Chapter 16: Biological Resources
Biological Diversity
 Species: a group of more or less distinct organisms that are capable of
interbreeding with one another in nature to produce fertile offspring but do
not interbreed with other organisms
 1.9 million species have been named and described
 Biological diversity is the variability of Earth’s organisms
o Consists of 3 components: genetic diversity, species richness, and
ecosystem diversity
 Why we need organisms
o In primitive societies species contribute food, clothing, and shelter
o In industrial societies humans still depend on species
o Many species have not been evaluated for their potential usefulness
o Insects, bacteria, and fungi are very important to humans
 Ecosystem services and species richness
o Ecosystem services are important environmental benefits that
ecosystems provide to people. They maintain the living world and we
are completely dependent on these basic support services
o Species richness within an ecosystem provides it with resilience,
which is the ability to recover from environmental changes/disasters
 Genetic reserves
o Maintenance of a broad genetic base is critical for each species’ longterm health and survival
o By crossing “super strains” with more genetically diverse relatives,
disease and pest resistance can be introduced into such plants
 Scientific importance of genetic diversity
o Genetic engineering, the incorporation of genes from one organism
into a different species, makes it possible to use the genetic resources
of organisms on a wide scale
o We do not have the ability to make genes that encode specific traits
o It takes 100s of years for evolution to produce the genetic diversity
found in organisms living on our planet today
 Medicinal, agricultural, and industrial importance of organisms
o Genetic resources of organisms are vital to the pharmaceutical
industry, which incorporates many hundreds of chemicals derived
from organisms
o Agriculture is important because it provides us food, yet the kinds of
foods we eat are limited compared to the total number of edible
species
o Industrial technologies require many things from organisms
 Plants give oil, perfumes, dyes, papers
 Animals provide wool, silk, fur, leather
 Insects secrete a lot of chemicals that represent a lot of
potential products
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Aesthetic, ethical, and spiritual value of organisms
o Organisms provide mental health benefits, recreation, inspiration, and
spiritual solace
o Artists, writers, and poets have tried to capture the beauty of the
physical world
o Parks and green space promote psychological well-being
Extinction and Species Endangerment
 Extinction: the death of the last individual of a species
 Extinction is irreversible
 During the time span in which organisms have occupied Earth, a continuous,
low-level extinction of species, or background extinction, has occurred
 A mass extinction has occurred maybe 5 or 6 times
 Endangered species act 1973
 Endangered and threatened species
o Endangered species are a species that faces threats that may cause
them to become extinct within a short period of time
o A threatened species is a species whose population has declined to the
point that it may be at risk of extinction
o Endangered and threatened species represent a decline in biological
diversity, long term survival requires genetic diversity
 Characteristics of endangered species
o Characteristics include small range, having low reproductive success,
having specialized feeding habits
o Habitat fragmentation is a major threat to long-term survival of many
species
 Where is declining biological diversity the greatest problem?
o Declining biological diversity is a concern throughout the US, but it is
most serious in Hawaii (63% of species are at risk) and California
(29% of species are at risk)
o Tropical rain forest in south and central America, central Africa, and
southeast Asia are also subject to declining biological diversity
 Earth’s biodiversity hot spots
o Norman Myers coined the term biodiversity hotspots
 Biodiversity hotspot: relatively small areas of land that contain
an exceptional number of endemic species and are at high risk
from human activities
o Meyers and ecologists identified 25 biological hotspots
 Human causes of species endangerment
o In 2001 the United Nation requested a Millennium Ecosystem
Assessment in order to gather information about ecosystem changes
and the effects of these changes on human well-being
o Biological diversity is declining rapidly due to several factors
 The greatest threat to biological diversity is land use change
 Land use change
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o Most species faced with extinction today are endangered because of
the destruction, fragmentation, or degradation of habitats by human
activities
o As the human population grows, more species face endangerment
o Little habitat remains for endangered species
Invasive species
o Biotic pollution is the introduction of a foreign species into an
ecosystem in which it did not evolve
 These often upset the balance among the organisms living in
that area and interfere with the ecosystems normal functioning
o The foreign species competes with native species
