1. I. I.Biodiversity – Definitions and Assessment Major issue – Potential loss as a result of human activities A. A.Definitions Discussion requires clear consensus about what biodiversity is and how it’s defined Fundamental unit = species What is a species?? 1. 1.Species Group of genetically similar organisms that interbreed naturally and freely to produce viable, fertile offspring, but do not share this behavior and outcome with individuals of other species Problem: Many people consider this definition to be inadequate. Why??

2. I. I.Biodiversity – Definitions and Assessment A. A.Definitions 1. 1.Species a. a.Asexual Reproduction/Parthenogenesis All prokaryotes Some protists, fungi, plants, animals b. b.Interbreeding Naturally & Freely Some isolated populations could interbreed if geographic barrier could be surmounted Separate species? Subspecies? Populations? c. c.Natural Hybrids Ex – Horse + Donkey  Mule Ex – Queen + Blue  Townsend’s Angelfish Separate species? If a natural hybrid disappears, is it really gone so long as parent species remain? d. d.Polymorphism Ex - Hamlets How different must two species be to constitute separate species? Humans and chimpanzees are estimated to be 98% identical at the DNA level.

4. I. I.Biodiversity – Definitions and Assessment A. A.Definitions 1. 1.Species a. a.Asexual Reproduction/Parthenogenesis All prokaryotes Some protists, fungi, plants, animals b. b.Interbreeding Naturally & Freely Some isolated populations could interbreed if geographic barrier could be surmounted Separate species? Subspecies? Populations? c. c.Natural Hybrids Ex – Horse + Donkey  Mule Ex – Queen + Blue  Townsend’s Angelfish Separate species? If a natural hybrid disappears, is it really gone so long as parent species remain? d. d.Polymorphism Ex - Hamlets How different must two species be to constitute separate species? Humans and chimpanzees are estimated to be 98% identical at the DNA level.

5. BlueQueen Townsend’s

6. I. I.Biodiversity – Definitions and Assessment A. A.Definitions 1. 1.Species a. a.Asexual Reproduction/Parthenogenesis All prokaryotes Some protists, fungi, plants, animals b. b.Geographic Isolation Populations could interbreed if geographic barrier could be surmounted Separate species? Subspecies? Populations? c. c.Natural Hybrids Ex – Horse + Donkey  Mule Ex – Queen + Blue  Townsend’s Angelfish Separate species? If a natural hybrid disappears, is it really gone so long as parent species remain? Quagga d. d.Polymorphism Ex - Hamlets How different must two species be to constitute separate species? Humans and chimpanzees are estimated to be 98% identical at the DNA level.

7. BarredBlack Blue Golden Indigo Yellowtail

8. I. I.Biodiversity – Definitions and Assessment A. A.Definitions How do we identify a species? How do we quantify the number of species in an area when there is disagreement about what constitutes a species? Recently: Focus on preservation of processes that lead to speciation What processes produce and maintain species? 2. 2.Reproductive Isolation Many factors can prevent individuals from interbreeding Prezygotic Act prior to fertilization Postzygotic Act following fertilization

9. Time of Day Time of Year Courtship Sounds/Songs Flowers Fiddler Crabs Plants Broadcast Spawners Bullfrog x Leopard Frog Horse (2n=64) x Donkey (2n=62)  Mule (2n=63)

10. I. I.Biodiversity – Definitions and Assessment A. A.Definitions 3. 3.Components of Biodiversity The term “biodiversity” often is used incorrectly or incompletely Not synonymous with “species diversity” Encompasses three measures a. a.Species Diversity 1) 1)Species richness – Total number of species Often cited incorrectly as “biodiversity” Fairly simple to estimate from rarefaction curves 2) 2)Evenness – Proportions of species in a community More difficult to determine (requires more complete survey) b. b.Genetic Diversity – Variety of genotypes c. c.Ecosystem Diversity – Variety of habitat types

12. I. I.Biodiversity – Definitions and Assessment A. A.Definitions 3. 3.Components of Biodiversity The term “biodiversity” often is used incorrectly or incompletely Not synonymous with “species diversity” Encompasses three measures a. a.Species Diversity 1) 1)Species richness – Total number of species Often cited incorrectly as “biodiversity” Fairly simple to estimate from rarefaction curves 2) 2)Evenness – Proportions of species in a community More difficult to determine (requires more complete survey) b. b.Genetic Diversity – Variety of genotypes c. c.Ecosystem Diversity – Variety of habitat types

13. I. I.Biodiversity – Definitions and Assessment B. B.Estimates of Biodiversity Described species ~ 1.8 million Insects > 1,000,000 species Plants > 290,000 species Probably an underestimate Only ~5000 species of bacteria Less conspicuous species studied less often Estimates range from 5 – 30 million Average estimate ~ 17.5 million C. C.Estimates of Extinction Rates Current estimates ~ 17,500 species year -1 1 out of every 1000 species on Earth each year “Background” rate from fossil record 1 out of every 1-10 million species on Earth each year

14. I. I.Biodiversity – Definitions and Assessment C. C.Estimates of Extinction Rates Problems a. a.Difficult to know when a species is extinct Ex – Coelacanth, ivory billed woodpecker, giant lemur b. b.Extinctions may not happen immediately Short-lived species show effects rapidly Long-lived species may appear to be unaffected for long periods of time “Biologically extinct” – Populations not self- sustaining “Living dead” - Janzen c. c.Uncertainty about number of species in an area Wilson – “No precise estimate can be made of the numbers of species being extinguished in the rain forests or in other major habitats, for the simple reason that we do not know the numbers of species originally present”

