Biodiversity Defined
•
“Biodiversity is the total variety of life on
earth. It includes all genes, species and
ecosystems and the ecological processes
of which they are a part” (Convention on
Biodiversity, 1992)
Central Case: Saving the
Siberian tiger
• The largest cat in the world
• The Russian Far East
mountains house the last
remaining tigers
• Nearly became extinct due to
hunting, poaching and habitat
destruction
• International conservation
groups saved the species
from extinction
– Research, education, zoos,
and captive breeding
programs
Where is the biodiversity?
• Endemic species – restricted to a
small region
– isolated areas (islands, mountain ranges)
– product of unique habitat, climate features
Biodiversity hotspots - areas with a high
concentration of endemic species,
experiencing rapid habitat loss
Species diversity
• Species Diversity = the number or
variety of species in the world or in a
particular region
– Richness = the number of species
– Evenness or relative abundance = extent
to which numbers of individuals of different
species are equal or skewed
– Speciation generates new species and
adds to species richness
– Extinction reduces species richness
The taxonomy of species
• Taxonomists = scientists
who classify species
– Physical appearance and
genetics determines a
species
– Genera = related species
are grouped together
– Families = groups of
genera
• Every species has a twopart scientific name:
genus and species
Subspecies: the level below a
species
• Subspecies = populations of species that
occur in different areas and differ slightly from
each other
– Divergence stops short of separating the species
– Subspecies are denoted with a third part of the
scientific name
Bengal tiger =
Panthera tigris
tigris
Siberian tiger =
Panthera tigris
altaica
Genetic diversity
• Encompasses the differences in DNA
among individuals within species and
populations
• The raw material for adaptation to local
conditions
Genetic diversity
• Populations with higher genetic diversity
can survive
– They can cope with environmental change
• Populations with low genetic diversity
are vulnerable
– To environmental change
– Disease
– Inbreeding depression = genetically
similar parents mate and produce inferior
offspring
Ecosystem diversity
• Ecosystem diversity = the number and
variety of ecosystems
• Also encompasses differing
communities and habitats
• Rapid vegetation change and varying
landscapes within an ecosystem
promote higher levels of biodiversity
Some groups contain more
species than others
• Species are not evenly
distributed among
taxonomic groups
– Insects predominate over
all other life-forms
– 40% of all insects are
beetles
• Groups accumulate
species by
– Adaptive radiation
– Allopatric speciation
– Low rates of extinction
Insects outnumber all
other species
Measuring biodiversity is not
easy
• Out of the estimated 3 - 100 million species
on Earth, only 1.7 - 2 million species have
been successfully catalogued
• Very difficult to identify species
– Many remote spots on Earth remain unexplored
– Small organisms are easily overlooked
– Many species look identical until thoroughly
examined
• Entomologist Terry Erwin found 163 beetle
species specialized on one tree species
Biodiversity losses and species
extinction
• Extinction = occurs when the last member of
a species dies and the species ceases to
exist
• Extirpation = the disappearance of a
particular population from a given area, but
not the entire species globally
– Can lead to extinction
Extinction is a natural process
• Paleontologists estimate 99% of all species
that ever lived are now extinct
• Background rate of extinction = natural
extinctions for a variety of reasons
– 1 extinction per 1 to 10 million species for
mammals and marine species
– 1 species out of 1,000 mammal and marine
species would go extinct every 1,000 to 10,000
years
Earth has experienced five
mass extinctions
• In the past 440 million years, mass extinctions
have eliminated at least 50% of all species
