Zusammenfassung der Ressource
B2.6 Old and New Species
- The Origins of Life on Earth
- There is no evidence for the
origin of life on Earth yet we
believe it was 3-4 Billion years
ago
- What can we learn from fossils?
- They are the remains
of organisms
preserved in rock
- How they form:
- From hard parts
the animal that
do not decay
- None of the animal
decays properly
because of little or no
oxygen or bacteria
and temperature
- Hard parts of the
animal are replaced
with minerals
- Some are footprints or
traces of animals
- Lack of evidence
- Many of the earaliest life forms were soft
bodied organisms so created no fossils
- Most of the time, fossil
conditions were not right
so many organisms
didn't get fossilised
- Many fossils have been
destroyed by geological
activity
- How something gets fossils
- 1) The reptile dies
and falls to the
ground
- 2) The flesh rots
leaving the
skeleton buried in
clay, sand or soil
- 3) over millions of
years, the skeleton
becomes mineralised
and becomes rock
- 4) the fossil emerges
- Exploring Fossil Evidence
- Using the fossil record
- We have enough
fossils to understand
how specific species
went through
evolution
- Some species such as sharks adapted very
early and haven't changed since as there is
no reason for them to
- Extinction
- Roughly 4 Billion
species have existed
and many are extinct
- As conditions change species must evolve to suit the
conditions. If they can not, then die out
- Some species are
completely dead and
others have living relative
- Causes can include new
predators, new diseases,
or more successful
competitivors.
- The change of
climate may both
cause species to
evolve or die
- Organisms that cause extinction.
- New predators wipe out
prey quickly as the pray can
not escape. This is
sometimes to human
intervention.
- New diseases caused by microorganisms can
quickly spread and cause species to die. This is
common on islands. The Australian Tasmanian
Devil is dying of cancer
- Some organisms can cause others to be
extinct by adapting and taking their food
such as rabbits in Australia
- More about Extinction
- The biggest influences
on species is a change
in their environment
- Environmental Changes
- changes to the climate
have been the main
cause of extinction
- There have been 5 different occasions of
extreme extinction from climate change
- Extinction on a Large Scale
- Mass extinction
usually happens over
a short period of
several million years
- single catastrophic event
like an asteroid, supernova
or volcanic eruption
- The Dinosaurs
- 65 million years ago,
asteroid collided with
Earth in Mexico
- The asteroid caused
tsunamis, fires,
earthquakes, landslides
and fired dust
everywhere causing a
global dark winter and
plant life to die
- 50-70% of all
species became
extinct including
dinosaurs
- Another theory
is that global
warming caused
sea ice to melt
and drop water
temperature by
9°C
- Isolation and the evolution of new species
- Isolation and Evolution
- If two of the same species
become isolated from each
other in different conditions,
different genetic variety will
be dominant. The two
populations lose the ability to
breed and become a new
species
- Geographical
isolation is the
easiest way to cause
isolation
- Mountain range, river, island
- Australia
- Organisms in isolation
- When a species
evolves in isolation
and is only found in
one area it is endemic
- In Borneo this is very common
- Speciation
- alleles for characteristics
enable organisms to
survive and breed in new
conditions .
- When species can no
longer breed with
originals, this is
speciation