Lecture 23 Notes

1. Biodiversity 2
a. Global Status and Threats, Conservation Strategies
b. Part of last lecture on valuation will not be covered

2. Past extinctions
a. Extinction is natural part of life
b. History of life - five mass extinctions - boundaries between ecological epics
c. Causes of mass extinctions are diverse - meteors, continental movement, climate changes, temperature changes
d. Diversity of life has increased over time, recovers after mass extinctions
e. Lots of extinctions involve evolutions into something else
f. Sixth extinction -unique in rapidity, that humans are involved
i. Phase 1 - began with spread of humans 100,000 years ago
ii. Phase 2 - began 10,000 years ago with dawn of agriculture - assured food supply, division of labor, rise of civilization and increase in human population
iii. Phase 3 - began 250 years ago with industrial and scientific revolutions - raised carrying capacity - more human capacity to dominate the earth

3. Where humans have colonized new areas, associated with decline of large animals
a. Declines in biodiversity associated with human populations
b. Graph shows large animal populations falling with colonization by humans of different continents, islands - australia, North America, New Zealand

4. North American extinction
a. Science article
b. Extinction of large animals previously attributed to climate change
c. Hypothesis in 1970s - advance of human hunters when Bering land bridge existed into North America - colonists were advanced hunters, wiped out large animals
d. About ten years ago, third idea discussed - glaciers retreated, animals more available to hunters, upset of ecological balance
e. Paper from two weeks ago - dung survey - new data set shows decline in biomass began 15,000 years ago (before humans arrived across land bridge) - earlier human population reduced population of large herbivores, changed vegetation, arrival of hunters via land bridge wiped out large herbivores

5. Threats to biodiversity
a. Sextet of threats: over-exploitation, exotic species, habitat destruction, climate change, pollution, domino effects

6. IUCN rankings
a. International Union of Conservation of Nature
b. Critically endangered, endangered, vulnerable - classifications

7. Over-Exploitation
a. Has caused a number of extinctions, often large and spectacular species

8. Over-Exploitation
a. Over-fishing of cod
b. Single largest threat to fishes in the oceans is over-harvesting
c. Not only threat, but one of most serious

9. Bushmeat trade
a. "emptying of forest"
b. Where people have access to wildlands, over-harvesting of bushmeat significant problem - e.g. Africa
c. Development of natural resources (e.g. oil) involves development of infrastructure, provides access to wildlands, diminished game populations
d. Significant cause of extinctions

10. Non-indigenous species
a. Other names - alien species, exotic species
b. Invasive, nuisance used for species that have strong negative impact
c. What makes it a good/bad invader - utility to humans, ecosystem impact
d. Asian carp - introduced in southern US, spread into Mississippi river, electric fence put in place to keep carp out of Lake Michigan, poisoned Chicago river to kill fish that got past fence

11. Zebra mussel case history
a. Exotic species that came from europe, became established in Great Lakes, went down Mississippi River
b. Continue to spread, have had enormous effect on both the Hudson River and the Great Lakes
c. Have shunted energy to different zone
12. In Hudson River, zebra mussels affect phytoplankton, which has cascade effect
a. Impact - have removed algae and sediments, improved clarity of water,

13. Zebra mussel case history
a. Graph shows change in different parts of ecosystem

14. Nile Perch in Lake Victoria
a. Native to Nile river, but not to African Great Lakes
b. Introduced to lakes by biologists
c. Great number of fish unique to the lakes
d. Will likely cause hundreds of species in Lake Victoria to go extinct
e. Huge export of Nile Perch, very successful fishery - enormous economic impact, social impact

15. Michigan invaders
a. Sea lamp ray, time of arrival in lakes, effect on lake trout
b. Gypsy moth

16. Causes of Spread of Aquatic NIS
a. Colonial nostalgia - acclimation societies in NZ - 20 of 46 species of fishes found in NZ are exotic - people import fish from where they come from
b. Fish culture escapees
c. Pet trade - people throw pet fish into ponds
d. Inter-basin transfers
e. biocontrol

17. What influences invasion success?
a. Aspects of invader - trophic category, behavior, physiology, life history traits
b. Aspects of receiving environment - habitat matching to some degree, habitat resistance (fullness of niches)
c. Success rates appear to be high - ~50%+ of invasive species successful

