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Extinction

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Extinction

Extinction

The Definition and Causes

What is Extinction?

Extinction occurs when the last existing member of a given species dies

In other words…there aren’t any more left!

It is a scientific certainty when there are not any surviving individuals left to reproduce

Functional Extinction

Only a handful of individuals are left

Odds of reproduction are slim

Causes of Extinction

Genetics and Demographics

Small populations = increased risk

Mutations

• Causes a flux in natural selection

• Beneficial genetic traits are overruled

Loss of Genetic Diversity

• Shallow gene pools promote massive inbreeding

Causes Con’t.

Habitat Degradation

One of the most influential

Has many causes

Some due to humans

Some due to other factors

Habitat Degradation

Toxicity

Kills off species directly through food/water

Indirectly via sterilization

Can occur in short spans (a single generation)

Can occur over several generations

• Increasing toxicity

• Increasing competition for habitat resources

Habitat Degradation

Destruction of Habitat

“Save the Rainforests!”

Elimination of living space

Change in habitat

• Rainforest to pasture lands

Leads to diminishing resources

• Increases competition

Can be caused by natural processes

• Volcanoes, floods, drought, etc…

Causes Con’t.

Predation

Competition

Disease

Coextinction

Mass Extinction

Planned Extinction

Predation

Introduction of predators

Invasive alien species

Transported by humans

• Cattle, rats, zebra muscles, etc…

• Sometimes on purpose, sometimes not

Can eat other species

Eat food sources

Introduce diseases

Coextinction

The loss of one species leads to the loss

of another

Chain of extinction

Can be caused by small impacts in the

beginning

A predator looses its food source

Affected by interconnectedness in nature

Mass Extinction

Aka: an extinction event

A sharp decrease in the number of

species on Earth in a short period of time

Coincides with a sharp drop in speciation

The process by which new biological species

arise

There have been at least 5

Last one was 65M years ago

Mass Extinction Diagram

Mass Extinction

Nearly 2/3rds (or more) of all animal

species that ever existed on the planet are

now gone. • With contemporary extinction being attributed to

HUMAN activity.

Numerous factors go into the extinction of

a specific species.• Though all point the finger to climate change.

Mass Extinction

Began about three-million years ago (Continental Glaciations).

Hypotheses for initial extinction:• Sea level depletion vs. Temperature decrease

Though these hypotheses aren’t mutually exclusive, they may have conspired together.

Mass Extinctions

1. Cretaceous-Tertiary Extinction (65).

2. End Triassic Extinction (200).

3. Permian Triassic Extinction (250).

4. Late Devonian Extinction (364).

5. Ordovician-Silurian Extinction (440).

(#= millions of years ago)

Planned Extinction

Human controlled

Thought of to help humans

Deadly viruses

Smallpox

• Extinct in the wild

Polio

• Near extinct (only in small parts of the world)

Natural Causes of

Extinction

Climatic Heating and Cooling

Changes in Sea Level or Currents

www.johnstonsarchive.net/spaceart/cylmaps.html

Asteroids

Causes complete

devastation

Flattening and crater at

or around impact site-

hundreds of miles wide

Reverberations felt around

the world

Cosmic Radiation

www.iit.edu/~ipro313s/home.html

Acid Rain

Kills acid intolerant

species

Disease/Epidemics

Can wipe out entire

species

Frog with fungus

disease

Killing frogs and other

amphibians

Spread of Invasive Species

Natural factors usually occur at a slower

rate and therefore cause a low extinction

rate. Human activities occur at a faster

rate and cause higher extinction rates.

Human activities are mostly responsible

for the present extinction rates.

http://www.gov.mb.ca/conservation/sustain/extinct.pdf

Human Causes of

Extinction

Top Human Causes of

Extinction:

Increased human population

Destruction/Fragmentation of

habitat

Pollution

Climate change/Global warming

Extinctions caused by humans are generally

considered to be a recent phenomena. HOWEVER:

•In Australia—earliest humans: 64,000 years ago

extinction—30,000-60,000 years

ago

•In the Americas—80% of large animals became

extinct around the same time as first human presence

there

Based on these, and other

studies done by The

international Union for

Conservation of Nature

and Natural Resources

(IUCN), human induced

extinctions are not

necessarily a new

phenomena. However,

extinction by humans today

is becoming much more

rapid.

