Download Evolution Part 2

- Evolution -
- Evolution The English noun evolution (from Latin
ēvolūtiō "unfolding, unrolling") refers to any
kind of gradual change.
- Evolution “nothing in biology makes sense except in the
light of evolution”
Theodosius Dobzhansky (1900-1975)
Darwin’s Return
Darwin’s Return
• Darwin returned to England in
1836 and brought the
specimens he had collected
from around the world.
Darwin’s Return
• Darwin returned to England in
1836 and brought the
specimens he had collected
from around the world.
• He made some
remarkable
discoveries about
some of these
specimens.
Darwin’s Return
• He made some
remarkable
discoveries about
some of these
specimens.
Darwin’s Return
• He made some
remarkable
discoveries about
some of these
specimens.
• One was that all the
birds he had
collected on the
Galapagos turned
out to be finches.
Darwin’s Return
• There were other
examples too, of
animals found on the
Galapagos, but
nowhere else.
• He made some
remarkable
discoveries about
some of these
specimens.
• One was that all the
birds he had
collected on the
Galapagos turned
out to be finches.
Darwin’s Return
• There were other
examples too, of
animals found on the
Galapagos, but
nowhere else.
• He began to work on
making sense of these
findings.
Darwin’s Return
• There were other
examples too, of
animals found on the
Galapagos, but
nowhere else.
• He began to work on
making sense of these
findings.
• He spent the next
23 years putting
together his theory.
Darwin’s Return
• He spent the next
23 years putting
together his theory.
• In 1859 he
published On the
Origin of Species.
The Big Idea
The Big Idea
• Response to Darwin’s
work was very divided.
The Big Idea
• Response to Darwin’s
work was very divided.
• Some people thought it
was brilliant, while
others were strongly
opposed.
The Big Idea
• Response to Darwin’s
work was very divided.
• Some people thought it
was brilliant, while
others were strongly
opposed.
• A situation that is not
that different from
today.
The Big Idea
• What exactly is in that book anyway?
What the heck!
• Darwin’s Theory of Evolution can be summed
up as follows:
The Big Idea
1) Individual organisms differ,
and some of this variation is
heritable.
The Big Idea
1) Individual organisms differ,
and some of this variation is
heritable.
The Big Idea
1) Individual organisms differ,
and some of this variation is
heritable.
• Darwin noticed that animal
breeders used heritable
variation to produce animals
with desirable characteristics.
The Big Idea
1) Individual organisms differ,
and some of this variation is
heritable.
• Darwin noticed that animal
breeders used heritable
variation to produce animals
with desirable characteristics.
• Called Artificial Selection,
nature provided the variation,
and humans selected the
variations they found useful.
The Big Idea
• Darwin was convinced a
process like artificial selection
was at work in nature.
The Big Idea
• Darwin was convinced a
process like artificial selection
was at work in nature.
• Darwin recalled the work of
Malthus on population growth
– having too many offspring to
all survive would result in a
competition for resources.
The Big Idea
• Darwin was convinced a
process like artificial selection
was at work in nature.
• Darwin recalled the work of
Malthus on population growth
– having too many offspring to
all survive would result in a
competition for resources.
• Which ones, Darwin wondered,
would be the most likely to
survive and reproduce?
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
• This was Darwin’s Big Idea –
that nature will select the
characteristics that make the
organism the “most fit”.
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
• This was Darwin’s Big Idea –
that nature will select the
characteristics that make the
organism the “most fit”.
• He called this Natural Selection
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
• This was Darwin’s Big Idea –
that nature will select the
characteristics that make the
organism the “most fit”.
• He called this Natural Selection
• Only organisms most fit for their
environment will pass on their
genes.
The Big Idea
2) Individuals best suited to their
environment survive and
reproduce most successfully.
• This was Darwin’s Big Idea –
that nature will select the
characteristics that make the
organism the “most fit”.
• He called this Natural Selection
• Only organisms most fit for their
environment will pass on their
genes.
The Big Idea
3) Species alive today
“descended with
modification” from species
that lived in the distant
past.
The Big Idea
3) Species alive today
“descended with
modification” from species
that lived in the distant
past.
• This process, unites all
organisms on Earth into a
single tree of life.
The Big Idea
3) Species alive today
“descended with
modification” from species
that lived in the distant
past.
• This process, unites all
organisms on Earth into a
single tree of life.
Video
The Big Idea
3) Species alive today
“descended with
modification” from species
that lived in the distant
past.
• This process, unites all
organisms on Earth into a
single tree of life.
Video
Video 2
The End of Part II