Biodiversity

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• Biodiversity Factors
• 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

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• Biodiversity Factors
• Exotic Species
• 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

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

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Nile perch Lake Victoria
Brown tree snake - Guam
Argentine ants - California
Caulerpa taxifolia - California
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• Biodiversity Value
• Value to Humans
• Economic
• Ex Lomborg 3-33 trillion annually
• Biodiversity loss could lead to removal of
  species that benefit humans but arent currently
  known to do so
• Ex Chapin et al. suggested increase in
  frequency of Lyme disease during 20th 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 its 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

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• Biodiversity Value
• Ecosystem Value
• Biodiversity can have large effects on ecosystem
  stability and productivity
• Benefits of biodiversity
• 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?
• 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?

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• Biodiversity Value
• Ecosystem Value
• Benefits of biodiversity
• 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 doesnt guarantee that individual
  populations wont 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

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• Biodiversity Value
• Ecosystem Value
• Considerations
• 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
• 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

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• 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

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• Genetic Engineering
• 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

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• Genetic Engineering
• 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

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• Genetic Engineering
• Purposes
• Accelerate and refine selection process
• Normal hybridizing limited by
• Generation time
• Combining entire genomes, not just traits of
  interest
• 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