madagascar 80% of plants and 30% of vertebrates (case study 3.2)

38. Current Pattern of Global Endangerment

39. Current Pattern of Global Endangerment • What types of sp are most vulnerable? • Through studies, we have determined there are ‘suites’ of characteristics that make some sp more vulnerable • E.g. large range requirements, narrow habitat range, rarity, low reproductive rate, extreme specialization or co-evolutionary dependancies

40. Current Pattern of Global Endangerment • Vulnerability due to Specialization • Many species (especially tropical) have narrow environmental ranges and highly specialized diets or habitats • Perturbations can easily disturb them • Specialization on other species can be precarious as well

41. Current Pattern of Global Endangerment • Top carnivores with low densities, large ranges, large body size, are often cited as being vulnerable to habitat degradation, as well as overexploitation • For marine animals, body size itself does not appear to be a problem, but is associated with another… low reproductive rate

42. Current Pattern of Global Endangerment • Vulnerability of Rare species • Why might a species be rare? • Consider 3 characteristics: geographic range, habitat breadth and abundance • How might each influence vulnerability? • How might they interact?

43. Current Pattern of Global Endangerment vent sp Island sp bats big cats raptors seabirds

44. Current Pattern of Global Endangerment • Let’s consider a case of extreme endemism: ‘Centinela Ridge’ in Ecuador • During a RAP inventory, 90 endemic plant species were discovered • Immediately following the inventory, entire ridge cleared for agriculture

45. Current Pattern of Global Endangerment • Island communities have relatively high rates of endemism, although communities maybe less rich than comparable mainland sites • However, many island biotas are frequently endangered; why?

46. Current Pattern of Global Endangerment • Case Study: birds of Channel Islands • 80 year comparison of pop(s) • 40% of small pop(s) went extinct (<10 bp) • 10% of pop(s) with 10-100 breeding pairs • 1 population of 100-1000 bp • No pop(s) if >1000 bp

47. Current Pattern of Global Endangerment • “Bad luck” species do not have intrinsically vulnerable traits, just bad luck • For example, many freshwater fish near large cities are vulnerable, whatever their LHC • 50% of variation in extinction risk for primates and carnivores is strictly due to anthropogenic distrubances

48. Current Pattern of Global Endangerment • Economic and Social Context • Economic growth and rising affluence drive habitat conversion and overexploitation • Unfortunately in the US, areas of high endemism and richness are areas of high human growth (e.g. s. CA, e-c TX, s FL)

49. Current Pattern of Global Endangerment • At the other end of the economic spectrum, billions live in poverty • 1B < $1/day • 2.7B < $2/day • As a result, unsustainable levels of burning, small-scale agriculture, grazing and bushmeat hunting occur wherever these practices help people survive

50. Current Pattern of Global Endangerment • Responses to the Biodiversity Crisis • Conservationists and developers agree where solutions need to come from: • 1) scientific analysis and promotion of the causes of biodiversity change • 2) technological improvements • 3) legal and institutional instruments • 4) economic incentives and plans • 5) social interventions