Transcript keystone species

Community Ecology
• Each species has a particular ecological
niche or role that it plays in an ecosystem.
r-Selected Species
Cockroach
Dandelion
Many small offspring
Little or no parental care and protection of offspring
Early reproductive age
Most offspring die before reaching reproductive age
Small adults
Adapted to unstable climate and environmental
conditions
High population growth rate (r)
Population size fluctuates wildly above and below
carrying capacity (K)
Generalist niche
Low ability to compete
Early successional species
Characteristics of
Successful
Invader Species
Characteristics of
Ecosystems Vulnerable
to Invader Species
• High reproductive rate,
short generation time
(r-selected species)
• Similar climate to habitat of
invader
• Pioneer species
• Absence of predators on
invading species
• Long lived
• High dispersal rate
• Release growthinhibiting chemicals into
soil
• Generalists
• High genetic variability
• Early successional systems
• Low diversity of native
species
• Absence of fire
• Disturbed by human
activities
Cockroaches: Nature’s Ultimate
Survivor
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Appeared in the geologic record 350
million years ago.
Classic r-strategist = “generalist”
Eat almost anything including algae,
dead insects, salts in tennis shoes,
electrical cords, glue, paper, soap, and
weaker cockroaches.
Some species can go for months without
food, last a month without water,
withstand massive doses of radiation,
one species can even survive being
frozen for 48 hours.
High reproductive rates (1 female can
produce 10 million offspring in one year)
Carry viruses that cause hepatitis, polio,
typhoid, and salmonella.
60% of the 12 million Americans suffer
from asthma are allergic to cockroaches,
dead or alive.
K-Selected Species
Saguaro
Elephant
Fewer, larger offspring
High parental care and protection of offspring
Later reproductive age
Most offspring survive to reproductive age
Larger adults
Adapted to stable climate and environmental conditions
Lower population growth rate (r)
Population size fairly stable and usually close to
carrying capacity (K)
Specialist niche
High ability to compete
Late successional species
The Giant Panda: Specialized and
Endangered
• Classic k-strategist =
specialist
• Feeds exclusively on
bamboo (1/3 of body
weight)
• Habitat fragmentation
has created “habitat
islands” of bamboo in
southwestern China
due to human
encroachment.
• 12 protected reserves
in China.
Why Are Panda Faced With
Extinction?
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Illegal poaching (pelt brings in $40,000-60,000).
Only one cub per female survives each year.
Gestation period = 22 months
Picky about mates. Find each other through
scent, become isolated due to habitat
fragmentation.
• Habitat islands interrupt natural migration to
adjacent areas when bamboo population
crashes in local areas.
• Approximately 700 panda left between zoos and
the wild.
Panda Babies
• Five giant panda cubs
were born in captivity in
2005: one at
Washington, D.C.'s
National Zoo and two
pairs of twins (one of
which is pictured above)
at China's Wolong
panda reserve.
• US pays 1 million/year
to China to have Mei
Xiang on exhibit for a
ten year period. All
offspring will be sent
back to China.
What Are Indicator Species?
• Indicator species serve as early warnings of
damage to a community.
• Birds and butterflies are migratory and are
excellent indicators of the environment. They do
not return to areas along their migratory routes
where deforestation has occurred or where
broad spectrum pesticides have been applied.
• Amphibians are also a universal indicator of
environmental degradation as they respire
through their skin.
Why Are Amphibians Vanishing?
• Appeared in the fossil record about 350
million years ago.
• Frogs and toads have been around for 150
million years (indicates adaptability)
• Last 20 years nearly 3,000 species of
frogs and toads have disappeared.
Reasons for Global Amphibian
Declines
• Global climate change (Costa Rican golden toads)
• Dehydration weakens amphibians, susceptible to fatal
diseases.
• Introduction of non-native predatory fish into aquatic
habitats.
• Pollution (air, water, soil)– respire through skin.
• Consume insects that take up pesticides
(bioacumulation/biomagnification).
• Eggs sensitive to increases in UV radiation – endocrine
blockers)
• Consumption of frog legs (delicacy).
• Loss of habitat.
Indicator Species
• As indicator species,
amphibians may be
sending us an
important message
about the health of
the global
environment.
• They don’t need us,
but we and other
species need them.
Golden toads – once prevalent in
Costa Rica’s cloud forest have
disappeared.
Indicator Species on Long Island
Why Should We Care About
Indicator Species?
• They give clues that the environmental health is
deteriorating in parts of the world such as habitat
loss and degradation, pollution, UV exposure,
and climate change.
• They provide ecological services (niche) in
biological communities. ie. Amphibians eat more
insects including mosquitoes than birds. They
provide a food source for higher trophic levels.
• Amphibians especially provide a storehouse of
pharmaceutical products waiting to be discivered
(economic goods and services).
What Are Keystone Species?