• After every mass extinction the biodiversity
returned to or exceeded its original state
Current Status of Biodiversity
• 1.4 million described species, possibly
10 million in total
• Background extinction rate – rate of
species loss in the absence of human
activities
– fossil record: species survive 1-10 million
years
– one year: one species has a 1 in 1-10
million chance of going extinct
– total: 1 extinction per year
The current mass extinction is
human caused
• During this Quaternary period, we may
lose more than half of all species
– Hundreds of human-induced species
extinctions, and multitudes of others, teeter
on the brink of extinction
• The current global extinction rate is 100
to 1,000 times greater than the
background rate
– This rate will increase tenfold in future
decades due to human population growth
and resource consumption
People have hunted species to
extinction for millennia
Extinctions followed human arrival on islands and continents
Current extinction rates are
higher than normal
• The Red List = an updated list of species
facing high risks of extinctions
– 23% of mammal species
– 12% of bird species
– 31 - 86% of all other species
• Since 1970, 58 fish species, 9 bird species,
and 1 mammal species has gone extinct
– In the U.S., in the last 500 years, 236 animal and
17 plant species are confirmed extinct
– Actual numbers are undoubtedly higher
Biodiversity loss has many
causes
• Reasons for biodiversity losses are
multifaceted, complex, and hard to determine
– Factors may interact synergistically
• Four primary causes of population decline
are:
–
–
–
–
Habitat alteration
Invasive species
Pollution
Overharvesting
• Global climate change now is the fifth cause
Ecological interactions
Biodiversity is more than the sum of the
parts
Interactions “structure” communities, maintain
diversity, and make ecosystems work
e.g. Competition
Predation
Mutualisms (e.g. pollination, seed dispersal)
• Some estimates for current rate:
– 1 species per hour
– 1 million species total, so far
– 10% of all species so far
– 8.8% of all species
– 27,000 species per year
– 20% of neotropical plant species
– 100 to 10,000 times the background rate
• Numbers of threatened/endangered
species:
– 5,188 vertebrates (9%)
– 1,992 invertebrates (0.17%)
– 8,321 plants (2.89%)
– 2 lichens (0.02%)
• Since 1600, ~1000 species have gone
extinct (probably many more)
Why do species go extinct?
2 separate processes:
1. Something causes a large population
to decline.
2. Small populations go extinct.
Causes of species declines
1. Habitat destruction and fragmentation
2. Introduced species
3. Exploitation and overharvesting
4. Pollution
5. Climate change
Conservation biology
• Concerned with loss of biodiversity, not just
loss of species
– “Fundamental loss of resources in
genetics, species, community attributes
and ecosystem properties”
– Flip side: maintenance of biodiversity,
ecological and evolutionary processes
Why care about biodiversity?
• Intrinsic value (Muir, 1838-1914)
– All species have value independently of their
utility to humans
• Utilitarian value (Pinchot, 1865-1946)
– Species that provide the “greatest good to the
greatest number” (over the longest time)
have value
• Cons Bio : (Leopold, 1886-1948)
– can include both value systems
– “To keep every cog and wheel is the
first precaution of intelligent
tinkering" (Leopold 1943).
Aldo Leopold (1886-1948)
Evolutionary-Ecological Land Ethic
• Biological communities: assemblages
of interdependent species
• Maintaining the health of natural
ecosystems and ecological /
evolutionary processes
• Humans exist within the ecological
community; depend on ecosystem
services
• Synthetic approach:
– Both intrinsic value and utilitarian value
Why be concerned about biodiversity
loss if extinction is a fact of life?
Moderate certainty:
extinction
rates > by 100
– 1000 times
Is extinctioncurrent
outpacing
speciation
potential?
10 – 30 % of mammals, birds and amphibians
threatened
Major drivers of endangerment
From Wilcove 1996
What’s missing?
