Biodiversity
•Three levels of Biodiversity
•How many species are there?
•What are the values of biodiversity?
•What threatens biodiversity?
•How do we protect biodiversity?
•How do biologists estimate extinction rates?
•How do humans affect extinction rates?
What is Biodiversity?
Three Levels:
•Genetic Diversity- variety of different versions of the
same genes within a species
•Species Diversity- number of different kinds of
organisms within a community or ecosystem
•Ecological Diversity- richness and complexity of
biological community (number of niches, trophic levels,
ecological processes)
How many Species Exist?
• Nobody knows for suremillions still need to be
studied
• 1.7 million presently
known
• Estimates of actual
number range from 1050 million
• Most in the tropics (hot
spots)
Why are so many species
unidentified and unstudied?
• Biologists know most about large species
– Smaller groups poorly studied
• Biodiversity concentrated in tropics but most
fieldwork concentrated in temperate
regions
• Biggest need is study of insects in tropical
areas!
What are the values of Biodiversity?
Why do we care if it disappears?
• Ecosystems and the species living in them
have enormous economic value to humans
– $33 trillion per year
• This is known as Earth’s biological wealth
• Wild species have many types of values
besides dollar values
Two Major Types of Species Value
• Instrumental Value
• Existence or use
benefits another
entity
• Also called
anthropocentric
value
• Intrinsic Value
• Has value for its own
sake
• Does not have to be
useful to have value
• Arguments for
intrinsic value in
different religions
• If all species created by God then all
have value
• We (humans) are in charge of God’s
creation; it’s not here just for us but for
him
• Similar ideas found in Judaism, Islam
Values of Biodiversity:
Food & Agriculture
•Ecologists estimate that
up to 80,000 edible wild
plants could be used by
humans
•Also may be useful as
genetic material to
improve domestic crops
Values of Biodiversity:
Drugs and Medicines
•More than half of all
prescriptions contain some
natural ingredients
•Value of these products is
$30 billion per year
•Indigenous people are rarely
acknowledge or
compensated for these
products
• Success stories include rosy periwinkle
from Madagascar- used to make cancer
drugs that treat childhood leukemia
and Hodgkin’s disease
• Many medicinal plants yet to be
discovered
Nature’s Pharmacy
Nature’s Pharmacy
Rauvolfia
Rauvolfia sepentina,
Southeast Asia
Tranquilizer, high
blood pressure
medication
Nature’s Pharmacy
Foxglove
Digitalis purpurea,
Europe
Digitalis for heart failure
Nature’s Pharmacy
Pacific yew
Taxus brevifolia,
Pacific Northwest
Ovarian cancer
Nature’s Pharmacy
Cinchona
Cinchona
ledogeriana
South America
Quinine for malaria
treatment
Nature’s Pharmacy
Rosy periwinkle
Cathranthus roseus,
Madagascar
Hodgkin's disease,
lymphocytic leukemia
Nature’s Pharmacy
Neem tree
Azadirachta indica,
India
Treatment of many
diseases, insecticide,
spermicide
Values of Biodiversity:
Ecological Benefits
•Organisms perform many services in their ecosystems:
•Soil formation
•Waste disposal
•Air and water purification
•Nutrient cycling
•Pest control
•Spaceship Earth- every species is a rivet…we don’t know
which one will make the whole ship fall apart
Values of Biodiversity:
Aesthetic and Cultural Benefits
•Outdoor Activities
•Psychological and
Emotional wellbeing
•Spiritual
•Economic Value
• Ecotourism is a
growing industry
• Species can have
value if they are
beautiful, aweinspiring
What Threatens Biodiversity?
Natural Causes
•99% of all species that ever existed have
gone extinct
•Mass extinctions have wiped out vast numbers of
species many times before
•Current rate of extinction is fastest it has ever
been (1000-10,000x higher than natural rate)
How Bad is It?
• 12,259 species known by IUCN (World
Conservation Organization) to be
threatened with extinction
• Sample of 47 common farmland and
woodland birds monitored in 18 European
countries show 71% decline from 19802002
• Two best-monitored groups of world’s
animals are mammals and birds
• Every 4th mammal (24%) and every 8th bird
(12%) facing high risk of extinction
• Across European continent
– 42% of mammals threatened
– 15% of birds threatened
– 45% of butterflies, 30% of amphibians, 45% of
reptiles, 52% of freshwater fish threatened
Percentages of Various Types of Organisms
Threatened with Extinction by Human Activities
34% (51% of
freshwater species)
Fish
24%
Mammals
20%
Reptiles
Plants
Birds
14%
12%
Fig. 9-5, p. 188
Types of Species Extinction

