Download change over time

CH.15 DARWIN’S THEORY OF EVOLUTION
15.1 Life’s Diversity
1. Evolution – change over time; the
process by which modern organisms
have
descended
from
ancient
organisms. (scientific theory)
2. Voyage of the Beagle:
Charles Darwin – joined the H.M.S. Beagle
in 1831 and made observations that led
him to a hypothesis about the way life
changes over time.
3.Fossils – Darwin collected fossil evidence
- the remains of ancient organisms. Some
of those fossils resembled organisms that
were still alive. Others looked unlike any
creature he had ever seen.
4.Galapagos Islands – He was
fascinated by the land tortoises, marine
iguanas and finches.
15.2 Ideas That Shaped Darwin’s Thinking
Lamarck – a French naturalist.
a. In 1809, he published a hypothesis
that by selective use or disuse of
organs, organisms acquired or lost
certain traits during their lifetime.
b. These traits could be passed through
offspring and eventually leads to
change in a species.
Ex/ Ancestors of birds acquired an urge to
fly. Over many generations, the birds kept
trying to fly and their wings increased in
size and became more suited to flying.
-Use and Disuse – organisms can alter the
size or shape of particular organs by using
their bodies in new ways.
c. Ex/ Trying to use their limbs for flying,
eventually transformed the limbs into
wings. If a winged animal did not use
its wings, the wings would decrease in
size over generations and finally
disappear.
-Inheritance of Acquired Traits – acquired
characteristics could be inherited. All the
changes made, it would pass those
changes to its offspring.
d. Ex/ If you spent your lifetime lifting
weights, your children would inherit
big muscles.
Problem: Answer the following questions:
In the 1800s, the Irish solved their
problem of feeding a growing population
by planting potatoes. Specifically, they
planted the "lumper" potato variety. And
since potatoes can be propagated
vegetatively, all of these lumpers were
clones, genetically identical to one
another.
The lumper fed Ireland for a time, but it
also set the stage for human and
economic ruin. Evolutionary theory
suggests that populations with low
genetic variation are more vulnerable to
changing environmental conditions than
are diverse populations. The Irish potato
clones were certainly low on genetic
variation, so when the environment
changed and a potato disease swept
through the country in the 1840s, the
potatoes (and the people who depended
upon them) were devastated.
1) In 1846, 100% of the potato crop was
killed by a single fungus. Why?
2) Why does cloning compromise the
potato’s genetic variation?
3) How would the fungus affect a wild
population of potatoes? Why?
15.3 Genetic Variation
1. Darwin – how could the wren, warblers
and blackbirds all be descendents of a
finch?
a. His idea abandoned the idea that a
species is perfect and unchanging
and argued that natural variation
explained the mechanism of change.
2. Natural Variation – the differences
among individuals of a species, found in
all types of organisms. Ex/ Antibiotics +
Bacteria, Ex/ Humans + Bubonic Plague
3. Artificial Selection – or selective
breeding, is when breeders use variation
to improve crops and livestock.
Ex/
Cows + milk
a. Q – Give an example of how we use
selective breeding today.
4. Struggle for Existence – artificial
selection works in nature. Ex/ predators
vs. prey
5. Survival of the Fittest – the ability of an
individual to survive and reproduce in its
specific environment (adaptations).
6. Adaptations
–
is
any
inherited
characteristic
that
increases
an
organism’s chance for survival.
Ex/
porcupines or feathered seeds
7. Genetic Variation – each individual
differs from other members of its species,
unique advantages and disadvantages.
8. Natural Selection – because some
species do better in their environment,
they go on to reproduce and fit in their
environment.
a. Give an ex/ of genetic variation:
9. Common Descent – All species – living
and extinct – were derived from
common ancestors. A single “tree of life”
links all living things.
Evidence of
Evolution
includes
The fossil
record
Geographic
distribution of
living species
Homologous
body
structures
Similarities
in early
development
which is
composed of
which
indicates
which
implies
which
implies
Physical
remains of
organisms
Common
ancestral
species
Similar genes
Similar genes
10. Fossil Record – the evidence of
physical remains
11. Geographic Distribution – similar
animals in different locations that are
from different times of descent. Ex/
12. Homologous structures – anatomical
similarities among the body parts of
animals with backbones.
a. Vestigial Organs – Ex/ Whale
b. Embryology – early stage embryos
Ex/ chickens, turtles, rats look similar.
Beaver
NORTH
AMERICA
Beaver
Muskrat
Muskrat
Beaver and
Muskrat
SOUTH
AMERICA
Coypu
Capybara
Coypu and
Capybara
Capybara
Coypu
Ex/ Which two are
the closest in relation?