I.
Miller Chapter 9 Review
Chapter 9: Sustaining Biodiversity – Saving Species and Ecosystem Services
a. 9-1: What Role do Humans Play in the Loss of Species and Ecosystem Services?
i. Biological Extinction – when a species can no longer be found anywhere on the
earth.
1. The loss of a keystone species or a major reduction in its populations can
lead to population declines or extinctions of species with strong connections
to such species and to a breakdown in ecosystem services that depend on
those connections --- called a trophic cascade
2. These declines can also result in degradation of habitats and ecosystem
series such as chemical cycling and energy flows
ii. Mass Extinction – the extinction of many species in a relatively short period of
geologic time
1. Earth has experienced 5 mass extinctions
a. After each mass extinction, the earth’s overall biodiversity eventually
returned to equal or higher levels, but each recovery required millions
of years
2. The cause of past mass extinctions are poorly understood but probably
involved global changes in environmental conditions
a. Examples: sustained and significant global warming or cooling – large
changes in sea level – catastrophes such as multiple large-scale
volcanic eruption
iii. Extinction is a natural process
1. Background Extinction Rate – the rate that existed before modern humans
evolved some 200,000 years ago
2. Scientific evidence indicated that extinction rates have risen in some areas as
human populations have spread over most of the globe, destroying and
degrading habitats, consuming huge quantities of resources, and creating
large and growing ecological footprints
a. Example: there are 10 million (this makes the problem easier) species
on earth. At the background extinction rate of 1 species per million
per year, about 10 species would disappear naturally each year.
HOWEVER at today’s estimated rate of 100 to 1,000 times the
background rate, we are losing between 1,000 and 10,000 species per
year or between 2 and 27 species every day on average.
3. This would amount to a sixth mass extinction cause primarily by human
activities with much of it taking place within just one century.
a. With the loss of such a huge portion of the planet’s biodiversity, we
would also likely loss whole ecosystems that depend on the vanishing
species, along with the vital ecosystem services the provide, including
air and water purification, natural pest control, and pollination
iv. Reasons for a projection of 10,000 times the background extinction rate to happen:
1. Both the rate of extinction and the resulting threats to ecosystem services are
likely to increase sharply during the next 50-100 years because of the
harmful environmental impacts of the rapidly growing human population
and its growing use of resources per person
2. The current and projected extinction rates in the world’s biodiversity
hotspots – areas that are highly endangered centers of biodiversity – are
much higher than the global average
3. We are eliminating, degrading, fragmenting, and simplifying many
biologically diverse environments – including tropical forests, coral reefs,
wetlands, and estuaries – that serve as potential sites for the emergence of
new species.
a. We may be limiting the long-term recovery of biodiversity by
eliminating these places where new species can evolve – aka creating
a speciation crisis
v. Endangered Species – has so few individual survivors that the species could soon
become extinct.
vi. Threatened Species (Vulnerable Species) – still has enough remaining individuals to
survive in the short term, but because of declining numbers, it is likely to become
endangered in the near future
vii. Types of extinction:
1. Regionally Extinct – in the areas where they are normally found
2. Functionally Extinct (extinction of ecological interactions) – when their
populations crash to the point where they can no longer play their functional
roles in an ecosystem – when a species’ numbers drop to a certain point, its
interactions with other species are lost or greatly diminished.
b. 9-2: Why Should We Care about Sustaining Species and the Ecosystem Services They
Provide?
i. Three major reasons why we should work to prevent our activities from causing or
hastening the extinction of other species
1. World’s species provide vital ecosystem services that help to keep us alive
and support our economics
a. Many species also contribute to economic services on which we
depend
i. Bioprospectors search tropical forest and other ecosystems to
find plants and animals that scientist can use to make
medicinal drugs
ii. Phytochemicals – certain chemicals such as antioxidants that
occur naturally in plants – have the potential to slow aging,
reduce pain, and help us to reduce our weight, prevent various
cancers, and control diseased such as diabetes
iii. Economic benefit from wildlife tourism, or ecotourism
2. That analysis of past mass extinctions indicated it will take 5 million to 10
million years for natural speciation to rebuild the biodiversity that is likely to
be lost during this century.
