1. I. I.Biodiversity – Factors E. E.Exotic Species Species invasions may profoundly affect ecosystems Detrimental exotic species usually are Superior competitors Ex – Argentine ants, starlings, zebra mussels Effective predators Ex – Nile perch, mongeese

2. I. I.Biodiversity – Factors E. E.Exotic Species 1. 1.Zebra mussel Competitor in Great Lakes and elsewhere Transported from Europe in ballast water Fouling organism Restricts movement of water through intake pipes Colonizes boat hulls, pier pilings, buoys, etc. Fouls other organisms (clams, mussels) Filter feeder – removes larvae and particulate material Outcompetes native shellfish species for food and space Removes larvae from water

4. I. I.Biodiversity – Factors E. E.Exotic Species 2. 2.Mongoose Predator in Hawaii Introduced in 1883 to combat rat population Prey on native birds 3. 3.Lionfish Venomous predator Introduced in Caribbean/W Atlantic ca. early/mid 1990’s Preys on 65+ spp. of fishes No natural predators

5. Nile perch – Lake VictoriaBrown tree snake - Guam Argentine ants - CaliforniaCaulerpa taxifolia - California

6. II. II.Biodiversity – Value A. A.Value to Humans Economic Ex – Lomborg: $3-33 trillion annually Biodiversity loss could lead to removal of species that benefit humans but aren’t currently known to do so 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 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 (charisma?) Ex – Economic value of viral resistance added to commercial strains of perennial corn through hybridization with teosinte (Mexican wild grass) is ~ $230-300 million Ex – Weedy tomatoes from Peru Discovered in 1962 during search for potatoes Seeds sent to researcher at UC Davis who used plants to breed with other tomatoes In 1980 after nearly 10 generations of crossing and backcrossing, new strains were produced with larger fruit, improved pigmentation and increased concentrations of sugars and soluble solids

7. II. II.Biodiversity – Value B. B.Ecosystem Value Biodiversity can have large effects on ecosystem stability and productivity 1. 1.Benefits of biodiversity a. a.Productivity Halving species richness reduces productivity by 10-20% (Tilman) Average plot with one plant species is less than half as productive as a plot with 24-32 species Question – Can these results be extrapolated to other systems and time/space scales? 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?

8. II. II.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 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 maintained more biomass during drought than lower diversity (fertilized) plots High diversity may confer greater resistance to pests and diseases Ex – Higher diversity plots of native plant species had greater resistance to fungal diseases, reduced predation by herbivorous insects and reduced invasion by weeds

9. II. II.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 Charismatic megafauna: What about non-charismatic 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 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

10. III. III.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

11. IV. IV.Genetic Engineering A. A.Background Concept based on idea that organisms share same basic genetic material (DNA) Functionally similar units (genes) Same basic mechanisms of gene expression Theoretically possible to transfer genes between organisms and expect traits to be transferred faithfully Insertion of a foreign gene into a species’ genome creates a transgenic organism Inserted gene may or may not be expressed Theoretically, no limits on what can be inserted Ex – Insulin gene inserted into bacteria Ex – UCSD researchers inserted bacterial luciferin/luciferase genes into tobacco plant Technology offers potential to create novel organisms with unusual and potentially beneficial attributes

13. IV. IV.Genetic Engineering A. A.Background Concept based on idea that organisms share same basic genetic material (DNA) Functionally similar units (genes) Same basic mechanisms of gene expression Theoretically possible to transfer genes between organisms and expect traits to be transferred faithfully Insertion of a foreign gene into a species’ genome creates a transgenic organism Inserted gene may or may not be expressed Theoretically, no limits on what can be inserted Ex – Insulin gene inserted into bacteria Ex – UCSD researchers inserted bacterial luciferin/luciferase genes into tobacco plant Technology offers potential to create novel organisms with unusual and potentially beneficial attributes

14. IV. IV.Genetic Engineering B. B.Purposes 1. 1.Accelerate and refine selection process “Normal” hybridizing limited by Generation time Combining entire genomes, not just traits of interest 2. 2.Create otherwise unattainable hybrids Ex – Arctic flounder and strawberry or tomato Bottom line - Genetic engineering of organisms is intended to benefit humans, not modified organisms Proponents stress potential benefits to humankind and the environment Opponents emphasize potential risks and concerns Conversation with Hugh Grant