Biodiversity

1

• Biodiversity What is it?
• Definitions
• Contraction of biological diversity
• Fundamental unit species
• What is a species??
• A 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 Some people consider this definition to
  be inadequate. Why??
• Some natural interbreeding between species
• Not all species distinct and static hybrid
  swarms
• Some exchange of DNA without interbreeding
• Genetic polymorphism species flocks

2

• Biodiversity What is it?
• Definitions
• Components
• Term biodiversity often used incorrectly or
  incompletely
• Not synonymous with species diversity
• Encompasses three measures
• Species Diversity
• Species richness Total number of species
• Often cited incorrectly as biodiversity
• Evenness Proportions of species in a community
• More difficult to determine (requires more
  complete survey)
• Genetic Diversity Variety of genotypes
• Ecosystem Diversity Variety of habitat types

3
(No Transcript)
4

• Biodiversity What is it?
• Definitions
• Components
• Term biodiversity often used incorrectly or
  incompletely
• Not synonymous with species diversity
• Encompasses three measures
• Species Diversity
• Species richness Total number of species
• Often cited incorrectly as biodiversity
• Evenness Proportions of species in a community
• More difficult to determine (requires more
  complete survey)
• Genetic Diversity Variety of genotypes
• Keystone Species
• Ex Sea otters in kelp forests

5

• Biodiversity Estimation
• Estimates of Biodiversity
• Described species 1.8 million
• Insects gt 1,000,000 species
• Plants gt 290,000 species
• Probably an underestimate
• Only 11,000 species of bacteria
• Less conspicuous species studied less often
• Estimates range from 3 100 million
• Around 6200 new eukaryote species described each
  year
• Recent estimate 8.75 million (Mora et al. 2011)
• Still doesnt capture microbial diversity (could
  exceed all other diversity combined)
• Biases
• Splitting of taxa more common than lumping
• Tendency to increase number of described species
• Cryptic species

6

• Biodiversity Estimation
• Biodiversity Hotspots
• Myers Up to 20 of the worlds plant species
  and more than 20 of the animal species are
  confined to 0.5 of the land surface
• Biodiversity Hotspot Area with high degree of
• Biodiversity
• Endemism
• Risk of habitat degradation/loss
• Concept originally intended for tropical and
  subtropical areas
• Endemism less prevalent in temperate and polar
  regions

7

• 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. (2002) 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
• Problem Benefits may not be obvious
• Difficult to convince people that its important
  to preserve something with no immediately
  apparent 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

8

• 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)
• Nutrient retention
• Loss of nutrients through leaching is reduced
  when diversity is high
• Ecosystem stability
• Ex Higher diversity (unfertilized) plots of
  native plant species maintained more biomass
  during drought than lower diversity (fertilized)
  plots
• 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

• Biodiversity Value
• Ecosystem Value
• Considerations
• Species richness vs. 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

10

• Biodiversity Factors
• Nutrient Availability
• Oligotrophic
• Dominated by a few species able to survive on
  limited nutrients
• Low diversity, Low biomass
• Mesotrophic
• Support greater numbers of species
• Rapid colonizers held in check by nutrient
  limitation
• Less aggressive species capable of surviving
• High diversity, Medium biomass
• Eutrophic
• Dominated by a few species able to grow and/or
  colonize rapidly with abundant nutrients
• Low diversity, High biomass

11

• Biodiversity Factors
• Selective Mortality
• Predation
• Ex Birds with colorful plumage
• Ex Sea urchins (sushi)
• Species-specific diseases/pests
• Ex Dutch elm disease
• Ex Bark beetles

12

• Biodiversity Factors
• Habitat Disturbance
• Non-selective habitat disturbance has potential
  to increase diversity
• Prevents competitive exclusion
• Intermediate disturbance ? Maximum diversity

13

• Biodiversity Factors
• Habitat Disturbance
• Fire and fire-dependent species
• Ex Peters 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

14

• Biodiversity Factors
• 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
• Fragments may not support self-sustaining
  populations

15

• Mount Hood National Forest, Oregon
• Patches due to timber removal

16

• Biodiversity Factors
• 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
• Fragments may not support self-sustaining
  populations

17

• 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

18

• 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

19
(No Transcript)
20

• 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

21
Nile perch Lake Victoria
Brown tree snake - Guam
Argentine ants - California
Caulerpa taxifolia - California
22
How might we justify a particular environmental
ethic?

