Extinction and threats to biodiversity

Two major causes Natural Causes (Non-Human) Human Causes

Volcanic Eruptions Drought Meteors Glaciers and ice age Competition and Predation

H-Habitat destruction and fragmentation I- Introduced species P-Pollution P-Practices of agriculture O-Over hunting Dodo Bird – Extinct

Degradation: reducing the quality of available habitat Ex. Logging, agriculture, sewage Fragmentation: splitting a single large, contiguous system into many disconnected areas Ex. Putting a road through a wilderness area, or building a dam across a river Loss: Disappearing of an entire habitat Ex. Paving natural area for building sites, converting prairies to farmland or residential subdivisions

Organisms that are living in an environment outside of its normal range or natural environment Many are transported by accident Biocontrol: Species transported intentionally to control other “problem” species populations Characteristics: Fast growth/reproduction Live in wide range of environments Usually harmful to environment Outcompete native organisms for local food sources Leads to extinction of native organisms

Asian Carp

Originally imported to clear algae from catfish ponds in the southern USA, Flooding allowed some carp to escape into the Mississippi River and its tributaries where they quickly became MANY carp Pose a strong threat to the Great Lakes Asian Carp Research

“the vine that ate the South” and “The Green Menace”. Grow up to 1 foot in a day! Introduced from Japan as quick ground cover to prevent soil erosion

“The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting.” -Thomas Austin in 1859 (Released 24 rabbits) 1950 ~ 600 million rabbits 1951 ~ 100 million Government Drugged Watering Hole

Today starlings are blamed for agricultural losses of up to $800 million annually in the United States, as well as being implicated in a number of deadly plane crashes. ~ 60 were released in New York’s Central Park in 1890.

Good Example of biocontrol! In 1937 cane toads were released in Australia's sugar cane plantations to control insect populations By 1938 ~60,000 cane toads left sugar cane fields for more natural habitat (ate all majority of insect populations and outcompeted native amphibians for food) Can grow up to 15 inches and eat anything!

Toxins added to the environment lead to a loss or degradation of habitat.

Farming causes habitat loss and reduces biodiversity because of… Monoculture: Farming of only one crop on a large scale Pesticides: Often lethal to many non-pest species Herbicides: Lethal to species other than the weeds

Collecting, and harvesting wild populations: unregulated, it can diminish local populations or even drive some to extinction Tasmanian tiger dodo North American sea mink Prairie buffalo Blue whale

Tragedy is that the resource is used by many but none take responsibility for its care Overfishing is an issue in which the current rate of catch is unsustainable

Fossil Records reveal average “lifetimes” of species. Background rate: Naturally occurring rate of extinction (if humans were not on the planet) Humans have lead to a 1,000 – 10,000x increase in the background extinction rate Low Estimate extinction: 200-2,000 species / year High Estimate extinction: 10, ,000 species/year

The Earth has experienced 5 mass extinctions

Extinction # 1 ~445 MYA Ordovician Stage – Dramatic loss of sea level due to forming Antarctica -57% Extinct Extinction # 2 ~ 370 MYA Devonian Stage – Changes in sea level and global cooling stage -50% Extinct Extinction #3 ~250 MYA Permian Stage- Massive change in ocean currents- 83% Extinction Extinction #4 ~200 MYA Triassic Stage – Climate warming from volcanic eruptions -48% Extinct Extinction #5 ~65 MYA Cretaceous – Asteroid impacting the earth – 50% Extinct

Mammals: ~ 1 million years With approximately 5,000 mammals the background rate is 1 every 200 years In past 400 years 89 extinctions have been recorded. 45x background rate. Over 50 extinctions have occurred in the past century 100x background rate

Organisms that are… Limited habitat Extremely specialized niche Low reproductive potential Require a large territory Migratory Valuable economically (hunted) Vulnerable to pollution Incompatible with civilization may be more likely to go extinct

Contain 50% of Earth’s known species Most species have specialized niches Humans disrupt environment for logging Changing one part of ecosystem alters the entire web of relationships Breakdown of rainforest likely lead to extinction of 10% worlds species in 25 years Regeneration rate is slow due to poor soil quality (rapid year round nutrient cycling depletes soil)

IUCN (International Union for Conservation of Nature) Red list used to determine extinction risk Specific Aims: Provide system that can be applied consistently Improve evaluation of different factors which affect the risk of extinction

Population size: How many of this species exist? Reduction in population size: How fast is population decreasing? Numbers of mature individuals: These are past their reproductive years and may lead to further decline Geographic range and fragmentation: Wide range makes the species less likely to be threatened Fragmented habitat reduces interbreeding populations Quality of habitat: Degraded habitat supports fewer individuals

Extinct (Ex) – All members of species are deceased Extinct in Wild (EW)- Only found in captivity Critically Endangered (CR) – Extremely high risk of extinction in wild Endangered (E)- At a very high risk of extinction Vulnerable (V) –Under threat from serious factors leading to potential severe declines in populations Near Threatened (NT) – Small world populations that are at risk. Almost considered vulnerable Least Concern (LC)– Species do not qualify because populations are abundant and widespread.