Catalyst
Why do some individuals die
while others survive and
reproduce?
Explain how photosynthesis and
cellular respiration are related
Explain the function of stoma
Ideas
that
shaped
Darwin
From 1831-1836, Charles
Darwin traveled on H.M.S.
Beagle. He collected specimen of animals, plants, and fossils. Darwin saw patterns in how
kinds of animals and plants differed, patterns suggesting that species change over time and give rise to new species.
Finches
Thomas Malthus: if there are
too many individuals, there will not be enough resources
Voyage of the HMS Beagle
Ideas that
shaped
Darwin
James Hutton and
Charles Lyell determined the world was older than anyone thought
Jean-Baptiste Lamark
(1809): Based on how much an organism uses their body parts, they
will acquire or lose them over their life and then pass down these traits
WRONG, but he did
LaMarckian vs. Darwinian
view
LaMarck
in reaching higher
vegetation giraffes
stretch their necks & transmits the acquired longer neck to
offspring
Darwin
giraffes born with longer necks
survive better & leave more offspring who inherit their long necks
Ideas
that
shaped
Darwin
Artificial Selection:
different traits are produced naturally, and then people
selected the
variations they found useful. If people can do this, why couldn’t nature?
VOCAB
An adaptation is a trait
that distinguishes one
individual from
another and helps the
individual survive and
reproduce
Fitness is the ability for
an individual to
Evolution
Evolution is any change across generations in the inherited
characteristics of an organism
Evolution is a change in gene
frequency, and therefore the traits, of a species over time
Evolution is a result of
differential reproductive success
Today we are talking about how organisms adapt to their
environment. WE ARE NOT
Theory of Evolution by Natural Selection
1859 publication of Charles Darwin’s
On Origin of Species.
Proposed that
organisms alive today
“descended” from a
common ancestral
species.
Requirements for
Evolution by Natural Selection
1. Individuals
of a
population
2. All species produce more offspring than the
environment can support (overpopulation).
Houseflies produce so
many offspring in a single season, if they all survived they would cover an area the size of Germany to a depth of 47 feet.
3. This
overpopulation
leads to a struggle
for existence
among individuals
of a population,
with only some
surviving each
generation.
4. Survival of the fittest
Those individuals with
inherited
characteristics best fit
to their environment
are likely to leave more
offspring than less fit
individuals. These
individuals are selected
for by nature
Evolutio
n
Evolution is a direct result of differential
reproductive success
Organisms that inherited better genes are
more likely to survive and reproduce.
Organisms that inherited worse genes are less likely to survive and reproduce.
Over time, a higher percent of individuals
will have better genes – this is evolution!!!
Environmental limitations cause natural
Evolution by Natural
Selection
Natural selection is the idea that only the
organisms that have the traits to deal with environmental challenges survive. The
environment selects which organisms will survive and reproduce. These reproducing
18 Canadian squirrels were released at
the National Zoo during the presidency of Theodore Roosevelt.
Scientists say the black variety now
comprises 5 to 25 percent of the squirrels in some neighborhoods.
In winter, their dark coats allowed
them to retain heat from sunlight, leaving them less desperate for warmth than their lighter-colored cousins.
"It shows the spread of a gene within a
population," said Richard W. Thorington Jr., a Smithsonian Institution researcher working on a book that includes a
Galapagos
Recent volcanic origin most of animal species on the
Galápagos live nowhere else in world, but they resemble species living on South
American mainland.
Finch? Sparrow?
Woodpecker? Warbler?
Darwin found… birds
Finch? Sparrow?
Woodpecker? Warbler?
Collected many
Collected many
different birds on the
different birds on the
Galapagos Islands.
Galapagos Islands.
Thought he found
Thought he found
Darwin was amazed to find out:
All 14 species of birds were finches…
Finch? Sparrow?
Woodpecker? Warbler?
Finch? Sparrow?
Woodpecker? Warbler?
But Darwin found… a lot of
finches
Large Ground
Finch
Small Ground
Finch
Warbler Finch Veg. Tree Finch
But
there is only
one
species of finch on the
mainland!
How didone species of finches become
Tree Thinking
Large-seed eater? Small-seed eater?
Warbler? Leaf-browser?
Large Ground Finch
Small Ground Finch
Correlation of species to food source
Rapid speciation:
Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous tree finch Vegetarian tree finch Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground finch Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finc hes G ro un d fin
ch es
Darwin’s finches
Differences in beaks
associated with eating different foods
____________________________________________________
Evolution
Populations evolve NOT individuals – occurs over long periods of time
Natural selection causes differential success in reproduction. This is
survival of the fittest
Using our knowledge of genetics, we can say that evolution is a
change in gene frequency. The best genes get passed on (remember,
Evolution
Evolution is only possible
because of genetic variation– genetic variation causes
offspring to have different traits and therefore allows natural selection to occur!
The greater the genetic
NOTES:
Organisms are not perfectly
adapted to present environment –
panda bear (Red Queen Effect)
Selection is constrained by
genome. The panda’s “thumb”.
Natural selection causes organisms
What is evolution?
Describe Darwin’s theory of
evolution by natural selection IN
YOUR OWN WORDS
Explain how natural selection might
have produced modern giraffes
from short-necked ancestors