• 1. Anthropocentrism
• 2. Moral extentionism
• zoocentrism/sentientism/psychocentrism, and
  biocentrism
• 3. Novel features or entirely new approach such
  as ecocentrism

23
Albert Schweitzer (1875-1965)Reverence for Life

• A predecessor to later biocentric environmental
  ethics.
• Life is good in itself, inspiring, and deserving
  of respect I am life which wills to live, in
  the midst of life which wills to live.
• Schweitzers reverence for life can be
  interpreted as an attitude, moral virtue, or
  character traitenvironmental virtue ethics.
• But Schweitzer seemed to regard reverence for
  life as reverence for life in and of itself, akin
  to an ethical norm or rule. This, however, leads
  to Schweitzers paradox.

24
On Being Morally Considerable (1978)Kenneth
Goodpaster

• What makes something morally considerable?
• Animal ethics people correctly argue that it is
  arbitrary to stop at something like rationality
  and that sentience is morally considerable
  because, in part, rationality presumes sentience.
  
• But why stop at sentience?
• Sentience presumes something more basic that
  something is alive.
• Goodpaster To avoid arbitrary
  distinctions, we should
• ground morality
  in a life criterion anything
• alive is morally
  considerable.

25
Respect for Nature A Theory of Environmental
Ethics (1986)

• Paul W. Taylor

26
Another Biocentric Environmental Ethic

• Gary Varner
• Varner develops a psycho-biological theory of
  individual welfare.

27
And Another Biocentric Environmental Ethic

• Nicholas Agar
• Agar develops a theory based on living things
  having bio-preferences.

28
And Still Another Biocentric Environmental Ethic

• James Sterba uses liberal justice to ground a
  biocentric environmental ethic
• An organism has a good of its own if it can be
  harmed or benefited.
• If an organism has a good of its own, it is wrong
  to harm it unless we have a good reason for doing
  so.
• There are no non-question-begging reasons to
  assume that human interests always override the
  good of a nonhuman organism.
• An organism that has a good of its own has moral
  standing and is thus subject to the same
  fundamental principles of justice that govern
  human relationships.
• Liberal justicea balancing of liberty and
  equalityis the most defensible principle of
  social justice to guide human-nonhuman
  relationships.
• Sterba argues that species and ecosystems can
  also be said to have goods of their own.
  Sterbas EE thus bridges biocentrism and
  ecocentrism.

29
Aldo Leopolds Land Ethic
30
Ecocentrism

• Ecocentrists believe that anthropocentrism,
  zoocentrism, and biocentrism are all inadequate
  because of their individualist focus.
• From ecology We cannot fully understand an
  organism without also examining things such as
• its species
• its interaction within species populations
• its relationship with ecosystem processes
• what it eats
• what eats it
• etc.
• Ecocentrism We cannot fully understand the
  value of an organism without also locating value
  in holistic entities, and probably also in
  processes and relationships.

31
Ecocentrism

• The central feature of ecocentrism is its holism.
  
• Three kinds of holism
• Epistemological or methodological holism We
  cannot understand something or have knowledge of
  it without taking into account holistic entities,
  processes, and relationships.
• Metaphysical holism Holistic entities really
  exist.
• Ethical holism holistic entities (and probably
  processes and relationships as well) have
  noninstrumental value.