Threats to terrestrial species
• Terrestrial habitat loss
• 39-50% of land surface transformation
•
Habitat alteration causes
biodiversity
loss
The greatest cause of biodiversity loss
– Farming simplifies communities
– Grazing modifies the grassland structure and
species composition
– Clearing forests removes resources organisms
need
– Hydroelectric dams turn rivers into reservoirs
upstream
– Urbanization and suburban sprawl reduce natural
communities
– A few species (i.e., pigeons, rats) benefit from
changing habitats
Result of habitat loss
• Reduction in total area  decrease in
size, # of populations  local
extinctionsfewer species
• Reduction in habitat diversity
– Reduced species diversity
– Cascading effects, co-extinctions
Habitat alteration has
occurred in every biome
Particularly in tropical rainforests, savannas,
and tropical dry forests
The forested areas of Warwickshire, England
Habitat
fragmentation
• Above and
beyond habitat
loss
• Isolation: reduced
immigration, recolonization
• Edge effects
From Primack 2002
Invasion
HOMOGENIZATION
– The distribution of
species on Earth is
becoming more
homogenous
– The rate of invasion is
increasing over time
Growth in Number of Marine
Species Introductions in North
America and Europe
Introduced cheatgrass, Bromus tectorum,
has transformed the Great Basin shrubsteppe ecosystem
• Has increased
fire frequency
from once/80
years to once/4
years!
• Occupies over 5
million hectares
of Great Basin
Pollution causes biodiversity
loss
• Harms organisms in many ways
– Air pollution degrades forest ecosystems
– Water pollution adversely affects fish and
amphibians
– Agricultural runoff harms terrestrial and aquatic
species
– The effects of oil and chemical spills on wildlife are
dramatic and well known
• The damage to wildlife and ecosystems
caused by pollution can be severe
– But it tends to be less than the damage caused by
habitat alteration or invasive species
Climate change effects on
biodiversity
• Range shifts
Latitudinal range
Altitudinal range
• Mis-matched interactions
• Reassembled (scrambled) communities
• Feedbacks (e.g. vegetation and climate)
• Species Endangerment
Climate change causes
biodiversity loss
• Emissions of greenhouse gases warms
temperatures
– Modifies global weather patterns and
increases the frequency of extreme weather
events
– Increases stress on populations and forces
organisms to shift their geographic ranges
• Most animals and plants will not be able
to cope
Warming has been the greatest in
the Arctic
The polar bear is being considered for the
endangered species list
Climate change endangers polar bears
• Sea ice is the key
– Bottom up: habitat for
micro-algae
– Top down: seal
hunting ground;
corridors to dens
• Loss of sea ice 
endangers polar bear
• Loss of top predator:
cascading effects on
Arctic food web
Climate change can induce
coral reef bleaching
http://www.ogp.noaa.gov/misc/coral/98bleaching/
Bleached and normally pigmented Pocillopora colonies
Oceans and Freshwater Aquatic
habitats
• If anything are more vulnerable to same
threats, with enhanced vulnerability to
over-exploitation and pollution
• Freshwater
– USA: Very high endangerment levels in fish &
amphibians (25-40%) and crayfish & molluscs
(> 60%) compared to terrestrial vertebrates
(15-18%
Over-exploitation of global
ocean fisheries
• > 60% of the
world’s fisheries
are fully to over
exploited, or
depleted
• By-catch increases
fish-catch by 30%
Botsford 1997
Conserving biodiversity
• Genetic level: seed, egg, sperm banks
• Population and species level – science of
managing small populations
– Captive breeding (zoos/botanical gardens)
– Reintroductions
– Population management in the wild
• Protection (hunting, disease, habitat)
• Genetic management (translocations)
• Habitat restoration
Conserving biodiversity: habitat,
species, ecosystem level
• Protected areas
• Managing the matrix
– Restoration
– Wildlife-friendly agriculture
Protected areas for Biodiversity
Conservation
• Select the areas that represent and
maintain biodiversity over time…
(Margules and Pressey 2000)
REPRESENTATION
Including as many different
ecosystems and species in the
reserve network
Representing the full range of variation
(genetic, ecological) present within target
species
A network of reserves that
represents species efficiently
• But it may
not be so
good at
maintaining
biodiversity
– why not?
