biodiversity bs 105 fall 2007 bw - southeast...

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BiodiversityBiodiversity What is Biodiversity?What is Biodiversity?Biological Diversity or Biological Diversity or BiodiversityBiodiversity

““The variety of life in all The variety of life in all its forms, levels and its forms, levels and combinations. Includes combinations. Includes ecosystem diversity, ecosystem diversity, species diversity, and species diversity, and genetic diversity” genetic diversity” (IUCN, UNEP and (IUCN, UNEP and WWF, 1991).WWF, 1991).

BiodiversityBiodiversity• Biodiversity

is currently declining

• Species are going extinct

ExtinctionExtinctionExtinction is a Extinction is a natural processnatural process

~ 99% of all ~ 99% of all species have species have

become extinctbecome extinct

ExtinctionExtinctionNatural ExtinctionNatural Extinction

• Typically occurs at slow paceTypically occurs at slow pace

A few species disappearing A few species disappearing over long time periodsover long time periods


•• though there though there have been have been

rapid, mass rapid, mass extinctionsextinctions

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Accelerated ExtinctionAccelerated Extinction

ExtinctionExtinction

• Occurring at a rapid paceOccurring at a rapid pace

Many species are Many species are disappearing every yeardisappearing every year


• Often old species evolve into Often old species evolve into new species over timenew species over time

ExtinctionExtinctionNatural Natural

ExtinctionExtinction

• Offspring species Offspring species survive and survive and

continue to evolvecontinue to evolve

Accelerated ExtinctionAccelerated ExtinctionExtinctionExtinction

Species are disappearing too Species are disappearing too rapidly to evolve into new speciesrapidly to evolve into new species

No evolutionary or No evolutionary or genetic legacy remainsgenetic legacy remains

We are currently experiencing the We are currently experiencing the greatest extinction event of the greatest extinction event of the last 65 million years last 65 million years –– since the since the disappearance of the dinosaursdisappearance of the dinosaurs

Peter RavenPeter Raven

ExtinctionExtinction BiodiversityBiodiversityHow many species have How many species have

been identified ?been identified ?

Approximately 1.4 million species Approximately 1.4 million species have been named and describedhave been named and described

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VertebratesVertebrates•• Mammals 4,000Mammals 4,000•• Birds 9,000Birds 9,000•• Reptiles 6,300Reptiles 6,300•• Amphibians 4,200Amphibians 4,200•• Fish 19,000Fish 19,000

BiodiversityBiodiversityInsects 750,000Insects 750,000

Plants 250,000Plants 250,000NonNon--insect insect arthropodsarthropods 125,000125,000

Other species Other species 200,000200,000

How many species have How many species have been thoroughly studied ?been thoroughly studied ?

BiodiversityBiodiversity

Only 1 Only 1 -- 2 %2 %We have done little more than name We have done little more than name

most of the species that we know aboutmost of the species that we know about

How many species are How many species are currently alive on Earth ?currently alive on Earth ?


We do not know !We do not know !



In the past, estimates In the past, estimates were 3 were 3 ––5 million species5 million species



Recent estimates are more Recent estimates are more than 10 million speciesthan 10 million species



The higher numbers of more recent estimates are due to recognition of vast,

unknown biodiversity in tropical rainforests

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Many species will disappear Many species will disappear before we can even identify and before we can even identify and

name themname them

What is the primary cause of What is the primary cause of the current high rates of the current high rates of extinction of species ?extinction of species ?


Habitat AlterationHabitat Alteration

Habitat AlterationHabitat Alteration•• The most significant single The most significant single

factor in extinctionsfactor in extinctions

• Habitats are destroyed as human Habitats are destroyed as human societies alter ecosystemssocieties alter ecosystems

Habitat AlterationHabitat Alteration•• Rainforest destruction Rainforest destruction

threatens countless speciesthreatens countless species •• Human activities have Human activities have significantly altered an significantly altered an

estimated 50estimated 50--75% of the 75% of the iceice--free land surface of the free land surface of the

EarthEarth

Habitat AlterationHabitat Alteration•• Will Global Climate Change be the Will Global Climate Change be the

greatest habitat alteration of all?greatest habitat alteration of all?

Habitat AlterationHabitat Alteration

According to the IPCC, a According to the IPCC, a warming of 1.5 warming of 1.5 –– 2.5 2.5 00C would C would

place 20 place 20 -- 30% of species at 30% of species at increased risk of extinctionincreased risk of extinction

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Habitat AlterationHabitat Alteration•• Will Global Climate Change be the Will Global Climate Change be the

greatest habitat alteration of all?greatest habitat alteration of all?