o Humans are usually responsible for invasive species
Overpopulation
o Species can come extinct or endangered as a result of deliberate
efforts to eradicate or control their numbers
 Ranchers, hunters, and government agents are some of the
people that cause this
 Poaching is a major threat
o Commercial harvest is the collection and sale of live organisms from
nature
 These end up in zoos, aquaria, biomedical research
laboratories, circuses and pet stores
o Wild bird conservation act of 1992 imposed a moratorium on
importing rare bird species
Pollution
o Humans produce acid rain, stratospheric ozone depletion, and climate
change
 All of these degrade the environment
o Climate change is caused by an increase of carbon dioxide in the
atmosphere
o Pollution can cause deformities in animals
Conservation Biology
 Conservation biology is the scientific study of how humans impact organisms
and of the development of ways to protect biological diversity
 A single large area of habitat is generally more effective at safeguarding an
endangered species than several habitat fragments
 It is more effective to work on preserving intact ecosystems
 In situ conservation (on-site conservation) concentrates on preserving
biological diversity in nature
o Conserving is the single best way to preserve biological diversity
o Protected areas are not always effective in protecting biological
diversity
 Developing countries
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o 11.5% of Earth’s land area has been set aside to protect biological
diversity
Ex situ conservation (off-site conservation) involves conserving biological
diversity in human-controlled settings
Connecting fragmented habitats
o Habitat corridors are strips of habitat that connect isolated habitat
fragmented
 These are also called wildlife corridors
o Restoration ecology is the study of the historical condition of a
human-damaged ecosystem, with the foal of returning it as close as
possible to its former state
Zoos, aquaria, botanical gardens, and see banks
o All of these save individual species who are on the brink of extinction
o Artificial insemination is when sperm is collected from a suitable male
of a rare species and used to artificially impregnate a female
o Embryo transfer is when a female is treated with fertility drugs, then
the eggs are collected and fertilized with sperm
Reintroducing endangered species to nature
o Only one of every 10 reintroductions using animals raised in captivity
is successful
o Once animals are released the have to be monitored
Seed banks
o Seed banks, or gene banks, are more than 100 seed collections
o Seeds to do not remain alive indefinitely and must be germinated
periodically so that new seeds can be collected
o The biggest disadvantage to seed banks is that plants stored in this
manner remain stagnant in an evolutionary sense
Conservation organizations
o These group educate policymakers and the public about the
importance of biological diversity
Conservation Policies and Laws
 Endangered species act was passed to authorize the US Fish and Wildlife
services to protect endangered and threatened species in the US and abroad
 The ESA requires the FWS to select critical habitats and design a detailed
recover plan for each species listed
 Habitat conservation plans
o Habitat conservation plans: the 1982 amendment of the ESA provided
a way to resolve conflicts between protection of endangered species
and development interest on private property
o The habitat conservation plan allow a landowner to take a rare
species if the taking does not threaten the survival or recovery of the
threatened or endangered species on that property
 International conservation policies and laws
o The World Conservation Strategy is a plan designed to conserve
biological diversity worldwide
o The Convention on Biological Diversity was produced to decrease the
rate of extinction of the worlds endangered species
 National conservation strategy: a detailed plan for managing
and preserving the biological diversity of that specific country
o The Convention on International Trade in Endangered Species of Wild
Flora and Fauna controls the exploitation of endangered species
internationally
Wildlife Management
 Wildlife management: the application of conservation principles to manage
wild species and their habitats for human benefit or for the welfare of other
species
 Attention is focused on common organisms
 Management of migratory animals
o International agreements are established to protect migratory
animals
 Flyways: established routes of migration
 Arctic snow geese
o The artic snow goose is a major challenge for wildlife manager
because its population expanded rapidly beginning in the 1980s
o The pop. Migrates south during the autumn and spends winters in salt
marshes in Texas and Louisiana
o Wildlife managers want to avoid a massive die-off of geese in the
Arctic so they need to reduce the population
 Management of aquatic organisms
o Fishes with commercial or sport value must be managed to ensure
hey are not overexploited to the point of extinction
o During the 19th and 20th centuries whale species were harvested to
the point of commercial extinction, which is when so few remain that
it is unprofitable to hunt them