Site selection in the Sierra
Nevada foothills for
conservation prioritization
Maintaining biodiversity over time
• Population persistence (viability)
• Maintaining ecological processes
– E.g. migrations
• Maintaining evolutionary processes
– Potential for adaptation within populations
(genetic diversity)
– Selecting areas where rapid speciation is
occurring
• Response to climate change
Reserve design features for persistence
SIZE
Edge to area ratio
Shape
Environmental
gradients
Disturbance
regime
Corridors
Matrix habitat
CONNECTIVITY
Functional
units
SIZE
Larger size 
• More species (interactions, functions), S-A relationship
• More habitats (interactions, functions)
• Larger populations –
• Protects vulnerable species
– Area demanding: large-bodied, high-trophic level, rare
– Habitat specialists (if habitat included)
– Species requiring multiple habitat types
• Shape Reduced edge/area ratio, edge effects
• Disturbance regime: maintenance of disturbance-generated
patch heterogeneity
• Includes whole functional units
• Includes whole environmental gradients
SIZE & EDGE
EFFECTS
Edges create
core versus edge
habitat
Example: many
songbirds
experience high
nest predation
near edges in
woodlots within
sub-urban areas
From
Prim
Shape and
edge
effects
Meffe & Carroll 1997
DISTURBANCE REGIME
• Disturbance promotes habitat
heterogeneity
– By resetting successional sequence in
parts of the landscape
– Creating patchiness in the landscape
which is determined by the temporal and
spatial scale of the disturbance(s)
Spatial and temporal scale of disturbance varies by type
SIZE & DISTURBANCE REGIME
• Disturbance promotes habitat heterogeneity
– mosaic of patches at different successional stages
• Habitat heterogeneity:
– supports species requiring multiple habitat types
– Supports early successional species (e.g. Heath
fritillary butterfly = “Woodman’s follower”)
• Size of reserve  ideally as big as or bigger
than scale of likely disturbances
SIZE &
FUNCTIONAL
UNITS
Functionally interdependent
ecosystems:
e.g. “a complex,
dynamic patchwork
of mangroves, sea
grass bed and
reefs”
(Moberg &
Ronnback 2003)
Reserve design features for persistence
SIZE: Bigger is better!
Edge to area ratio
Shape
Environmental
gradients
Disturbance
regime
Corridors
Matrix habitat
CONNECTIVITY
Functional
units
CONNECTIVITY
• Isolation is a key factor causing loss of species
from reserves
– Preventing gene flow, maintenance of genetic diversity
– Reducing recolonization following extinction (rescue
effect)
– Preventing access between summer/winter grounds
for migratory species
– Preventing access to multiple habitat types needed for
different life stages
– Preventing response to global warming
Wildlife overpass
Transportation Equity Act for the 21st Century
provides funding
Managing the Matrix
Making matrix “friendly” to wildlife
---
Reserve zonation: core, buffer, transition
Wildlife friendly farming/Restoration
CONNECTIVITY:
Multi-scale responses
PROBLEM of FRAGMENTATION
RESPONSE
– Preventing gene flow, maintenance of genetic diversity
– Reducing recolonization following extinction (rescue effect)
•Create corridors between reserves
•Manage the matrix around reserves
– Preventing access between summer/winter grounds for migratory
species
Protect migratory routes/stop-overs
– Preventing access to multiple habitat types needed for different life
stages
– Preventing response to global warming
Stop-over sites along songbird
migration routes
• Neotropical birds
• Use radar to detect
nocturnal bird
movement
– Timed to get
departure events from
stopover points (20-40
min after sunset)
– Signal characteristics
http://www.njaudubon.org/Education/Oases/RadImages.html
Breeding
wintering
CONNECTIVITY:
Multi-scale responses
PROBLEM of FRAGMENTATION
RESPONSE
– Preventing gene flow, maintenance of genetic diversity
– Reducing recolonization following extinction (rescue effect)
•Create corridors between reserves
•Manage the matrix around reserves
– Preventing access between summer/winter grounds for migratory
species
Protect migratory routes/stop-overs
– Preventing access to multiple habitat types needed for different life
stages
•Include whole functional units, disturbance
regimes, environmental gradients within
reserves or reserve networks
– Preventing response to global warming
•Include elevational or latitudinal gradients
within reserves
Designing Masoala National Park, Madagascar
•Habitat heterogeneity –
connectedness between
habitats, marine and
terrestrial
•Species response to climate
change: Include elevational
gradients within reserve
Masoala, Madagascar
New Reserve Design Methods
• Represent species
or habitats
efficiently
• Minimize edge
effects, maximize
clustering
• Maximize
connectivity
Leslie et al. 2003 Ecol App.