3. Many people believe that wild species have right to exist, regardless of their
usefulness to us
c. 9-3: How do Humans Accelerate Species Extinction and Degradation of Ecosystem
Services?
i. HIPPCO (Habitat Invasive Population Pollution Climate Overexploitation) – the
most important direct cause of extinction and threats to ecosystems series
1. Habitat destruction, degradation, and fragmentation
a. The greatest threat to wild species
b. Deforestation in tropical areas - Destruction and degradation of
coastal wetlands and coral reefs - Plowing of grasslands - Pollution of
streams, lakes, and rivers
c. Island species – many of them found nowhere else on earth – are
especially vulnerable to extinction when their habitats are destroyed,
degraded, or fragmented because they have nowhere else to go
d. Habitat Fragmentation – occurs when a large, intact, area of habitat
such as a forest or natural grassland is divided, typically by roads,
logging operations, crop fields, or urban developments, into smaller,
isolated patches or habitat islands
i. Can also divide populations of a species into smaller,
increasingly isolated groups that are more vulnerable to
predators, competitor species, disease, and catastrophic events
such as storms and fires
ii. Creates barriers that limit the abilities of some species to
disperse and colonize new areas, to locate adequate food
supplies, and to find mates
iii. Most National Parks and other nature reserves are habitat
islands, many of them surrounded by potentially damaging
logging and mining operations, coal-burning power plants,
industrial activities, and human settlements
1. Freshwater lakes are also habitat islands
2. Invasive (nonnative) species
a. The deliberate or accidental introduction of harmful species into
ecosystems
i. Many introductions of nonnative species have been beneficial
to use – control pest
b. The problem is when they are introduced in their new habitats, some
introduced species do not face the natural predators competitors,
parasites, viruses, bacteria, or fungi that had helped to control their
numbers in their original habitats.
i. When this occurs they are now viewed as invasive species
c. Case Study – Kudzu Vine and Kudzu Bug
i. A deliberately introduced plant species (Kudzu Vine) –
imported from Japan and planted in the southeastern US to
help control soil erosion
ii. Kudzu vine is very difficult to kill, even with the use of grazing
goats and herbicides, which can also damage other plants and
contaminate water supplies
1. Could spread to the north if the climate gets warmer as
scientist project
2. Almost every part of the kudzu plant is edible
iii. Kudzu Bug (Stinkbug)– the pea-sized bug that spreads evenly
more rapidly than the kudzu vine, and it also feeds on
soybeans and thus could pose a major threat to soy crops
1. Some pesticides can kill this bug, but might end of
boosting their numbers by promoting genetic resistance
to the pesticides
2. Also evaluating the use of a wasp whose larvae attack
kudzu bug embryos
d. Nonnative invaders arrive from other continents as stowaways on
aircraft, in the ballast water of tankers and cargo ships, and as
hitchhikers on imported products such as wooden packing crates
e. Once a harmful nonnative species because established in an
ecosystem, its removal is almost impossible – somewhat like trying to
collect smoke after it has come out of a chimney – the best way to
limit the harmful impacts of nonnative species is to prevent them
from being introduced into ecosystems
i. Funding a massive research program
ii. Greatly increasing ground surveys and satellite observations
iii. Identifying major harmful invader species and establishing
international treaties
iv. Requiring cargo ships to discharge their ballast water
v. Educating the public
3. Population growth and increasing use of resources
a. Past and projected human population growth and rising rates of
resources use per person have greatly expanded the human ecological
footprint – acting together, these two growth factors have caused the
extinction of many species
i. A chemical derived from the pesticide DDT was magnified as it
moved up through their food web through processes called
bioaccumulation and biomagnification
ii. Climate change – could help to drive a quarter to half of all land
animals and plants to extinction by the end of this century
1. Example: Polar Bear – is threated because of the higher
temperatures and melting sea ice in its polar habitat
a. Scientific measurements reveal that the earth’s
atmosphere has been getting warmer since 1975
and that this warming is occurring twice as fast
in the Artic as in the rest of the world. Thus artic
ice is melting faster than the average annual area
of floating sea ice in the Arctic during the
summer is decreasing - shortening the polar
bears’ hunting season
b. Some protected species are illegally killed (poached) for their
valuable parts of are sold live to collectors
i. Around the globe, the legal and illegal trade in wild species for
sue as pets is a huge and very profitable business
ii. Indigenous people in much of West and Central Africa have
sustainably hunted wildlife for bush meat as a source of food
1. Some areas have skyrocketed as hunters have tried to
provide food for rapidly growing populations or to
make a living by supplying restaurants in major cities
with exotic meats from gorillas and other species
c. Case Study: A Disturbing Message from the Birds
i. Approximately 70% of the world’s more than 10,000 known
bird species are declining in numbers, and much of this decline
is related to human activities (HIPPCO)
ii. Threatened with extinction mostly by habitat loss, degradation,
and fragmentation (H in HIPPCO)
iii. The US are endangered, threatened, or in decline, mostly
because of habitat loss and degradation invasive species, and
climate change
iv. Birds are an indicator species because they live in every
climate and biome, respond quickly to environmental changes
in their habitats, and are relatively easy to track and count
v. Perform critically important economic and ecosystem services
in ecosystems throughout
4. Pollution
a. Can threaten some species with extinction
5. Climate Change
6. Overexploitation
d. 9-4: How Can We Sustain Wild Species and Their Ecosystem Services
i. Convention on International Trade in Endangered Species (CITES) – 1975 – signed
by 178 countries, bans the hunting, capturing, and selling of threatened or
endangered species
1. List 926 species that are in danger of extinction and cannot be commercially
traded as live specimens or for their parts or products.