15. I. I.Biodiversity – Definitions and Assessment C. C.Estimates of Extinction Rates Consideration: Wilson – Projections in tropical settings (where most of biodiversity loss currently is happening) are conservative Tropical species have localized distributions that make them especially vulnerable to habitat loss Damaging loss of genetic diversity may occur, even if outright extinction of a species doesn’t happen

16. II. II.Biodiversity – Factors A. A.Selective Mortality Species-specific diseases/pests Ex – Dutch elm disease Ex – Western bark beetles Predation Ex – Birds with colorful plumage Ex – Sea urchins (sushi)

17. II. II.Biodiversity – Factors B. B.Habitat Disturbance Non-selective habitat disturbance has potential to increase diversity Prevents competitive exclusion Intermediate disturbance  Maximum diversity

18. II. II.Biodiversity – Factors B. B.Habitat Disturbance Fire and fire-dependent species Ex – Peter’s Mountain Mallow (Iliamna corei) Discovered in 1927 (50 plants) Endemic to meadow in western Virginia 1986 - Three plants remaining Not setting seed Listed as endangered Research on seeds indicated importance of fire Cracks hard seed coat, aiding germination Removes competing vegetation Had been suppressed in the area Controlled burns in 1992 and 1993 led to appearance of 500+ seedlings

19. II. II.Biodiversity – Factors C. C.Habitat Fragmentation/Destruction Most significant factor causing species loss Smaller habitats support fewer species and smaller populations than large habitats Population sizes tend to fluctuate more in smaller habitats than large habitats Reduced population  Lower genetic diversity Behavior of territorial species changes in fragments, esp. when territory size ~ fragment size Fragments may not support self-sustaining populations (rely on immigration from outside)

20. Mount Hood National Forest, Oregon Patches due to timber removal

21. II. II.Biodiversity – Factors C. C.Habitat Fragmentation/Destruction Most significant factor causing species loss Smaller habitats support fewer species and smaller populations than large habitats Population sizes tend to fluctuate more in smaller habitats than large habitats Reduced population  Lower genetic diversity Behavior of territorial species changes in fragments, esp. when territory size ~ fragment size Fragments may not support self-sustaining populations (rely on immigration from outside)

22. II. II.Biodiversity – Factors C. C.Habitat Fragmentation/Destruction Fragmentation increases edge effects Positive effects Increased light to plant species at edges Negative effects Increased predation by animals foraging at habitat edge Ex – Nesting success among migratory birds in Midwestern forests was lower in fragments due to increased nest predation and parasitism by cowbirds Benefit – Herbivorous insects in fragmented habitats experience less parasitism (reduction of parasite’s habitat)

23. III. III.Biodiversity – Value A. A.Value to Humans Biodiversity loss could lead to removal of species that benefit humans but aren’t cultivated currently Ex – Chapin et al. suggested increase in frequency of Lyme disease during 20 th century may have been related to increase in abundance of tick-bearing mice (once controlled by food competition with passenger pigeons) Species extinction reduces potential pool of species containing chemical compounds with pharmaceutical or industrial applications Counter – Many pharmaceutical companies now use directed design to search for new drugs Question – How do we know whether a species has value? Problem – Benefits may not be obvious Difficult to convince people that it’s important to preserve something with no immediately apparent intrinsic value to them Ex – Economic value of viral resistance added to commercial strains of perennial corn through hybridization with teosinte (Mexican wild grass) is ~ $230-300 million/year

24. III. III.Biodiversity – Value B. B.Ecosystem Value Biodiversity can have large effects on ecosystem productivity and stability 1. 1.Benefits of biodiversity a. a.Productivity Halving species richness reduces productivity by 10-20% (Tilman) b. b.Nutrient retention Loss of nutrients through leaching is reduced when diversity is high Caveat – Studies to date have focused on low diversity communities (Why?); can those results be generalized?

25. III. III.Biodiversity – Value B. B.Ecosystem Value 1. 1.Benefits of biodiversity c. c.Ecosystem stability Mechanism Multiple species within a trophic level compete for resources If the abundance of one species declines due to perturbation, competing species may increase in abundance Individual species abundances may vary, but community as a whole is more stable with more species Consequences High diversity doesn’t guarantee that individual populations won’t fluctuate Ex – Higher diversity (unfertilized) plots of native plant species 1) 1)Maintained more biomass during drought than lower diversity (fertilized) plots 2) 2)Conferred greater resistance to pests and diseases 3) 3)Showed reduced predation by herbivorous insects and reduced invasion by weeds

26. III. III.Biodiversity – Value B. B.Ecosystem Value 2. 2.Considerations a. a.Species richness vs. Species evenness Simple species richness may be deceptive as an indicator of biodiversity and ecosystem stability Evenness usually responds more rapidly to perturbation than richness and may have important ecosystem consequences Richness is typical focus of studies and policy decisions b. b.Importance of individual species Different species affect ecosystems in different ways (keystone species vs. non-keystone species) Ex – Sea otters/Sea urchins/Kelp forests in eastern Pacific Ocean Ex – Pack ice/Krill/Salps in Southern Ocean Question - How many species are required to maintain “normal” ecosystem function and stability? No magic number Losing one ant species in a tropical forest may have less immediate impact than losing one species of fungus that is crucial to nutrient cycling in the soil

27. IV. IV.Biodiversity – Management Strategies outlined in Convention on Biological Diversity Developed between 1988 and 1992 Opened for ratification at UN Conference on Environment and Development (Rio “Earth Summit”) Ratified by 168 nations; went into force in Dec 1992 Objectives – “…the conservation of biological diversity, the sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources…” Articles 8-9 specify a combination of in situ and ex situ conservation measures Primary use of in situ conservation Use of ex situ measures as a complement