Download Species Diversity

Species Diversity
Alpha, Beta, and Gamma
Diversity
• alpha ~ number in a small area or ecosystem
• beta ~ rate of change across habitats; how quickly do you gain
species as you move out of one habitat and into another
• gamma ~ changes across landscape level gradients
• Alpha is a count, beta and gamma are rates of change
What is a species?
• Biological species: a group of populations whose individuals
have the potential to interbreed and produce fertile
offspring.
• Problems with the biological species concept
• hybrids, especially in plants, but also in animals and asexually
reproducing organisms
• highlights importance of maintaining genetic diversity below the
species level
• Evolutionary Significant Unit (ESU)
• a population significantly different ecologically or genetically than
other groups of the same species
• how much is “significant”?
• Distinct Population Segment
• similar to ESU, but can also be based on political boundaries
• convenient for management, not very scientific
How Many Species Exist?
• 1.7 million described using the Linnean system
• Somewhere between 10 and 100 million
• 13 million used as a working estimate
• Estimates based on known species
• Cryptic species are a source of underestimation, as are those
that are difficult to identify (bacteria)
• A lot to lose and a lot to learn!
Intrinsic Value
• Value independent of its usefulness to people or the
ecosystem
• If you accept this, conservation priorities are easy, protect by
risk.
Lists
• IUCN Red List
• Convention on International Trade in Endangered Species
(CITES)
• National and State Lists
• Red List categories
• Extinct: over 1000 species have gone extinct since 1600
• Extinct in the Wild: dozens EW or successfully reintroduced after
being EW
• Critically Endangered: extremely high risk of extinction in the wild
• Endangered: very high risk of extinction in wild
• Vulnerable: high risk, most threatened species fall in here
• Near Threatened: Close to qualifying as threatened
• Least Concern: Widespread and abundant
• Data Deficient and Not Evaluated: Majority of species are NE
Red List Criteria
• Reduction in population size of 30-90%
• Geographic range small, isolated, or only known from a single
site or decreasing; occurrence/occupancy under extreme
fluctuation
• Small and declining population size
• Quantitative analysis showing probability of extinction in the
wild is 50% in 10 years or three generations.
Understanding Rarity
• Geographic range: local endemics, rare because they only live
in one small place
• Habitat specialists: Occur in specific and rare habitats, rare
because their habitat is rare
• Local population size: occur at low densities
• Some relatively abundant species very threatened, some rare
species have stable populations
• Should the rare ones be listed?
Understanding Abundance
• Abundance does not guarantee security
• American chestnut
• Passenger pigeon
Instrumental Value
• Food
• includes microorganisms like bacteria and yeast
• wild relatives of domestic species
• yaks and buffalo endangered, wild auroch extinct in 1627
• wild species as sources of new domesticates
• Wild plants and animals
• Medicine, both traditional and modern
• Silphion was a wild plant used as a contraceptive. Went extinct by 77 AD because
of over-exploitation.
• Textiles, construction materials, trinkets, luxury goods
• wood, furs, ivory
• Fuel, Oils, and Waxes
• Recreation, Pets, Ornamental Plants, and Ecotourism
• Ecosystem Services
• pollination (valued at $200 billion), nutrient cycling, water quality control
Spiritual Value
• Biophilia
• existence values
Scientific and Educational
• Template for engineering and design
• airplane wings
• radar and sonar
• Studies of genetics and evolution
Ecological Values
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Species interactions
Ecosystem structure
Ecosystem function
Some species values more than others
• dominant species ~ abundant
• controller species ~ control flow of energy and nutrients
• keystone species ~ role disproportionately larger than abundance
• Ecological extinction occurs when a species is too rare to fulfill
its ecological role
• Ecosystem roles can change over longer time periods
Strategic Values
• Flagship species
• Charismatic
• Umbrella species
• Charismatic and have broad patterns of ecosystem use
• Conservation of this species, will conserve a lot of others
• Indicator species
• Easy to monitor
• Provide information about ecosystem health or status of other
species
Realized and Potential Values
• Gap between currently realized values and potential future
values
Uniqueness Values
• Some genera have hundreds of species, some have only one
• More relatives? More replaceable
• or at least a suitable approximation
• but you can wipe out a whole group that way
• fishing down the food web
• Species that overlap functionally less valuable than ones that
do not.
• Taxonomic levels arbitrary
Which values do we choose for
conservation prioritization
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Intrinsic ~ protect by risk
Instrumental ~ protect by usefulness
Spiritual
Scientific & Educational ~ conservation of model organisms?
Ecological
Strategic ~ flagship, umbrella, indicator
• problems with indicators as a target?
• Potential Future Value?