According to the IPCC, a According to the IPCC, a warming above 3.5 warming above 3.5 00C would place C would place

40 40 -- 70% of species at increased 70% of species at increased risk of extinctionrisk of extinction

Human Pressures on SpeciesHuman Pressures on Species••Habitat AlterationHabitat Alteration

-- most important by far most important by far --

•• Commercial Hunting and PoachingCommercial Hunting and Poaching•• Introduction of Alien SpeciesIntroduction of Alien Species

•• Pest and Predator ControlPest and Predator Control

Other pressures include:Other pressures include:

•• Commercial hunting and fishing Commercial hunting and fishing have resulted in decline of whales, have resulted in decline of whales,

sea turtles, and other speciessea turtles, and other species

Human Pressures on SpeciesHuman Pressures on Species

•• Poaching threatens elephants, Poaching threatens elephants, rhinos and other speciesrhinos and other species

Human Pressures on SpeciesHuman Pressures on Species•• Introduction of alien species and Introduction of alien species and

diseases often threatens native speciesdiseases often threatens native species

Human Pressures on SpeciesHuman Pressures on Species•• Efforts to control pests and predators Efforts to control pests and predators

can harm species and ecosystemscan harm species and ecosystems

Human Pressures on SpeciesHuman Pressures on Species

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Vulnerability of SpeciesVulnerability of SpeciesEcological factors make some species Ecological factors make some species

more vulnerable to extinctionmore vulnerable to extinction• Critical population sizeCritical population size

•• Dietary specialistsDietary specialists•• Limited geographic rangeLimited geographic range

•• Larger size speciesLarger size species

•• Tolerance to human presenceTolerance to human presence

Vulnerability of SpeciesVulnerability of Species

Critical population sizeCritical population size

•• Once a population falls to a Once a population falls to a small number, particularly a small number, particularly a

social species, the population may social species, the population may not be able to recovernot be able to recover

Limited geographic rangeLimited geographic range


•• Species with a small geographic Species with a small geographic range are more vulnerable to range are more vulnerable to

extinction than are geographically extinction than are geographically widespread specieswidespread species

Dietary specialistsDietary specialists


• Species with highly specialized Species with highly specialized diets are more vulnerable to diets are more vulnerable to extinction than are dietary extinction than are dietary

generalistsgeneralists

Larger size speciesLarger size species


•• Larger species more directly Larger species more directly compete with humanscompete with humans

•• Larger species tend to have lower Larger species tend to have lower reproductive ratesreproductive rates

Tolerance to human presenceTolerance to human presence


•• Some species do not tolerate Some species do not tolerate human presence and will not inhabit human presence and will not inhabit

areas where humans are foundareas where humans are found

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Reasons for ConcernReasons for ConcernBiodiversity is Rapidly Biodiversity is Rapidly

DecliningDeclining

Why should we care and be concerned ?

Reasons for ConcernReasons for ConcernEthicsEthics

•• We have the power to We have the power to destroy or save speciesdestroy or save species

• It is wrong for us to destroy other species

• It is right for us to save other species

Reasons for ConcernReasons for Concern

AestheticsAesthetics• The diversity of species gives

beauty to our world and the experiences of life

Reasons for ConcernReasons for ConcernEconomicsEconomics

• A tremendous portion of our A tremendous portion of our economy depends on biological specieseconomy depends on biological species

•• Species extinctions deny us Species extinctions deny us potential economic opportunitiespotential economic opportunities

Reasons for ConcernReasons for ConcernNew MedicinesNew Medicines

•• Many of our medicines are based Many of our medicines are based upon biological speciesupon biological species

•• Species extinctions deny us Species extinctions deny us potential new medicinespotential new medicines


New FoodsNew Foods•• All of our foods are based on All of our foods are based on

biological speciesbiological species

•• Species extinctions deny us Species extinctions deny us potential new foodspotential new foods

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Reasons for ConcernReasons for ConcernEcosystem StabilityEcosystem Stability

•• Complex ecosystems with greater Complex ecosystems with greater species diversity are more stable over timespecies diversity are more stable over time

• Species extinctions makes ecosystems Species extinctions makes ecosystems less complex and less stableless complex and less stable


Future GenerationsFuture Generations•• We must preserve the biological We must preserve the biological wealth of the Earth for the sake of wealth of the Earth for the sake of our children, grandchildren, and our children, grandchildren, and

countless future generationscountless future generations

biodiversity bs 105 fall 2007 bw - southeast...

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