32
Three Problems for Ecocentrism

1. Getting its ecology right
2. Naturalistic fallacy Trying to derive values
   straight from facts, or prescriptive norms about
   what we should do straight from descriptive,
   factual statements
3. Ecofascism

33
Animal Liberation A Triangular Affair (1980)
by J. Baird Callicott

• Ethical Humanism
  (Anthropocentrism)
• Humane Moralism
  Leopolds Land Ethic
• (Animal Liberation)
  (Holistic Ecocentrism)

34
Callicotts Conclusions

• Animal liberationists fail to make a distinction
  between domestic and wild animals, but this
  distinction is crucial.
• From the perspective of Aldo Leopolds land
  ethic, many domestic animal species ruin nature.
• Domestic animals have no natural behavior.
• We cannot liberate animals back to the wild if
  left alone, many domesticated species might go
  extinct.
• It is wrong to prevent pain (sentientism) because
  pain provides important information for nervous
  systems.
• Animal liberation denies our natural
  participation in nature through activities such
  as hunting.

35
Animal Liberation versus the Land Ethic (1981)
by Edward Johnson

• Johnson replies to Callicott
• Animal liberation is directed toward individual
  animals that can be liberated there is no direct
  concern with species.
• The sentientist point about pain is that
  pointless pain is morally wrong.
• Natural participation with nature? Whats this?

36
Tom Regan pours fuel on the fire between animal
ethics and environmental ethics (1983)

• The implications of Leopolds view include the
  clear prospect that the individual may be
  sacrificed for the greater biotic good, in the
  name of the integrity, stability, and beauty of
  the biotic community. It is difficult to see
  how the notion of the rights of the individual
  could find a home within a view thatmight be
  fairly dubbed environmental fascism. To use
  Leopolds telling phrase, man is only a member
  of the biotic team, and as such has the same
  moral standing as any other member of the
  team. If, to take an extreme, fanciful but, it
  is hoped, not unfair example, the situation we
  faced was either to kill a rare wildflower or a
  (plentiful) human being, and if the wildflower,
  as a team member, would contribute more to the
  integrity, stability, and beauty of the biotic
  community than the human, then presumably we
  would not be doing wrong if we killed the human
  and saved the wildflower. (pp. 361-362 from The
  Case for Animal Rights, 1983, bold and underline
  added)

37
Animal Liberation and Environmental Ethics Bad
Marriage, Quick Divorce (1984)

• Mark Sagoff
• If animal liberationists such as Singer are
  committed to minimizing the suffering of animals,
  logically they should be committed to intervening
  in wild nature to lessen suffering. This could
  lead to many proposals and policies such as
  killing predators.
• But these kinds of proposals and policies will
  strike an environmentalist as being absurd.
• Thus, a holistic environmental ethic cannot stem
  from the interests of individual animals.

38
A Possible Utilitarian Response

• Utilitarian intervention to minimize suffering in
  the lives of wild animals might damage
  ecosystems, resulting in a lower quality of life
  for animals in the wild (and possibly a lower
  quality of life for people).
• Removal of animals from the wild to minimize
  suffering might likely lead to unhappier lives
  for the now captive animals.
• Thus, leaving wild animals alone might be our
  best policy to minimize animal suffering. This
  could result in a habitat ethic that might be
  compatible with holistic environmental ethics.

39
A Possible Animal Rights Response

• A wild animals right to life is a right not to
  be killed by moral agents (who have a duty to
  respect rights), but this doesnt imply a duty on
  the part of moral agents to protect the animal
  from being killed by non-moral agents such as
  other wild animals.
• We should manage human wrongs and not wild
  animals.
• Thus, respecting the rights of wild animals
  simply means letting them be, with as little
  human interference as possible.

40
Animal Liberation is an Environmental Ethic
(1998) by Dale Jamieson

• Sentient humans and animals have primary value,
  while non-sentient entities have derivative
  value. But in some cases derivative value should
  trump primary value.
• Animal liberation and environmental ethics can be
  likened to a Hollywood romance
• 1. They can complement each otherthere are
  good animal
• ethics and good environmental ethics reasons to
  not eat meat.
• 2. We can value non-sentient nature
  intrinsically and intensely.
• 3. An animal ethic can give us a habitat ethic
  that is
• indistinguishable from a biocentric or
  ecocentric
• environmental ethic