Biodiversity provides free
ecosystem services
• Provides food, shelter, fuel
• Purifies air and water, and detoxifies wastes
• Stabilizes climate, moderates floods, droughts, wind,
temperature
• Generates and renews soil fertility and cycles
nutrients
• Pollinates plants and controls pests and disease
• Maintains genetic resources
• Provides cultural and aesthetic benefits
• Allows us to adapt to change
The annual value of just 17 ecosystem services = $16 - 54 trillion per
year
Biodiversity helps maintain
ecosystem function
• Biodiversity increases the stability and resilience of
communities and ecosystems
– Decreased biodiversity reduces a natural system’s ability to
function and provide services to our society
• The loss of a species affects ecosystems differently
– If the species can be functionally replaced by others, it may
make little difference
– Extinction of a keystone species may cause other species to
decline or disappear
• “To keep every cog and wheel is the first precaution of
intelligent tinkering” (Aldo Leopold)
Biodiversity enhances food
security
• Genetic diversity within crops is enormously
valuable
– Turkey’s wheat crops received $50 billion worth of
disease resistance from wild wheat
• Wild strains provide disease resistance and
have the ability to grow back year after year
without being replanted
• New potential food crops are waiting to be
used
– Serendipity berry produces a sweetener 3,000
times sweeter than sugar
Organisms provide drugs and
medicines
• Each year
pharmaceutical
products owing their
origin to wild
species generate up
to $150 billion in
sales
– The rosy periwinkle
produces
compounds that treat
Hodgkin's disease
and leukemia
Biodiversity generates
economic benefits
• People like to experience protected natural
areas, creating economic opportunities for
residents, particularly in developing countries
– Costa Rica: rainforests
– Australia: Great Barrier Reef
– Belize: reefs, caves, and rainforests
• A powerful incentive to preserve natural
areas and reduce impacts on the landscape
and on native species
• But, too many visitors to natural areas can
degrade the outdoor experience and disturb
wildlife
Do we have ethical obligations
to other species?
• Humans are part of nature and need
resources to survive
• But, we also have conscious reasoning ability
and can control our actions
– Our ethics have developed from our intelligence
and our ability to make choices
• Many people feel that other organisms have
intrinsic value and an inherent right to exist
Conservation scientists work at
multiple levels
• Conservation biologists integrate evolution and extinction
with ecology and environmental systems
– Design, test, and implement ways to mitigate human impacts
• Conservation geneticists = study genetic attributes of
organisms to infer the status of their population
• Minimum viable population = how small a population
can become before it runs into problems
• Metapopulations = a network of subpopulations
– Small populations are most vulnerable to extinction and need
special attention
Island biogeography
• Equilibrium theory of island biogeography
= explains how species come to be
distributed among oceanic islands
– Also applies to “habitat islands” – patches of one
habitat type isolated within a “sea” of others
– Explains how the number of species on an island
results from an equilibrium between immigration
and extirpation
– Predicts an island’s species richness based on
the island’s size and distance from the mainland
Species richness results from
island size and distance
• Fewer species colonize an island far from the mainland
• Large islands have higher immigration rates
• Large islands have lower extinction rates
The species-area curve
• Large islands contain more species than small
islands
– They are easier to find and have lower extinction rates
– They possess more habitats
Small “islands” of forest rapidly
lose species
• Forests are fragmented by
roads and logging
• Small forest fragments lose
diversity fastest
– Starting with large species
• Fragmentation is one of the
prime threats to biodiversity
Should conservation focus on
endangered species?
