6. A long time ago, a small flock of sparrow-like birds called
finches were
blown out to sea by a fierce storm. They lost their bearings but
flew on in search of the mainland, going further and further out
to sea. At the point of exhaustion, 600 miles from home, they
spotted a speck of land - an island in the middle of the sea. They
were saved and could rest, drink and feed before returning
home. But this island was perfect: it had abundant seeds and
other food, plenty of shelter, nesting sites and (amazingly) no
predators or other birds to compete with.
7. Life was much harder on the mainland. There was no
need for the birds to move on. Their numbers grew -
until they became just a bit too numerous for the little
island. Some found it hard to find enough food for
themselves or their offspring, and young birds were
driven away from areas where food was available. Some
birds were forced to fly across the sea to nearby islands.
There, they found new territories, also with no
predators or other birds to compete with.
8. As the plants and their seeds were just a little
different on each island, some birds were better than
others at finding and eating the new food sources. Birds
which could break open fruits and eat the seeds survived
well enough to produce lots of babies. Eventually, after
a very long time, all the islands became occupied by
these birds but the finches on each island were slightly
different.
9. 1. Explain why it is questionable that more than one
flock of birds would find the islands in this way at
the same time.
2. Suggest two possible reasons why there were no
predators on the island.
3. Why were there no other birds to compete with?
(see Q1)
4. Why might some finches survive better than
others on the same food sources?
5. Why were the finches slightly different on each
island?
10. History of Evolutionary Thought
Catastrophism (Werner/Cuvier)
States that the earth and geological
events had formed suddenly, as a
result of some great catastrophe.
11. History of Evolutionary Thought
Uniformitarianism (Hutton/Lyell)
Idea that the earth has always
changed in uniform ways and that the
present is the key to the past
13. Jean-Baptiste Lamarck (1744-1829)
Developed one of the first
theories on how species
changed
Concluded that organisms of
higher complexity had
evolved from pre-existing,
less complex organisms.
Lamarck’s Theories on Evolution
14. Jean-Baptiste Lamarck (1744-1829)
Lamarckism, a theory of evolution
based on the principle
that physical changes in
organisms during their lifetime—
such as greater development of
an organ or a part through
increased use—could be
transmitted to their offspring.
Lamarck’s Theories on Evolution
15. Lamarck’s Theories on Evolution
Theory of Need Theory of Use
and Disuse
Theory of
Acquired
Characteristics
17. Lamarck’s Theories on Evolution
Organisms change
because they need to.
For an organism to
evolve a structure, it
must need the
structure
Theory of Need
23. Lamarck’s Theories on Evolution
If you don’t use it, you lose
it!
Organisms develop
specialized characteristics
by the use and disuse of
organs
Theory of Use and Disuse
25. Lamarck’s Theories on Evolution
If parent acquires a
body structure during
its lifetime, it could
pass on that
characteristic structure
to its offspring.
Theory of Acquired Characteristics
26. 1. Petals on flowers
2. Corset
3. Frequent exercise
4. Tails of mice
Disproving Lamarck
27. Charles Darwin (1809-1882)
Proposed an entirely different
mechanism to account for the
evolution of species
His theory of evolution by
natural selection became the
foundation of modern
evolutionary studies
Theory of Natural Selection
31. Darwin was able to see 13
varieties of finches, which
varied in size & shape,
from island to island.
It took him 20 years to
organize the data.
Darwin’s finches
36. Individuals within a
population with the
most favorable traits
for an environment
survive and pass on
those traits.
Natural Selection
SURVIVAL OF THE FITTEST!
37. Organisms tend to
over reproduce
Theory of Natural Selection
Species Overproduction
38. There is a struggle
of existence and
the survival of the
fittest
Living space and
food are limited
Theory of Natural Selection
Competition
39. No two individuals
are the same
Plants and animals
of the same species
differ in size,
strength and
adaptive structures
Theory of Natural Selection
Variation
40. It is a process of
becoming better
suited to the
environment.
It improves an
organism’s chance
of survival
Theory of Natural Selection
Adaptation
49. Before the industrial
revolution in Britain,
most peppered moths
were of the pale
variety & were well
camouflaged against
the pale birch trees
that they like to sit on.
Theory of Natural Selection
Peppered Moths
50.
51. Airborne pollution mottled
the birch tree bark with
soot, and now the mutant
black-peppered moths
blended better against the
darkened bark, while the
white variety became much
more vulnerable to
predators.
Theory of Natural Selection
Peppered Moths
Catastrophism was a theory developed by Georges Cuvier based on paleontological evidence in the Paris Basin. Cuvier was there when he observed something peculiar about the fossil record. Instead of finding a continuous succession of fossils, Cuvier noticed several gaps where all evidence of life would disappear and then abruptly reappear again after a notable amount of time. Cuvier recognized these gaps in the fossil succession as mass extinction events. This led Cuvier to develop a theory called catastrophism. Catastrophism states that natural history has been punctuated by catastrophic events that altered that way life developed and rocks were deposited.
Procedure:
Observe the set of footprints in the diagram.
Try to tell a story about the different events.
Predict what can probably happen at the end of the diagram
In Diagram 1, how many sets of footprints are there? Based on the size of footprints, describe the organisms.
2. In what directions are the footprints going?
3. Describe or predict what is happening in Diagram 3. In Diagram