The rapid loss of species today is estimated by some

experts to be between 100 and 1,000 times higher than

the natural extinction rate, while others estimate rates as

high as 1,000-11,000 times higher.

Habitat Degradation

Habitat loss and degradation affect 86%

of all threatened birds, 86% of mammals and

88% of threatened amphibians

Climate change/Global Warming

John W. Williams from UW-Madison suggests that changes

in regions such as the Peruvian Andes, portions of the

Himalayas and southern Australia could have a profound

impact on indigenous plants and animals

Williams and his research partners used computer models

to estimate how various parts of the world would be

affected by regional changes consistent with the IPCC's

climate models.

Their findings indicated that “By the end of the 21st century,

large portions of the Earth’s surface may experience

climates not found at present and some 2th century

climates may disappear.”

Their studies also suggest isolated climates such as the

Peruvian Andes could change drastically enough to lead

to species extinctions.

The climate change might also create new climates,

providing new opportunities for other species to thrive,

Williams said.

Regions where

novel climates are

expected to form in

tropical and

subtropical regions

include the western

Sahara,

southeastern U.S.

and eastern India.

Extinction Hotspots

Where and what are hotspots?

“The concept of biodiversity hotspots was penned by British ecologist Norman Myers in 1988 as a means to address the dilemma of identifying the areas most important for preserving species.” (national geographic)

Hotspots are included in 6 continents excluding Antarctica.

Hotspots are heavily distributed along shore lines and near the equator.

Hotspots are effected by many factors including

Logging

Agriculture

Hunting

Climate change

Government

Hotspots can be added and removed from the classification of “hotspot” by what recovery or lack of prevention is taking place in each area.

What is required to be considered a

hotspot

“The region must support at least 1,500

plant species found nowhere else in the

world, and it must have lost at least 70

percent of its original habitat.”

Interactive maps

http://www.biodiversityhotspots.org/xp/Hot

spots/home/interactive_map.xml

http://www.zeroextinction.org/pointmapper/

azefiles/index.html

What is Biodiversity? Biodiversity is the variation of taxonomic life

forms for a given biome or ecosystem

Boosts Ecosystem productivity

Measure of the health of a biological system

Benefits of Biodiversity

Food and drink

Medicines

Industrial materials

Ecological services

Leisurely, cultural, and

aesthetic values

Causes of Biodiversity Loss

Pollution

Loss of tropical forest

Spread of urban areas

Warfare

Large dam construction

Road building

Tourism

Loss of traditional

lifestyles

Consequences of Biodiversity Loss

Loss of food

Decrease in biomass

Collapse of food web

Loss of keystone species

Reduction of ecosystem efficiency and community productivity

Loss of medicinal supplies

Increased vulnerability of species to disease and predation

CropsMonoculture of crops lets the yield

become susceptible to pests or viruses

75% of crop varieties are extinct

Due to the spread of modern agriculture

Tropical Forest Cutting

Cover 13% of Earth

Home to 50% of all known plant and animal

species

FAO reports 15.4 million hectares are

destroyed annually

The Convention on Biological

Diversity

Mission Statement

“The objectives of this convention are the

conservation of biological diversity, sustainable

use of its components and the fair and equitable

sharing of the benefits arising out of the

utilization of genetic resources.”

Since it was adopted at the Earth Summit in Rio de Janeiro in 1992,

189 countries have signed and implemented it. The United States

signed it in 1993 but has yet to put it into action still today

The Convention on Biological

Diversity

2010 Biodiversity Target

Members adopted a plan to significantly reduce the present

rate of biodiversity loss at the global, regional and

national level by the year 2010.