18. California case study
a. 68 native species, 110 documented non-native introductions, 43% failed
b. Best predictors of success
i. Past history of successful invasions (4 times as likely to be successful)
ii. Broad environmental tolerance
iii. Likes trashed environments
iv. Similar source and recipient environments
v. At least 100 individuals, multiple releases, or both

19. Chart
a. Think of establishment of invasive species as number of stages
b. Transport, living, inoculation, establishment, spread
c. Wise to keep invaders to very small number to make chain as unlikely as possible

20. NIS superstars
a. Some species seem to be good invaders: tilapia, common carp
b. Why are they so successful? Can't answer that well today

21. Habitat loss and fragmentation
a. Chart - loss of atlantic forest habitat in Brazil; remaining habitats small and disconnected
b. Habitat fragments too small to maintain viable populations, too fragmented to allow rescue effect

26. Climate change
a. Graphic shows how summer climate of midwest states will change from today to 2095 - future climate will be very different from modern climate
b. Michigan will no longer be suitable for many species that currently live here

27. Global Warming
a. Chart shows distribution of bird today and likely distribution at point when CO2 levels double
b. Bird distribution moves north
c. For many species, there may not be a big impact
d. Unknown how adaptable many species are to climate change - unknown effects on communities if species begin moving with climate change - could bring significant interaction effects
e. Graph of landscape from hundreds of years ago - species found everywhere north of southern range limit; later, with human impacts, reserve put in place; later, with climate change, reserve no longer serves population well
f. In future we'll still have Yellowstone, but how many species that we value there will still be able to live there?

28. Domino Effects
a. As soon as one species go extinct, all species that depend on it go extinct
b. Not a lot of evidence for domino effect
c. Black footed ferret, preys on prairie dogs
d. Prairie dog colonies declining, black footed ferret has become rare

29. Extinction rates
a. Bob May - "Species are now perishing at 1000 times or even 10000 times the background extinction over the past 600 million years"
b. Background extinction - historic rate
c. Mass extinction - five great extinctions
d. Anthropogenic extinctions - human caused
e. How can we know probable rate?
i. Estimate probable number of species
ii. Estimate rate of habitat loss (know rate of deforestation)
iii. Use species-area relationship to estimate species loss
f. If we lose 1% of forest per year, can expect half of forest to disappear in 70 years

30. Historical vs present-day extinctions
a. Rate of loss of species from fossil record
b. Current rate
c. Future rate

31. Graphs
a. Bigger areas have more species
b. Slope = 0.2 to 0.3
c. Island that is ten times bigger has about twice as many species

32. Graph
a. Islands from largest to smallest
b. Larger number of species on larger islands

33. Estimating rates of species loss
a. For mainland, slope is 0.1 to 0.2
b. Use relationship between area of habitat and number of species
c. Resulting loss rate of species results in loss of 25%-50% of world's species by 2100

34. Take-home messages
a. Biodiversity threatened by six factors
b. Habitat loss represents single biggest threat
c. Over-harvest important in oceans and for bushmeat animals
d. Some 25-50% of world's biodiversity likely to be lost in 21st century

35. Protecting biodiversity

36. How can we protect biodiversity
a. Protected lands - what is current extent? How does level vary among protected lands?
b. Protected lands today cover ~12% of earth's land area; must have good management for remaining non-protected lands

37. IUCN Protected Area Categories
a. Wide range of protected area categories
b. In state of Michigan, 21% of land has some sort of protected status
c. About 20% is very active multiple use; may not be that much biodiversity protection going on
d. Simply saying that something is protected does tell you much about what is going on

38. Protected areas can be very effective
a. 0.2% of costa rica's land area contains large number of species

39. Protected areas in Africa

40. New Protected Areas
a. Various organization have numeric goals
b. Land surface protected must be distributed across different biosystem types
c. Identification of gaps in networks of protected lands to determine where new protected areas should be located
d. Size, shape, linkages, matrix - how big does it need to be to accomplish goal?

47. Graph
a. Number of individuals vs area
b. Larger area has more individuals
c. Large carnivores need area larger than 3 units; need minimum area to support different classes of animals
d. Second graph - each dot is a different park in US; x-axis is area; y-axis is number of extinctions since park established
i. knowing ecology of habitat, calculated number of species that would have been there prior to human impact, compared to number of species in park now
ii. Small parks have more extinctions than large parks
e. Size of reserve very important

53. Take-away messages

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