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Biodiversity
What is Biodiversity?
Biological Diversity or Biodiversity
“The variety of life in all
its forms, levels and
combinations. Includes
ecosystem diversity,
species diversity, and
genetic diversity”
(IUCN, UNEP and
WWF, 1991).
Biodiversity
• Biodiversity
is currently
declining
• Species
are going
extinct
Extinction
Extinction is a
natural process
~ 99% of all
species have
become extinct
Extinction
Natural Extinction
• Typically occurs at slow pace
A few species disappearing
over long time periods
Extinction
Natural Extinction
• though there
have been
rapid, mass
extinctions
Extinction
Accelerated Extinction
• Occurring at a rapid pace
Many species are
disappearing every year
Extinction
Natural Extinction
• Often old species evolve into
new species over time
Extinction
Natural
Extinction
• Offspring species
survive and
continue to evolve
Extinction
Accelerated Extinction
Species are disappearing too
rapidly to evolve into new species
No evolutionary or
genetic legacy remains
Extinction
We are currently experiencing the
greatest extinction event of the
last 65 million years – since the
disappearance of the dinosaurs
Peter Raven
Biodiversity
How many species have
been identified ?
Approximately 1.4 million species
have been named and described
Biodiversity
•
•
•
•
•
Vertebrates
Insects 750,000
Mammals 4,000
Birds 9,000
Reptiles 6,300
Amphibians 4,200
Fish 19,000
Plants 250,000
Non-insect
arthropods 125,000
Other species
200,000
Biodiversity
How many species have
been thoroughly studied ?
Only 1 - 2 %
We have done little more than name
most of the species that we know about
Biodiversity
How many species are
currently alive on Earth ?
We do not know !
Biodiversity
How many species are
currently alive on Earth ?
In the past, estimates
were 3 –5 million species
Biodiversity
How many species are
currently alive on Earth ?
Recent estimates are more
than 10 million species
Biodiversity
How many species are
currently alive on Earth ?
The higher numbers of more recent
estimates are due to recognition of vast,
unknown biodiversity in tropical
rainforests
Biodiversity
How many species are
currently alive on Earth ?
Many species will disappear
before we can even identify and
name them
Biodiversity
What is the primary cause of
the current high rates of
extinction of species ?
Habitat Alteration
Habitat Alteration
• The most significant single
factor in extinctions
• Habitats are destroyed as human
societies alter ecosystems
Habitat Alteration
• Rainforest destruction
threatens countless species
Habitat Alteration
• Human activities have
significantly altered an
estimated 50-75% of the
ice-free land surface of the
Earth
Habitat Alteration
• Will Global Climate Change be the
greatest habitat alteration of all?
According to the IPCC, a
warming of 1.5 – 2.5 0C would
place 20 - 30% of species at
increased risk of extinction
Habitat Alteration
• Will Global Climate Change be the
greatest habitat alteration of all?
According to the IPCC, a
warming above 3.5 0C would place
40 - 70% of species at increased
risk of extinction
Human Pressures on Species
•Habitat Alteration
- most important by far -
Other pressures include:
• Commercial Hunting and Poaching
• Introduction of Alien Species
• Pest and Predator Control
Human Pressures on Species
• Commercial hunting and fishing
have resulted in decline of whales,
sea turtles, and other species
Human Pressures on Species
• Poaching threatens elephants,
rhinos and other species
Human Pressures on Species
• Introduction of alien species and
diseases often threatens native species
Human Pressures on Species
• Efforts to control pests and predators
can harm species and ecosystems
Vulnerability of Species
Ecological factors make some species
more vulnerable to extinction
• Critical population size
• Limited geographic range
• Dietary specialists
• Larger size species
• Tolerance to human presence
Vulnerability of Species
Critical population size
• Once a population falls to a
small number, particularly a
social species, the population may
not be able to recover
Vulnerability of Species
Limited geographic range
• Species with a small geographic
range are more vulnerable to
extinction than are geographically
widespread species
Vulnerability of Species
Dietary specialists
• Species with highly specialized
diets are more vulnerable to
extinction than are dietary
generalists
Vulnerability of Species
Larger size species
• Larger species more directly
compete with humans
• Larger species tend to have lower
reproductive rates
Vulnerability of Species
Tolerance to human presence
• Some species do not tolerate
human presence and will not inhabit
areas where humans are found
Reasons for Concern
Biodiversity is Rapidly
Declining
Why should we care
and be concerned ?
Reasons for Concern
Ethics
• We have the power to
destroy or save species
• It is wrong for us to destroy other species
• It is right for us to save other species
Reasons for Concern
Aesthetics
•
The diversity of species gives
beauty to our world and the
experiences of life
Reasons for Concern
Economics
• A tremendous portion of our
economy depends on biological species
• Species extinctions deny us
potential economic opportunities
Reasons for Concern
New Medicines
• Many of our medicines are based
upon biological species
• Species extinctions deny us
potential new medicines
Reasons for Concern
New Foods
• All of our foods are based on
biological species
• Species extinctions deny us
potential new foods
Reasons for Concern
Ecosystem Stability
• Complex ecosystems with greater
species diversity are more stable over time
• Species extinctions makes ecosystems
less complex and less stable
Reasons for Concern
Future Generations
• We must preserve the biological
wealth of the Earth for the sake of
our children, grandchildren, and
countless future generations