Biodiversity Value

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• Biodiversity Value
• Value to Humans
• Biodiversity loss could lead to removal of
  species that benefit humans but arent cultivated
  currently
• 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
• Ex Economic value of viral resistance added to
  commercial strains of perennial corn through
  hybridization with teosinte (Mexican wild grass)
  is 230-300 million
• Question How do we know whether a species has
  value?
• 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 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 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

4

• 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
• 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

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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 most 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 UCSD researchers inserted bacterial
  luciferin/luciferase genes into tobacco plant
• Ex Insulin gene inserted into bacteria
• 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
• 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

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• Genetic Engineering
• Advantages
• Greater agricultural yields
• More food production per acre could
• Reduce area needed to support existing population
• Support future population growth
• Ex European corn borer destroys 7 of annual
  corn harvest worldwide
• Modified corn resistant to ECB could eliminate
  this loss
• Extra corn 7-10 mmt (enough to feed 60 million
  people)
• Reduced herbicide use
• Wheat, corn, soybeans, cotton engineered to be
  resistant to certain herbicides (e.g. Roundup)
• Farmers can spray crops with less herbicide to
  kill weeds
• Ex Soybeans Reduction of pesticide use by
  10-40 from 1996-1997
• Reduced pesticide use
• Crop plants can be engineered for resistance to
  certain pesticides
• Ex Insect resistant cotton planted in Alabama
  led to an 80 reduction in use of insecticides on
  cotton from 1996-1997
• Environmentally beneficial tasks
• Ex Bacteria engineered to degrade petroleum
  rapidly used to clean up oil spills

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• Genetic Engineering
• Drawbacks
• Opponents emphasize failures of technology,
  potential environmental harm
• Frankenfood
• Farmageddon
• Harm to native species through competition
• Transgenic organisms could be superior
  competitors
• Potential route to extinction for native species
• Damage to beneficial insects
• Ex - Some evidence that ladybugs and lacewings
  suffer (shorter lifespan, reduced reproduction)
  when fed aphids and caterpillars that had fed on
  GM potatoes and corn, respectively
• Damage to soil community
• Certain GM crops could reduce activity of soil
  fungi and microbes
• Negative impact on nutrient cycling in the soil
• Release of resistance genes
• Could potentially lead to super weeds if
  resistance genes get transferred to weedy species
• Could damage natural communities and exacerbate
  weed control problems
• Upset natural balance of ecosystems
• Could result from release of GMOs or
  hybridization between GMOs and native species