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Starter
• Write down four factors that you think will
make a species more prone to extinction.
• Think about endangered species that you know and
species that you know have gone extinct.
Learning outcomes
• You should be able to:
– Describe and explain the factors that may make
species more or less prone to extinction.
– Outline the factors used to determine a species’
Red List conservation status.
– Look at the command terms… what do they
mean?
– So what would you need to be able to do to
achieve this outcome?
Small population size / declining numbers
“Lonesome George” – Pinta Island giant
tortoise
http://www.telegraph.co.uk/
Low reproductive
potential
Humpback whale
Narrow geographical
range
A large body
Tiger
Golden lion tamarin
http://wwf.panda.org/
Different characteristics make
species more / less vulnerable
to extinction…
http://www.allaboutwildlife.com/golden-liontamarin-saved-from-extinction
Hunting
Specialised feeders,
niche requirements
Panda
The now extinct
Thylacine
http://worldwildlife.org/species/giant-panda
http://animals.nationalgeographic.com
http://blogs.scientificamerican.com
Read the article
• The article gives lots of different
characteristics that can cause extinction.
• Read what it has to say and complete the
table as you go.
IUCN Red List
International Union for the Conservation of Nature
The Red List is an inventory of all threatened species.
The main purpose of the list is to highlight plants and animals facing a higher risk of
global extinction than others.
Various factors are used to determine the conservation status of species:
Reduction in
population size
Geographic range and
degree of fragmentation
Quality of habitat
Members of mature
individuals
Population size
Area of occupancy
Probability of extinction
Evaluation criteria
• For the species that have been evaluated and
where there is enough data, the following criteria
are used:
–
–
–
–
–
–
–
Extinct
Extinct in the Wild
Critically endangered
Endangered
Vulnerable
Near Threatened
Least Concern
Threatened
Some of the species on the list…
The Black Rhinoceros (Diceros bicornis) Critically Endangered. Its population
has declined by an estimated 97.6% since 1960, with numbers bottoming out
at 2,410 in 1995, mainly as a result of poaching. Since then, numbers have
doubled to 4,880 by the end of 2010. Current numbers are however still 90%
lower than three generations ago. Photo © Steve Garvie,
http://creativecommons.org/licenses/by-nc-sa/2.0/
Described in 2010, the Caquetá Tití Monkey(Callicebus caquetensis) has been
assessed for the first time in 2012 as Critically Endangered. It is endemic to
eastern Colombia, and occurs in an area subject to intense human colonization
that has caused widespread habitat destruction and fragmentation. Photo
© Javier Garcia
Previously thought to be extinct, the Hula Painted Frog (Discoglossus nigriventer) of
Israel was rediscovered in 2011. The Huleh marshes were drained in the 1950s in an
attempt to both eradicate malaria and to make the land suitable for agricultural
use. The remaining wetland (5% of the original area) was set aside as the Hula
Nature Reserve in 1964. The reserve is well-managed but functions as a refuge for
many water birds; predation by birds is thought to be a real threat to the small
population of this frog. In addition, most of the surrounding area is cultivated. This
frog is now listed as Critically Endangered. Photo ©Oz Rittner, TAU - Zoological
Museum, Steinhardt National Collections of Natural History, Israel
Checking outcomes
• List 5 characteristics that make a species more
vulnerable to extinction.
• Explain why these characteristics increase
vulnerability to extinction.
• List the characteristics that are used to
determine the conservation status of a
species.
Activity – in pairs
• Choose 3 species of your choice:
– One that has become extinct
– One that is critically endangered
– One whose conservation status has been improved by
intervention
• Research the case histories of your species:
– You should find out:
• The socio-political, ecological and economical pressures that
caused / are causing the chosen species’ extinction.
• The ecological roles of each species and the consequences of their
disappearance.
• Be ready to present the information in the next class.
• http://www.philropost.com/2012/04/extinctare-humans-next.html
A natural area of biological significance that is threatened…
Stretches 2300 kilometres and is home to
1500 species of fish, 359 types of hard coral,
a third of the workld’s soft coral, 6 of the
world’s 7 species of threatened turtle and
more than 30 species of marine mammal.
http://www.greatbarrierreef.org/about.php
Human threats
• Tourism – people take bits of coral as souvenirs
• Over-fishing – disrupts the balance of species
• Seafloor trawling – destruction of seafloor.
• Soil run-off – inorganic nitrogen pollution has
increased by 3000%
• Sedimentation – mud pollution
• Global warming – increase insea temperatures
Natural threats
• Crown-of-thorns starfish – feeds
on polyps
• Storms and cyclones
• El Niño
Homework
Research and write about an area of biological
significance that is under threat from human
activity:
• Identify why it is an area of biological
significance
• Identify the human threats and natural threats
affecting the area.
• Identify what is happening and use the Great
Barrier Reef example to help you.