2. Restricts international trade of roughly 5,000 species of animals and 29,000
species of plants that are at risk of becoming threatened.
a. Includes elephants, crocodiles, cheetahs, and chimpanzees
i. But the effects of this treaty are limited because enforcement
varies from country to country and convicted violators often
pay only small fines
ii. Convention of Biological Diversity (CBD) – ratified or accepted by 193 countries (as
of 2012 the US is not included).
1. It legally commits participating governments to reducing the global rate of
biodiversity loss and to equitably sharing the benefits from the use of the
world’s genetic resources.
a. Includes efforts to prevent or control the spread of ecologically
harmful invasive species
i. Focuses on the ecosystems rather than on individual species,
and it links biodiversity protection to issues such as the
traditional rights of indigenous people
b. Implementation has been slow – the law contains no severe penalties
or other enforcement mechanisms
iii. Case Study – The U.S. Endangered Species Act
1. Endangered Species Act 1973 (ESA: amended in 1982, 1985, and 1988) – was
designed to ID and protect endangered species in the United States and
abroad. Is probably the most far-reaching environmental law ever adopted
by any nation, which has made it controversial
a. National Marine Fisheries Service (NMFS) – responsible for ID and
listing endangered and threatened ocean species,
b. U.S. Fish and Wildlife Service (USFWS) – is to ID and list all other
endangered and threatened species
c. The ESA also forbids federal agencies (except the Defense
Department) to carry out, fund, or authorize projects that would
jeopardize any endangered or threatened species or destroy or
modify its critical habitat
d. Since 1995, there have been numerous efforts to weaken the ESA and
to reduce its already meager annual budget
i. Opponents of the act contend that it puts the rights and welfare
of endangered plants and animals above those of people
ii. Biologist insist that is has not been a failure, for three main
reasons:
1. Species are listed only when they face serious dangers
of extinction
2. According to federal data, the conditions of more than
half of the listed species are stable or improvement
iv.
v.
vi.
vii.
3. The 2012 budget for protecting endangered species
amounted to an average expenditure of about $.86 per
U.S. citizen
e. The U.S. also needs a new law that emphasizes protecting and
sustaining biological diversity and ecosystem services rather than
focusing mostly on saving individual species
1903 – President Theodore Roosevelt established the first U.S. federal wildlife
refuge at Pelican Island, Florida
Seed Banks – preserve genetic information and endangered plant species by storing
seeds in refrigerated, low-humidity environments
1. We can take pressure off some endangered or threatened species by raising
individuals of these species on farms for commercial sale
Zoos, aquariums, game parks, and animal research centers are being use to preserve
some individuals of critically endangered animal species, with the long-term goal of
reintroducing the species into protected wild habitats
1. Two techniques for preserving endangered terrestrial species
a. Egg pulling – involves collecting wild eggs laid by collecting
endangered bird centers and then hatching them in zoos or research
centers
b. Captive Breeding – some or all of the wild individuals of a critically
endangered species are collected for breeding in captivity, with the
aim of reintroducing the offspring into the wild
2. Other techniques for increasing the populations of captive species include
artificial insemination, embryo transfer (surgical implantation of eggs of ones
species into a surrogate mother of another species), use of incubators, and
cross fostering (in which the young of a rare species are raised by parents of
a similar species)
3. The ultimate goal of captive breeding programs is to build up populations to
a level where they can be reintroduced into the wild
a. Successes include the black-footed ferret, the golden lion tamarin
(monkey species), the Arabian oryx, and the California condor
4. Most reintroductions fail because of lack of suitable habitat, inability of
individuals bred in captivity to survive in the wild, and renewed overhunting
or poaching
a. One problem for captive breeding programs is that a captive
population of an endangered species must typically number 100-500
individuals in order for it to avoid extinction through accident,
disease, or loss of genetic diversity through inbreeding
Precautionary Principal – when substantial preliminary evidence indicates that an
activity can harm human health or the environment, we should take precautionary
measures to prevent or reduce such harm even if some of the cause-and-effect
relationships have not been fully established scientifically
1. “Better safe than sorry” and “Look before you leap”
2. Both the preservation of species and protections of entire ecosystems and
their ecosystem services – used as a strategy for dealing with other
challenges such as preventing exposure to harmful chemicals in the air we
breathe, the water we drink, and the food we eat
3. Ask 3 important questions:
a. Focus mostly on protecting species or on protecting ecosystems and
the ecosystem services?
b. How do we decide which species should get the most attention in our
efforts to protect as many species as possible?
c. How do we determine which habitat areas are the most critical to
protect?