The Loss of Biodiversity
ESC 556 Week 9
Causes and Consequences
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Prominent species & causes
◦ Endangered Species
◦ Overexploitation by humans
Causes and Consequences
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Obscure species & causes
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Habitat destruction
Plants & insects
Loss of free services
Loss of genetic diversity
Habitat Destruction
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Thousands threatened vs. a few overexploited
◦ Plowing, logging, overgrazing, flooding, draining….
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Dependence on habitats
◦ Birds  mature tropical forests
◦ Bats  caves
◦ Trout  Can’t breed in acidic or too warm water
Human impact
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NPP
◦ 3% of NPP – by one species
◦ Direct + indirect use (40%)
 2/5ths of terrestrial food production
 Fires, conversion (forest  pasture), non-used NPP
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Human population projection
Seas
◦ Whales & fishes
◦ Extinction crisis not as bad
◦ Open seas safer
Ecosystem Services
Gas cycle disruption
 Deforestation
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◦ Freshwater supplies, increases danger of
floods
Insects – pollination of crops
 Biological pest control
 Subterranean organisms – fertility of soil
 Affected without being endangered
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Number of Populations
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Ensure persistence vs. short term changes
◦ Spread the risk
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Genetic diversity
◦ Evolutionary potential in the long term
◦ Lost even without extinction
Consequences
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Food
◦ Climate change, soil erosion, water supplies,
decline of pollinators, pest problems
Benefits from genetic diversity
 Diseases
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◦ e.g. air pollution
Solutions
Human Perception
 Natural reserves not adequate
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◦ Scarcity, climate change
Control of human population growth
 Technology
 Attitudes – public awareness
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Planetary Killer
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Gradual & subtle decline
Red List by IUCN
◦ Extinct
◦ Extinct in the wild
◦ Critically endangered
 Sumatran rhino
◦ Endangered
 Indian rhino
◦ Vulnerable
◦ Near threatened
◦ Least Concern
Red List
Some Causes
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Poaching
◦ Black Rhinos
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Overharvesting
◦ Fish
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Introduction problem
◦ Rats, ants, mosquitoes, weeds
Conversion of natural environments
 Global warming
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Trees as critical cases
976/100,000
 Living dead
 One or few individual / species
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◦ Chinese hornbeam
◦ Hibiscus
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Concentrated endangerment
◦ Juan Fernandez islands
 20 species < 45 indivs
Historical Extinctions by Humans
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Extinction without discovery
◦ Po’ouli
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Islands
 From
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the top of the foodchain down
Big birds, seals, penguins, songbirds, fish, shellfish
Australia & New Zealand
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Australia
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16/263 mammals extinct by European settlers
34 in the Red List
Aboriginals – 60,000 years ago
Large Mammals first
Ground birds/tortoises
New Zealand
◦ Polynesians
◦ No mammals
 Rabbits, deer, rhinos
◦ Moas, New Zealand Eagle
Madagascar
88 millions years of isolation
 Mega animals
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◦ Giant lemur
◦ Elephant birds
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1100 AD, first human settlements
Mauritus
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Dodo
◦ Extinct in 80 years
Mediterranean Area
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Ancestral humans
◦ Tortoises + marine shellfish
Agriculture effects in the Fertile Crescent
 Woolly mammoth, woolly rhino, Irish elk
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Africa & Asia
◦ Cradle of human species
◦ Humans as native species
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Filter principle of conservation biology
Extinction rates
1000 – 10000x
 1/million year
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◦ 1/500,000 years for mammals
◦ 1/6 million years for echinoderms
Current Extinction Rates
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Count the number of extinctions observed
◦ Birds/flowering plants
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Assume the endangered species go extinct
◦ ¼ mammals, 1/8 birds
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Projections/models
◦ Habitat- species relationships
◦ Descent patterns through the red list
◦ Survival probabilities of species
 PVA
Some more solutions
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Captive breeding
◦ California condor
◦ Mauritus kestrel
Natural reserves
 Legislation
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◦ CITES