Local extinction

Ecological extinction

Biological extinction
Some Prematurely Extinct Species
Passenger
pigeon
Great auk
Dodo
Dusky seaside
sparrow
Aepyornis
(Madagascar)
Fig. 9-2, p. 185
Endangered and
Threatened
Species

Endangered speciesin immediate danger
of extinction over all
or part of their range

Threatened speciesnot in danger yet but
vulnerable to
becoming
endangered
Endangered and Threatened Species
Grizzly bear
(threatened)
Mojave desert
tortoise (threatened)
Kirtland's warbler White top
pitcher plant
Swallowtail
butterfly
Humpback chub
Arabian oryx
(Middle East)
Golden lion
tamarin (Brazil)
African elephant
(Africa)
Siberian tiger
(Siberia)
Endangered and Threatened Species
West Virginia
spring salamander
Mountain gorilla
(Africa)
Giant panda
(China)
Pine barrens
tree frog (male)
Whooping crane Knowlton cactus
Swamp pink
Hawksbill sea
turtle
Blue whale
El Segundo blue
butterfly
More Endangered and Threatened Species
Florida
manatee
Devil's hole
pupfish
Ghost bat
(Australia)
Northern spotted
owl (threatened)
Snow leopard
(Central Asia)
Gray wolf
Florida panther
Symphonia
(Madagascar)
Black-footed
ferret
California condor Black lace cactus Black rhinoceros
(Africa)
Bannerman's
turaco (Africa)
Utah prairie dog
(threatened)
Oahu tree snail
Characteristics of Extinction-prone
Species
Characteristic
Examples
Low reproductive rate
(K-strategist)
Blue whale, giant panda,
rhinoceros
Specialized niche
Blue whale, giant panda,
Everglades kite
Narrow distribution
Many island species,
elephant seal, desert pupfish
Feeds at high trophic
level
Bengal tiger, bald eagle,
grizzly bear
Fixed migratory patterns
Blue whale, whooping crane,
sea turtles
Rare
Many island species,
African violet, some orchids
Commercially valuable
Snow leopard, tiger,
elephant, rhinoceros,
rare plants and birds
Large territories
California condor, grizzly
bear, Florida panther
Problems Estimating
Extinction Rates

Extinction not easily documented over time

Many species remain unidentified

Little is known about most identified species
Estimating Extinction Rates

Estimates from records and fossils

Species-area relationship

Models to estimate risks of extinction for a
particular species

Estimates of extinction rates can vary
depending on available data and what
assumptions are used
Causes of Premature Extinction

“HIPPO”

Habitat destruction and fragmentation

Invasive (alien) species

Population growth (humans)