• Endangered Species Act (1973) (ESA) =
forbids the government and private citizens
from taking actions that destroy endangered
species or their habitats
– To prevent extinction
– Stabilize declining populations
– Enable populations to recover
• As of 2007, the U.S. had 1,312 species listed
as endangered or threatened
Despite opposition, the ESA
has
had
successes
• Peregrine falcons, brown pelicans, bald
eagles, and others have recovered and are
no longer listed
• Intensive management has stabilized other
species
– The red-cockaded woodpecker
– 40% of declining populations are now stable
• These successes occur despite underfunding
of the U.S. Fish and Wildlife Service and the
National Marine Fisheries Service
– In recent years, political forces have attempted to
weaken the ESA
The ESA is controversial
• Many Americans support protection of
endangered species
• Opponents feel that the ESA values endangered
organisms more than the livelihood of people
– Private land use will be restricted if an endangered
species is present
– “Shoot, shovel, and shut up” = landowners conceal
the presence of endangered species on their land
• But, the ESA has stopped few development projects
– Habitat conservation plans and safe harbor agreements =
landowners can harm species if they improve habitat for the
species in other places
Other countries have their own
version of the ESA
• Species at Risk Act (2002) = Canada’s
endangered species law
– Stresses cooperation between landowners and
provincial governments
– Criticized as being too weak
• Other nations’ laws are not enforced
– The Wildlife Conservation Society has to help pay
for Russians to enforce their own anti-poaching
laws
Protecting biodiversity
• Captive breeding – individuals are bred and
raised with the intent of reintroducing them into
the wild
– Zoos and botanical gardens
• Some reintroductions are controversial
– Ranchers opposed the reintroduction of wolves to
Yellowstone National Park
– Some habitat is so fragmented, a species cannot
survive
Protecting biodiversity
• Cloning – a technique to create more
individuals and save species from extinction
– Most biologists agree that these efforts are not
adequate to recreate the lost biodiversity
• Ample habitat and protection in the wild are
needed to save species
Umbrella species
• Conservation biologists use particular species as tools
to conserve communities and ecosystems
– Protecting the habitat of these umbrella species
helps protect less-charismatic animals that would not
have generated public interest
• Flagship species – large and charismatic species used
as spearheads for biodiversity conservation
– The World Wildlife Fund’s panda bear
• Some organizations are moving beyond the single
species approach to focus on whole landscapes
International conservation
efforts
• UN Convention on International Trade in
Endangered Species of Wild Fauna and Flora
(1973) (CITES) – protects endangered species
by banning international transport of their body
parts
• Convention on Biological Diversity (1992) –
– Seeks to conserve biodiversity
– Use biodiversity in a sustainable manner
– Ensure the fair distribution of biodiversity’s
benefits
– By 2007, 188 nations had signed on
– Iraq, Somalia, the Vatican, and the U.S. did
not join
Community- based conservation
• Protecting habitats makes good sense, but
this affects people living in and near these
areas
• Community-based conservation =
conservation biologists actively engage
local people in protecting land and wildlife
– Protecting land deprives people access to
resources
– But, it can guarantee that these resources will
not be used up or sold to foreign corporations
and can instead be sustainably managed
• Many projects have succeeded
– But, others have not, due mainly to funding
Innovative economic strategies
• Debt-for-nature swap = a conservation
organization pays off a portion of a
developing country’s international debt
– In exchange for a promise by the country to
set aside reserves
– Fund environmental education, and
– Better manage protected areas
• Conservation concession = conservation
organizations pay nations to conserve,
and not sell, resources
Conclusions
• Biodiversity has great value, both
intrinsically, and also because human life
depends on it
• But, it is under threat, from habitat loss
and degradation, invasive species, climate
change, pollution and over-exploitation
• Conservation biologists have many tools
to protect biological diversity, from genetic
to ecosystem levels.
Conclusions
• Protected areas are an important tool for
biodiversity conservation.
• The design of protected areas and reserve
networks should foster representation of
biodiversity and its persistence.
– Reserves need to be sited efficiently to
represent biodiversity.
– Size, shape and connectivity of reserves and
relationship with the surrounding landscape
matrix are essential considerations for
biodiversity persistence.