Transcript Natural Selection

Variation and Natural Selection Notes
Charles Darwin
Mutations
Variations
Natural Selection
Adaptations
Selective Breeding
Evolution
How Does All of This Fit Together?
Variation and Natural Selection Notes
Charles Darwin
Scientist during the 1800’s that traveled
around the world making observations
of nature.
Darwin discovered from his travels that
organisms have structural
characteristics that enable them to live
in their environment – Adaptations!
Background Information
Variation and Natural Selection Notes
Darwin’s Finches
As Darwin was observing birds on the
Galapagos Islands, he discovered that
there were many variations of one kind
of bird – the Finch.
Variations are differences in form of an organism
within the same species or group.
Background Information
Variation and Natural Selection Notes
Darwin’s Finches (Continued)
These birds that would later become
nicknamed as “Darwin’s Finches”
proved that organisms adapt to live in
their environment.
Each of Darwin’s Finches have a beak that is
specifically designed to eat the type of food that is
available in its environment.
Background Information
Variation and Natural Selection Notes
Darwin’s Finches (Continued)
Each one of these Finches was found on a different
Galapagos Island. This illustration shows how various
Finches adapted to eat the type of food available to them.
Background Information
Variation and Natural Selection Notes
How Do
Adaptations
Come About?
How Do Adaptation Come About?
Variation and Natural Selection Notes
Mutations
A mutation is where there is a random
change in genetic information in an
organism.
Mutations can be good and they can be bad.
If a mutation is good, it will help and organism to live.
If a mutation is bad, it will often cause the organisms
to die.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Mutations
Good or Beneficial Mutations
Below is a picture of a Black Jaguar (Left). This color
mutation is good because it helps the Jaguar to hunt
at night, blending into the night time landscape.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Mutations
Bad or Harmful Mutations
Below is a picture of a two headed calf . This type of
mutation is bad because the animal is not able to
survive.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Variations
Good mutations lead to variations.
When mutations are good, the organism survives to
pass the mutation on to it’s offspring. As more and
good mutations are passed on, more variations of a
species become present as in these parakeets below.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Natural Selection
Mutations which lead to variations also
lead to natural selection.
Natural selection occurs when good mutations are
passed on to offspring.
Natural selection is often referred to as “Survival of
the Fittest”. Organisms that have “stronger”
mutations or characteristics survive and the
organisms that have “weaker” characteristics die.
The organisms with the stronger characteristic are able to pass
their stronger characteristics on to their offspring. The organisms
with the weaker characteristics die and are unable to pass their
weaker characteristics on.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Natural Selection Example
How Do Adaptations Come About?
Variation and Natural Selection Notes
Natural Selection Example (Cont.)
How Do Adaptations Come About?
Variation and Natural Selection Notes
Natural Selection Example (Cont.)
How Do Adaptations Come About?
Variation and Natural Selection Notes
Adaptations
Over very long periods of time, the good
mutations that get pass on and on over
several generations become known as
adaptations.
Adaptations take hundreds, thousands, or even
millions of years to come about.
If an organism is not able to adapt, it will die. If an
entire species is unable to adapt, the whole species
will die and become extinct.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Selective Breeding
Selective breeding is when animals are bred
on purpose to bring about desired traits.
Below is a picture of a horse (left) and donkey
(middle) and a mule (right). When a horse is bred
with a donkey a mule is produced. A mule has the
strength of a horse and the sure footedness of a
donkey.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Selective Breeding
Selective breeding is when animals are bred
on purpose to bring about desired traits.
Below is a picture of a horse (left) and donkey
(middle) and a mule (right). When a horse is bred
with a donkey a mule is produced. A mule has the
strength of a horse and the sure footedness of a
donkey.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Selective Breeding
Selective breeding can also bring about
bad or undesirable traits
Some breeds of dogs are selectively bred for their
aggressiveness, however, this sometimes produces
dogs are too aggressive an cannot be controlled.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Evolution
Evolution is the end product of
adaptations. As mutations, variations,
natural selection, and adaptations occur,
organisms continue to change to
become ever better suited for their
environment.
How Do Adaptations Come About?
Variation and Natural Selection Notes
Evolution
The evolution of the horse.
The modern day horse may have looked something
like a dog, but over millions of years of natural
selection and adaptations, this animal changed into
what we now know as a horse.
How Do Adaptations Come About?