Extinction.ppt

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
 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)

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

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

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.

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

Crops
Monoculture 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.

References
 Ceballos, G., and Ehrlich, P., 2002, Mammal Population Losses and the Extinction
Crisis:
 Science, v. 296, p. 904-908.
 Fahrig, L., 2002, Effect of Habitat Fragmentation on the Extinction Threshold: A
 Synthesis: Ecological Applications, v. 12, p. 346-353.
 Gittleman, J., The Risk of Extinction—What you don’t know will hurt you: Science, v.
291.
 Petcchey, O.L., and Gaston, K.J., Extinction and the loss of functional diversity: They
Royal
 Society, p. 1721-1727.
 Rutledge, D., Lepczyk, C., Xie, J., Liu, J., 2001, Spatiotemporal Dynamics of
Endangered
 Species Hotspots in the United States: Conservation Biology, v. 15, p. 475- 487.
 Kent, Holsinger. "The Causes of Extinction." 27 Aug. 2005. 12 Mar. 2007
<http://darwin.eeb.uconn.edu/eeb310/lecture-notes/extinctions/node3.html>.
 Madeley, J., Warnock, K., 1995, Biodiversity: A Matter of Extinction: The challenge of
protecting the South’s biological heritage <http://www.panos.org.uk/pdf/reports/
biodiversity.pdf>.
 Trombulak, Stpehen C., et. Al. 2004, Principles of Conservation Biology: Recommended
 Guidelines for Conservation Literacy from the Education Committee of the Society for
 Bald Eagle. US Fish and Wildlife Service <http://www.fws.gov/endangered/i/b/msab0h.html>.
 Conservation Biology: Conservation Biology
<http://www.conbio.org/Resources/Education/conservation_literacy_english.pdf>.
 Extinction. Lecture by Bruce Walsh at University of Arizona, 1995.
 <http://nitro.biosci.arizona.edu/courses/EEB105/lectures/extinction/extinction.html>.

References
Trombulak, Stpehen C., et. Al. 2004, Principles of Conservation
Biology: Recommended
Guidelines for Conservation Literacy from the Education
Committee of the Society for
Bald Eagle. US Fish and Wildlife Service
<http://www.fws.gov/endangered/i/b/msab0h.html>.
Conservation Biology: Conservation Biology
<http://www.conbio.org/Resources/Education/conservation_literac
y_english.pdf>.
Extinction. Lecture by Bruce Walsh at University of Arizona, 1995.
<http://nitro.biosci.arizona.edu/courses/EEB105/lectures/extinctio
n/extinction.html>.

Extinction.ppt

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Extinction.ppt