The Loss of Biodiversity ESC 556 Week 9

Causes and Consequences Prominent species & causes ◦ Endangered Species ◦ Overexploitation by humans

Causes and Consequences Obscure species & causes ◦ Habitat destruction ◦ Plants & insects ◦ Loss of free services ◦ Loss of genetic diversity

Habitat Destruction Thousands threatened vs. a few overexploited ◦ Plowing, logging, overgrazing, flooding, draining…. Dependence on habitats ◦ Birds  mature tropical forests ◦ Bats  caves ◦ Trout  Can’t breed in acidic or too warm water

Human impact NPP ◦ 3% of NPP – by one species ◦ Direct + indirect use (40%)  2/5ths of terrestrial food production  Fires, conversion (forest  pasture), non-used NPP Human population projection Seas ◦ Whales & fishes ◦ Extinction crisis not as bad ◦ Open seas safer

Ecosystem Services Gas cycle disruption Deforestation ◦ Freshwater supplies, increases danger of floods Insects – pollination of crops Biological pest control Subterranean organisms – fertility of soil Affected without being endangered

Number of Populations Ensure persistence vs. short term changes ◦ Spread the risk Genetic diversity ◦ Evolutionary potential in the long term ◦ Lost even without extinction

Consequences Food ◦ Climate change, soil erosion, water supplies, decline of pollinators, pest problems Benefits from genetic diversity Diseases ◦ e.g. air pollution

Solutions Human Perception Natural reserves not adequate ◦ Scarcity, climate change Control of human population growth Technology Attitudes – public awareness

Planetary Killer 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 Poaching ◦ Black Rhinos Overharvesting ◦ Fish Introduction problem ◦ Rats, ants, mosquitoes, weeds Conversion of natural environments Global warming

Trees as critical cases 976/100,000 Living dead One or few individual / species ◦ Chinese hornbeam ◦ Hibiscus Concentrated endangerment ◦ Juan Fernandez islands  20 species < 45 indivs

Historical Extinctions by Humans Extinction without discovery ◦ Po’ouli Islands From the top of the foodchain down Big birds, seals, penguins, songbirds, fish, shellfish

Australia & New Zealand Australia ◦ 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 ◦ Giant lemur ◦ Elephant birds 1100 AD, first human settlements

Mauritus Dodo ◦ Extinct in 80 years

Mediterranean Area Ancestral humans ◦ Tortoises + marine shellfish Agriculture effects in the Fertile Crescent Woolly mammoth, woolly rhino, Irish elk

Africa & Asia ◦ Cradle of human species ◦ Humans as native species Filter principle of conservation biology

Extinction rates 1000 – 10000x 1/million year ◦ 1/500,000 years for mammals ◦ 1/6 million years for echinoderms

Current Extinction Rates Count the number of extinctions observed ◦ Birds/flowering plants Assume the endangered species go extinct ◦ ¼ mammals, 1/8 birds Projections/models ◦ Habitat- species relationships ◦ Descent patterns through the red list ◦ Survival probabilities of species  PVA

Some more solutions Captive breeding ◦ California condor ◦ Mauritus kestrel Natural reserves Legislation ◦ CITES