Pollution

Overharvesting
Causes of Premature Extinction
Habitat
loss
Overfishing
Pollution
Habitat degradation
and fragmentation
Climate change
Commercial
hunting and poaching
Introducing
nonnative species
Predator and pest control
Sale of exotic pets
and decorative plants
Secondary Causes
•Population growth
•Rising resource use
•No environmental
accounting
•Poverty
Basic Causes
Fig. 9-7, p. 190
What Threatens Biodiversity?
Habitat Destruction
•Number one reason for
the current increase in
extinctions
•Habitats most in danger
include tropical and
temperate forests,
wetlands, and prairies
Spotted Owl
Reduced Ranges
Indian Tiger
Range 100 years ago
Range today
(about 2,300 left)
Fig. 9-8a, p. 191
Reduced Ranges
Black Rhino
Range in 1700
Range today
(about 2,400 left)
Fig. 9-8b, p. 191
Reduced Ranges
African Elephant
Probable range 1600
Range today
Fig. 9-8c, p. 191
Reduced Ranges
Asian or Indian Elephant
Former range
Range today
(34,000–54,000 left)
Fig. 9-8d, p. 191
What Threatens Biodiversity?
Habitat Fragmentation
• Reduction of habitat into
smaller, more scattered
patches
• Many species need large
territories to exist
• Divides population into small,
vulnerable groups
• Causes edge effect
• Related to island
biogeography
What about World’s Ecosystems?
• World’s forests house almost ½ global biodiversity
• They are disappearing at rate of 0.8% per year
• Estimated 80% of original forest that covered Earth has
been cleared, damaged, or fragmented
• Tropical forests vanishing at 4% per year
• U.S. has lost more than 90% of its once species-rich
wetlands
• 1/3 of world’s coral reefs already gone, another 1/3
under threat
What Threatens Biodiversity?
Hunting and Fishing
•Overharvesting is responsible for
the depletion or extinction of
many species
•Examples include passenger
pigeon, bison, whales
•Overfishing continues to
threaten many species
Bison (above)
and dodo (right)
John James Audubon on
the Passenger Pigeon:
“The air was literally filled with pigeons; the
light of noon-day was obscured as by an
eclipse, the dung fell in spots, not unlike
melting flakes of snow; and the
continued buzz of wings had a tendency
to lull my senses to repose…Before sunset
I reached Louisville, distance from
Hardensburgh 55 miles. The pigeons
were still passing in undiminished
numbers, and continued to do so for
three days in succession.”
What Threatens Biodiversity?
Commercial Products and Live Specimens
•Includes both live specimens
(pet trade) and parts of species
•Powdered rhino horn sells for
$28,000 per kg
Endangered Black Rhino
•Other examples are tigers,
elephants, tropical fish and
birds, plants such as wild
ginseng
Confiscated Products From
Endangered Species
Fig. 9-18, p. 199
What Threatens Biodiversity?
Predator and Pest Control / Invasive Spp.
•Animals can be harmed because they are considered pests, or
because they are victims of another pest control effort
•Examples include prairie dogs, coyotes, bobcats
•Invasive species (more than 4500 in the U.S.) include:
•Zebra mussels
•Purple loosestrife
•Asian long-horned beetle
•Kudzu
•Round goby
Deliberately Introduced Species
Purple looselife
European starling
Marine toad
Water hyacinth
African honeybee
(“Killer bee”)
Japanese beetle
Nutria
Hydrilla
Salt cedar
(Tamarisk)
European wild boar
(Feral pig)
Accidentally Introduced Species
Sea lamprey
(attached to lake trout)
Formosan termite
Argentina fire ant
Zebra mussel
Brown tree snake
Asian long-horned
beetle
Eurasian muffle
Common pigeon
(Rock dove)
Asian tiger mosquito
Gypsy moth larvae
Kudzu
Fire Ant Invasion
1918
2000
Reducing Threats from
Nonnative Species

Prevention is best

Identify the characteristics of nonnative species

Identify vulnerable ecosystems

Thoroughly inspect imports

Establish appropriate international laws

Discharge of ballast waters from ships
What Threatens Biodiversity?
Diseases
•Examples include chestnut blight and distemper in black-footed
ferret
•When a new disease is introduced it may throw off the balance of
the whole system
Pollution
•Often a greater threat in higher trophic levels because of
bioaccumulation (marine mammals, birds of prey)
•Common pollutants include pesticides and other toxic chemicals,
and lead
Biomagnification of DDT
DDT in fish-eating
birds (ospreys)
25 ppm
DDT in large
fish (needle fish)
2 ppm
DDT in small
fish (minnows)
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm,
or 3 ppt
Fig. 9-16, p. 1
Litter Kills Seals
Fig. 9-19, p. 200
What Threatens Biodiversity?
Genetic Assimilation
•Rare species can
become even more rare
when they crossbreed
with other species that
are more numerous and
more hearty.
•Examples are wolves,
trout, and salmon