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Charles Darwin. born in Shrewsbury, England, in 1809. studied medicine at Edinburgh University (1825-1827) where the sight of blood and surgery without anesthetics repulsed him. studied to become a clergyman at Cambridge University (1827-1831). - PowerPoint PPT Presentation
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studied medicine at Edinburgh University (1825-1827) where the
sight of blood and surgery without
anesthetics repulsed him
studied to become a clergyman at Cambridge University (1827-1831)
born in Shrewsbury, England, in 1809
After Cambridge, Charles was
recommended for a surveying trip on the
HMS Beagle.
He sailed aboard the Beagle for 5 years,
working as a naturalist.
This voyage lasted from 1831 to 1836.
The Beagle sailed around the world.
At the time Darwin made his trip, the majority of
people believed the Earth and all of its forms of life had been created only a few thousand years in
the past.
People also believed in fixity of species; in other words, species never changed.
After careful observation and
study of new scientific
discoveries, Darwin began to think otherwise.
People also believed that the Earth had not changed during those few thousand years.
The first dinosaur to be described scientifically was Megalosaurus by William Buckland in 1824.
Darwin was influenced by geologist James
Hutton’s writings that described geologic
forces he thought had changed and were still
changing the earth.
Hutton proposed that the Earth had to be
much more than a few thousand years old.
The Father of Geology
Darwin was also influenced by
geologist Charles Lyell who wrote
Principia Geologica.
Lyell’s book proposed that tremendous
geologic processes had shaped the Earth
such as seen in volcanoes active in
the present.
On the voyage, Darwin noticed
that everywhere he went, the animals
and plants differed vastly.
Patterns in the species suggested that the
species had changed over time and had given rise to new and different
species.
The Galapagos Islands lie 500 miles west of Ecuador in the Pacific Ocean,
directly on the equator.
Many of Darwin’s conclusions were
based on observations of
wildlife in the Galapagos Islands.
“Galapagos” means turtle.
What it must have been like to be Darwin…
Darwin noticed on these islands,
there were several types of finches.
In particular, Darwin observed something odd
about the finches: they all
looked like a bird he had seen
on the South American continent.
Darwin wondered if the birds and other animals had been created to match their
environment, why didn’t these birds look like the birds of the African continent, since the
environments of both the Galapagos and Africa were similar.
Darwin guessed that some of the birds
from South America migrated to the
Galapagos.
Once on the islands, the birds must have
changed over the years.
This would explain the numerous species of birds present.
woodpecker finch
cactus finch
large ground finch
Darwin called this…
or
(change in species over time)
Darwin concluded:Each species has descended, with changes,
from other species over time.
Descent With Modifications
Malthus was a British social scientist who made these observations about
humans:
People have more children than are able to survive.
There are built-in population checks: disease, famine, and war.
Darwin based his theory on his own observations
and the writings of Thomas Malthus.
Darwin extended these principles to biology, which
helped him form his theory of…
…or Survival of the Fittest.
Five basic components of
1. All species have genetic variation.
Every species is different, even within itself.
Look around you…are you all the same?
2. Organisms produce more offspring than can survive. Many that survive do not produce offspring.
The female green sea turtle lays a clutch of about 110 eggs. She may lay several clutches.
It is likely that less than 1% of the hatchlings will ever reach sexual maturity.
3. Since more organisms are produced than can survive, there is competition (struggle for existence).
Competition exists WITHIN and AMONG species.
foodWithin and Among Species for
And Within a Species for
water
mates
shelter space
The constant struggle for survival is affected by short-term natural disasters. (drought, fires, floods, snowstorms, hurricanes, and tornadoes)
The constant struggle for survival is also affected by long-term changes in the environment. (ice ages, biome shifts, etc)
4. Survival of the fittest Some organisms are more suited to their environment as a result of variations in the species.
Fitness: the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptations.
He who spreads the most genes wins!1st
Individuals that are fit to their environment survive and leave more offspring than those who aren’t.
5. Descent with modification: Living species today are descended with modifications from common ancestral species that lived in the past.
Over time, genes for less favored characteristics will be eliminated from the gene pool.
Example: giraffes and their increasingly longer necks.
Characteristics of fit individuals increase in a population over time.
Natural Selection: Survival of the Fittest
the variation exists first.
An adaptation is any inherited characteristic (a genetic variation) that can increase an organism’s chance of survival.
the environment changes.
a variation may give an advantage to survive environmental change.
An organism does not change because of need or desire to survive. The organism either already has the variation that enables it to survive or it dies.
As the environment changes, organisms must have variations that allow them to survive (adapt) to those changes or die
If an entire population of a species cannot adapt, that species becomes extinct.
There have been at least 5 MASS extinctions during Earth’s history where a huge % of the living species were destroyed
At least one of these has been
attributed to meteor impact and it’s consequences.
Davis, Donald E. “Meteor Impact”. (Also public domain from NASA.) No date. Online image with permission. Dinosaurs and Their Extinction. June 10, 2004. <http://www.donaldedavis.com/PARTS/DDDINOS.html>
“Snow Alaska”. No date. Online image. Public Domain. Mineral Management Service. June 10, 2004. GeekPhilospher.com <http://geekphilosopher.com/bkg/snowAlaskaIce.htm>
“Allosaur”. No date. Online image. Public Domain. Dinosaur National Monument. National Park Service. June 10, 2004. http://www.nps.gov/dino/index.htm