• A keystone species holds a community
together, when it disappears, so does the
biological community. Elimination of a
keystone species dramatically alters the
structure and function of a community.
American Alligator – a Keystone
Species
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Largest North
American reptile;
only humans are
their predator.
Hunted nearly to
extinction for
exotic meat, and
leather to make
shoes and
pocketbooks,
and for sport.
Ecological Niche of American
Alligator
• Dig gator holes that collect freshwater
during the dry season which serve as
refuges for aquatic life, and supply
freshwater and food for many animals.
Ecological Niche of American
Alligator
• Alligator nesting mounds serve as nesting
and feeding sites for herons and egrets
Ecological Niche of American
Alligator
• Alligator eat large numbers of predatory
gar fish and help maintain healthy
numbers of game fish such as bass and
bream.
Ecological Niche of American
Alligator
• As alligators
move from gator
holes to nesting
sites, they keep
areas of open
water free of
invading
vegetation. This
helps to maintain
healthy
ecosystems with
flowing water.
American Alligator Protection
• In 1967, the US
Government placed
the American alligator
on the Endangered
Species List, which
protected it from
hunting.
• By 1975, the
American alligator
populations
rebounded
successfully.
Status of the American Alligator.
• In 1977, the US Fish and Wildlife Service
(DOI), down-listed the American alligator
to a threatened species in Florida,
Louisiana, and Texas.
• Limited kills with a license are permitted.
Recreational lotteries are held in the
Florida Everglades each year by FWS.
• Alligator farms established to fulfill the
market for alligator goods.
Why Should We Protect keystone
Species?
• They play critical roles in the cross pollination of
angiosperms (bees, hummingbirds, bats).
• Top predator keystone species help regulate the
population numbers of other species.
• The loss of keystone species can lead to
population crashes and extinctions of other
species that depend on it for ecological services.
E.O. Wilson
• “The loss of a keystone species is like a
drill accidentally striking a power line. It
causes lights to go out all over”
The Good News Is…
• Conservation Efforts on the
rise –
• President Theodore
Roosevelt (1901-1909) “the
Golden Age of Conservation”
• 1903 he established the first
federal refuge at Pelican
Island off the east coast of
Florida to protect the
endangered brown pelican.
Roosevelt
• T. Roosevelt also tripled the size of the forest
reserves and transferred administration from
Department of the Interior (USDOI) to
Department of Agriculture (USDA.
• 1905, Congress created the US Forest Service
to manage and protect forest reserves.
Roosevelt appointed Gifford Pinchot as its first
chief.
• 1907, Roosevelt reserved 16 million acres of
land. Congress was trying to ban Executive
orders for forest reservation. Roosevelt did this
defiantly the day before Congress’ ban became
law!
Pinchot
• (1905) Pinchot pioneered
scientific management of
forest resources on public
lands, using the principles
of sustainable yield and
multiple use.
• This same year, the
Audubon Society was
founded to preserve the
nation’s bird species.
Conservation Split
• Conservationists became the “wiseuse movement” – and believed that all
public lands should be managed
“wisely” and scientifically to provide
needed goods and services for the
country.
• Preservationists lead by John Muir
(founder of Sierra Club) believed that
remaining wilderness areas on public
lands should be left untouched.
Preservationists
University of Idaho
Department of Philosophy
Environmental Philosophy
• Aldo Leopold –
began the
Wilderness Society in
1935.
• Leopold helped draft
the Wilderness Act of
1964 and lobbied
Congress for it’s
passage.
Wilderness Act of 1964
• Wilderness Act of 1964: directed the Secretary
of the Interior, within 10 years, to review every
roadless area of 5,000 or more acres and every
roadless island (regardless of size) within
National Wildlife Refuge and National Park
Systems and to recommend to the President the
suitability of each such area or island for
inclusion in the National Wilderness
Preservation System, with final decisions made
by Congress. The Secretary of Agriculture was
directed to study and recommend suitable areas
in the National Forest System.
US National Park Service
• 1912, Congress created the US
National Park Service.
• 1916, Congress passed the
National park System Organic Act
– declared that the parks were to
be maintained in a manner that
leaves them unimpaired for future
generations and established the
National Park Service (DOI).
• Stephen Mather was the first
Director of NPS. He began
establishing grand hotels and other
tourist facilities in parks with
spectacular scenery to encourage
tourism by allowing private
concessionaires to operate
facilities within the parks.
Long Island’s National Parks and
National Wildlife Refuges’
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Fire Island National Seashore
Floyd Bennett Field
Jamaica Bay
Wortheim
Amagansett
Oyster Bay (JFK Bird Sanctuary)
Lido Beach
Elizabeth Morton
Target Rock (Caumsett State
Park)
• Seatuck
• Conscience Point
Aldo Leopold
• “We abuse land because we regard it as a
commodity belonging to us. When we see
land as a community to which we belong,
we may begin to use it with love and
respect”