Extinctions and Radiations Part 3-Lesson 1. Classification Life forms are constantly undergoing changes and evolving. Scientists have created a classification.
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Slide 1
Extinctions and Radiations Part 3-Lesson 1
Slide 2
Classification Life forms are constantly undergoing changes and
evolving. Scientists have created a classification system to keep
track of this and show how organisms are related.
Slide 3
Classification
Slide 4
This classification system sorts and groups similar organisms
to show where an organism fits with the entire scheme of living
things. This is called taxonomy (the practice and science of
classification).
Slide 5
Classification Kingdom is the broadest of all groups in the
classification system and species is the narrowest. The kingdom
group contains organisms that are not very closely related while
the species group contains organisms which are very closely
related.
Slide 6
Classification The groups in between kingdom and species show a
gradual decrease in difference between organisms within each level.
As you go from Kingdom to species, the similarity of organisms
increase.
Slide 7
Gradual or explosive? The rate of evolution has not been
constant. There were times of both gradual and explosive periods of
evolution. The rate of evolution depends on the rate of mutation
and environmental change.
Slide 8
Gradual or explosive? As discussed before, mutations are random
changes in an organisms genetics. During periods of frequent or
large environmental change, evolution occurs explosively or rapidly
as organisms try to keep up with the changes. When there is little
environmental change, evolution is not necessary for organisms to
survive.
Slide 9
Gradual or explosive? Extinctions can also be gradual or
explosive. They too have occurred regularly throughout geologic
time. Extinctions and evolutionary radiation are often linked.
Slide 10
Gradual or explosive? If the rate of extinction is low, it is
likely the rate of evolutionary radiation that follows will be low.
If the rate of extinction is high the rate of evolutionary
radiation that follows will be high.
Slide 11
Gradual or explosive? After a mass extinction, environments
become less populated therefore allowing surviving organisms to
colonise and evolve in the empty environment. The rate of evolution
can be recorded and graphed by looking at the number of new
organisms appearing over time.
Slide 12
Homework Read pages 93-95 HCS Spotlight Text Update electronic
vocabulary Complete activity 2.11 page 56 Complete DOT Point
5.2
Slide 13
Mass Extinctions Part 3-Lesson 2
Slide 14
Mass Extinctions Two of the most studies mass extinctions
occurred at the end of both the Permian and Cretaceous. Activity:
-Add these to your timeline
Slide 15
Mass extinctions The Permian extinction was the most
devastating in geologic history as almost 95% of all marine species
and a large number of terrestrial species died out.
Slide 16
Mass extinctions There are many theories to try and explain the
causes for mass extinctions including glaciations, volcanic
eruptions and meteorite impacts. Its thought that the cause of the
Permian extinction was due to large scale glaciations. Global
temperatures would have lowered and sea levels would have also
lowered as water would have been locked up in ice.
Slide 17
Mass extinctions The mass extinction at the end of the
Cretaceous resulted in the extinction of the dinosaurs and
approximately 40% of all known species of the time. The most
popular theory which explains this extinction is a meteorite
impact.
Slide 18
Mass extinctions Such a meteorite impact would force tonnes of
materials into the atmosphere blocking out large amounts of solar
radiation. This would have caused global temperatures to
decline.
Small extinctions Extinctions are not always caused by natural
environmental factors. Humans and other large predators have also
caused extinctions.
Slide 22
Small extinctions For example, the extinction of the Australian
megafauna is believed to be largely because of human intervention.
Megafauna were slow movers which made them easy prey for humans. It
is suggested that the arrival of humans to Australia coincided with
the extinction of the megafauna.
Slide 23
Small extinctions This type of extinction directly targets a
group of animals and is therefore termed as small. A mass
extinction impacts on a wide range of organisms in a geologically
small period of time.
Slide 24
Small extinctions The extinction of Australias megafauna
targeted mostly large marsupials but a significant amount of
smaller marsupials were able to survive. Climate change may have
also played a part in the extinction of megafauna and survival of
smaller marsupials in Australia.
Slide 25
Activity Complete activity 2.14 page 97 HSC Spotlight Text
together.
Slide 26
Homework Update electronic vocabulary Complete DOT Point
5.6-5.8
Slide 27
Current rate of extinction Part 3-Lesson 4
Slide 28
Current rate of extinction Why is Australia unique? We are an
island continent and have been so for a very long time. This has
allowed large amounts of Australia flora and fauna to become
endemic and diverse.
Slide 29
Current rate of extinction However this has also made Australia
sensitive to extinctions. At present the entire world is
experiencing a very high extinction rate. Current estimates suggest
it is between 1000 and 10000 times greater than is would naturally
be. Australia has the highest rate in the world.
Slide 30
Current rate of extinction This is because of the destruction
of natural habitats and unsustainable management of the country.
This has ALL been caused by humans.
Slide 31
Current rate of extinction In the last 200 years, since
European settlement, 18 species of mammals and approximately 100
species of plants have become extinct. 40 species of mammals and
hundreds of species of plants are today endangered.
Slide 32
Current rate of extinction We need to address and take action
now to stop this rate and bring it under control. What do you think
the future of the biodiversity of Australia is? What can you do to
reduce the extinction rate?