Transcript Natural Causes of Extinction

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
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Only a handful of individuals are left
Odds of reproduction are slim
Causes of Extinction
 Genetics
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and Demographics
Small populations = increased risk
Mutations
• Causes a flux in natural selection
• Beneficial genetic traits are overruled
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Loss of Genetic Diversity
• Shallow gene pools promote massive inbreeding
Causes Con’t.
 Habitat
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Degradation
One of the most influential
Has many causes
Some due to humans
Some due to other factors
Habitat Degradation
 Toxicity
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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
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of Habitat
“Save the Rainforests!”
Elimination of living space
Change in habitat
• Rainforest to pasture lands
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Leads to diminishing resources
• Increases competition
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Can be caused by natural processes
• Volcanoes, floods, drought, etc…
Causes Con’t.
 Predation
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Competition
Disease
 Coextinction
 Mass
Extinction
 Planned Extinction
Predation
 Introduction
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of predators
Invasive alien species
Transported by humans
• Cattle, rats, zebra muscles, etc…
• Sometimes on purpose, sometimes not
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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
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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.
2.
3.
4.
5.
Cretaceous-Tertiary Extinction (65).
End Triassic Extinction (200).
Permian Triassic Extinction (250).
Late Devonian Extinction (364).
Ordovician-Silurian Extinction (440).
(#= millions of years ago)
Planned Extinction
 Human
controlled
 Thought of to help humans
 Deadly viruses
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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 sitehundreds 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?
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“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)
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Hotspots are included in 6 continents excluding
Antarctica.
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Hotspots are heavily distributed along shore
lines and near the equator.
 Hotspots
are effected by many factors
including
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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?
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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
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Pollution
 Loss of tropical forest
 Spread of urban areas
 Warfare
 Large dam construction
 Road building
 Tourism
 Loss of traditional
lifestyles
Consequences of Biodiversity Loss
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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
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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.”
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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
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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>.