Download Evolution and Natural Selection Lesson

EVOLUTION
In biology, Evolution refers to the process through which species
change over time. The change results from a change in the genetic
material of an organism and is passed from one generation to the
next.
Charles Darwin
12 February 1809 – 19 April 1882
Darwin was an English naturalist who is best known for
his contributions to the theory of evolution. He
established that all species of life have descended over
time from common ancestors and that evolution
resulted from a process that he called natural
selection.
There is grandeur in this view of life,
with its several powers, having been
originally breathed into a few forms or
into one; and that, whilst this planet
has gone cycling on according to the
fixed law of gravity, from so simple a
beginning endless forms most beautiful
and most wonderful have been, and are
being, evolved.”
The Voyage of the Beagle
The Galapagos Islands
Darwin spent 5 years in his mid
20’s aboard the Beagle exploring
and collecting specimens. It was
his time visiting the volcanic island
chain off the coast of Ecuador that he began to notice
that each island had a different environment and that
plants and animals that were similar differed from
island to island.
Finches
Darwin’s Finches
Darwin wondered…Had these
birds evolved from a similar
species? From one common
ancestor?
?
?
?
?
Darwin’s finches are an
example of evolution as well
as adaptation.
An Adaptation is any
inherited trait that gives an
organism an advantage in
it’s particular environment.
Artificial Selection
(Breeding)
Natural Selection:
Members of a species
that are best suited to
their environment survive
and reproduce at a higher
rate than other members
of the species.
Natural Selection:
Members of a species
that are best suited to
their environment
survive and
reproduce at a higher
rate than other
members of the
species.
The process of natural selection
1. Over production: When a plant or animal reproduces, it usually makes more
offspring than the environment can support. Some will die of disease or due to
predation. Others will live to adulthood and even fewer will successfully
reproduce and pass on their genetics.
2. Variation: Within a species there are natural differences, or variations, in traits.
Many of these differences among individuals result from differences in the
genetic material of the fish. Sometimes a mutation occurs causing new variation
to come about. As individuals with the new variation reproduce, the trait gets
passed on to its offspring. *Therefore, genetic variations are passed on from
one generation to the next.
3. Adaptation: Sometimes a mutation occurs that makes an individual better able
to survive than other members of the group. This would be an adaptation that
gives an organism an advantage in its particular environment. Helps it to survive
illness or predators…or helps it to hunt more efficiently.
4. Selection: Individuals with a beneficial adaptation are most likely to survive long
enough to reproduce. As a result, the adaptation becomes more common in the
next generation. As this process repeats from generation to generation, more
members of a species show the adaptation.
Adaptation
Selection
A New Species Arises
4.Selection: Individuals with a beneficial adaptation are most
likely to survive long enough to reproduce. As a result, the
adaptation becomes more common in the next generation. As
this process repeats from generation to generation, more
members of a species show the adaptation.
Speciation:
Is the evolution of new
species from an
existing species.
Isolation: The separation of two populations of the
same species by a physical barrier, such as a
mountain or body of water. Geographical isolation
may ultimately lead to the populations becoming
separate species.
It is not the strongest
of the species that
survives, nor the most
intelligent that
survives. It is the one
that is most adaptable
to change.