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EVOLUTION
EVOLUTION is the development of living things over geological time
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Natural Selection: how living things evolve
All organisms compete with each other for food, shelter, mates and an escape from
predators; however individual organisms will show a wide range of VARIATION because
of differences in their genes
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The
mutant will have an advantage which will increase their chance of survival
above others of their organism
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 The weak die out and the survivors reproduce
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This is how nature is evolving to become more and more advanced because the weaker
ones are dying out whereas those who have mutated are passing their advanced genes
down to their offspring (INHERITANCE)
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Finches
In the Galapagos Islands, Darwin noticed the same species of finch on each island
looked the same apart from their beaks- which were different depending on the local
food source
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They were too distant
from the mainland to have migrated recently so Darwin concluded that the finches
that had arrived there a long time ago had changed over time to adapt to their
nearest food source (environment)
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This is older than the Bible suggests and the
theory itself implies that God did not create and develop all organisms, evolution did
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Some can grant an organism’s characteristic with a disadvantage, which can
decrease their chance of survival
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Negative
mutations therefore don’t have a big impact on evolution because its owners are usually
dead before they can pass the gene down to offspring
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From
the theory, he concluded with individuals who are poorly adapted to their
environment are less likely to survive and reproduce
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Given enough time, a species will gradually evolve
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This was because they contradicted religion, which
played a very big role in his time
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The
trigger to finally publish ideas was the news that other rising naturalists around
Europe were discovering their own ideas about evolution and Darwin needed the
credit for his findings before anyone else took it from him
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19 th century rising French botanist Jean-Baptiste
Lamark had his own theory of evolution: A characteristic of an organism strained
becomes bigger and stronger, whereas if it is not strained it dies out
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This was called THE
INHERITANCE OF ACQUIRED CHARACTERISTICS
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The giraffe strains its
neck to reach the leaves
on the high tree

2)
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This neck characteristic
is passed down through
the genes

2)
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This characteristic is
passed down so all his
children are born dench too

OR

1)
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That is not true
because simple organisms are still around today
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EVIDENCE FOR EVOLUTION

Fossils
FOSSILS are the remains or imprints of dead organisms in rocks and land
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For instance
enough fossils of horses have been found to cover their main stages of evolution
throughout 60 million years of existence:
What are the disadvantages about using fossils as
evidence for evolution?
Not all types of organism produce a fossil when they die
so there are some gaps when trying to prove the main
stages of evolution for particular species
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Similarities between organisms
In his studies, Darwin realised that the embryos of
completely different animals looked the same until a few
weeks of conception
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SALAMANDA HUMAN

RABBIT

CHICKEN

FISH

Sudden Adaptions
These also support Darwin’s theory because they explain that living things evolve to
adapt to their environment over time
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Therefore those moths with a black mutation survived better
and were more likely to reproduce
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EXTINCTION
EXTINCTION is when a species of living organism die out and no longer exist
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The FOSSIL RECORD shows that a lot of species have
become extinct since life on Earth began
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Human activities can also have
a big impact on extinction:
 We are good predators (we always win the food and resources etc)
 Hunting/deforestation affects population
 Colonisation brings over new organisms which will either become predators or
hog all the inhabitant’s resources
 Migration can bring over disease
 Humans contribute to global warming which can change climate quickly
EXAMPLE: THE DODO
The dodo is the most common example of an extinct species
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In under a
century, it became extinct
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g
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CLASSIFICATION OF SPECIES
THE NATURAL CLASSIFICATION SYSTEM is the system scientists use to group
organisms on their similarities to make more sense of how closely they are related
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The main kingdoms are:
 The Plant Kingdom
 The Animal Kingdom
 The Fungi Kingdom
 The Prokaryote (Bacterium) Kingdom
 The Protoctist Kingdom (Amoeba, Chlorella and Plasmodium)
SPECIES are the smallest groups in the system
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When two or more organisms are linked at some point back in time, it means they
have an EVOLUTIONARY RELATIONSHIP
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EVOLUTIONARY TREES are
diagrams that show the links between different organisms back in time
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Usually, the more different the types of
organisms are today, the longer ago the species split
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EXAMPLE OF AN
EVOLUTIONARY TREE:
Describes the link between
different kingdoms and species

VARIATION: ONE SPECIES TO MANY
So why are there so many species of the same fish in the Lake Victoria?
Lake Victoria in Africa was formed about 1500 years ago
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This is called “Darwin’s Dreampond” because the 500 species back up his theory of
evolution and natural selection perfectly
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This could be depending on their nearest food source etc (like
Darwin’s finches)
Different species of cichlid can mate to create a HYBRID (half of each)- which in itself
could be a whole new species
Some forms of cichlid are migrant, from other lakes in Africa like Kivu

Variation in humans
A unique mix of genes from the mother and father are
passed down: some types of variation don’t really
matter like colours of eyes but some do like
metabolism and resistance/immunity to viruses
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They would eventually become a
very different species of homo sapien because natural
This diagram shows how one species can
become many and how some species selection will favour different characteristics to those
disappear
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environment best
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Evidence shows that they should both be the
same monkey, but one type has evolved to adapt to one part of Africa and one has evolved
to adapt to the other, so they are now very different

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