Species Diversity

Species Diversity
What is a species?
 Species = Latin for “kind” or “appearance”
 Linnaeus described species in terms of their morphology
 Modern taxonomists also consider genetic makeup and functional and
behavioral differences when describing species
The biological species concept (BSC) emphasizes reproductive isolation
 Ernst Mayr 1942
 A biological species is defined as a population or group of populations whose
members have the potential to interbreed and produce viable, fertile offspring
but cannot do so with members of other species
– The species is the largest unit of population in which gene flow is possible
– It is defined by reproductive isolation from other species in natural
environments (hybrids may be possible in the lab or in zoos)
Other species concepts
How many species are there?
 Estimates range from 4 - 112 million species, of which only 1.7 million have
been described
 14 million is a good compromise
Where is biodiversity high?
 Only 10-15% of species identified are found in North America and Europe
 Greatest concentration of species in tropical rainforests and coral reefs
 Biodiversity hotspots
– Have exceptional numbers of endemic species
Biodiversity hotspots
Amazing diversity
Taxonomic difficulties
 Sister or cryptic species
Intrinsic and Instrumental Value
 Instrumental (Utilitarian, Conferred) - Worth or value only because they are
valued by someone who matters
– Anthropocentric
 Intrinsic (Inherent, Innate) - Worth or value simply because of existence
– Biocentric or ecocentric
Endangered Species Act (ESA)
 ESA provides “..a means whereby the ecosystems upon which endangered
species and threatened species depend may be conserved, and to provide a
program for the conservation of such endangered species and threatened
Endangered Species Act (ESA)
 Species, subspecies and populations are listed as either endangered or
threatened (all referred to as “species”)
– An Endangered Species is any species which is in danger of extinction
throughout all or a significant portion of its range
– A Threatened Species is any species which is likely to become an
endangered species within the foreseeable future throughout all or a
significant portion of its range
Endangered Species Act (ESA)
 Administered by the US Fish and Wildlife Service, Department of the Interior
 The Secretary of the Interior may not take into account the economic effects
that listing may have on the area where the species occurs
 Congress felt that listing was fundamentally a scientific question - Is the
continuation of the species in jeopardy?
Convention on International Trade on Endangered Species (CITES)
 At least 126 signatory countries
 Goal to regulate the complex wildlife trade by controlling species-specific trade
levels on the basis of biological criteria
– 900 species - trade prohibited
– 5,000 animals & 28,000 plants trade regulated
 The International Union for the Conservation of Nature and Natural Resources
is a network of 500 governmental and nongovernmental organizations from
116 countries, joined together to promote the protection and sustainable use of
living resources
 One of its primary functions is to monitor the status of ecosystems and species
throughout the world
 “Red Data Books”
– global catalogs of threatened organisms
– www.redlist.org
 Data from which the listings are made are gathered from literature searches
and from correspondence with specialists around the world
– Based on this information species are assigned to categories
 Difficulties in making assessments of endangerment
 What about naturally rare species?
Instrumental values
 All food is biodiversity!
Potential food
 As many as 80,000 edible wild plant species could be utilized by humans
Genetic material
 More than half of all prescriptions contain some natural product
 Pharmaceutical companies actively prospect tropical countries for products ethnobotany
 Contraceptive properties
 Worth more than its weight in silver
Clothing, shelter, tools, trinkets, fuel
 Use of resources without physically extracting/degrading them
– Photosynthesis, pollination, soil formation, waste disposal, air and water
purification, nutrient cycling, etc. all depend on biodiversity
 USFWS estimates Americans spend $104 billion annually on wildlife-related
 “Biophilia” - E.O. Wilson
 Aesthetic reasons
 Existence value
Scientific/educational values
Ecological values
 Dominant and controller species play important roles in ecosystems
 Ecological extinction can occur if species does not have high enough numbers
to fill its role in an ecosystem
Keystone species
Precautionary principle
 Assume all species are important until proven otherwise
Are all species equal in conservation?
Strategic species
Flagship species
Umbrella species
Indicator species
Vulnerable species
Economically important species
Realized vs. potential value
 Thermus aquaticus
 Yew
Uniqueness value