Transcript Theory of Evolution

Theory of Evolution
Stated Clearly: “What is Evolution.”
http://www.youtube.com/watch?v=GhHOjC4oxh8
EVOLUTION: REFERS TO THE PROCESS BY WHICH SPECIES OF
ORGANISMS CHANGE OVER TIME OR THE PROCESS OF
BIOLOGICAL CHANGE BY WHICH DESCENDANTS COME TO DIFFER
FROM THEIR ANCESTORS
CAROLUS LINNAEUS
-Came up with a system to
organize and name all of
the different known types
of organisms, or species
-Species: a group of
organisms that can
reproduce and have fertile
offspring
-Grouped organisms
according to physical
similarities & also showed
evolutionary relationships
Fossil: the remains or evidence of
a once-living organism.
THEORIES OF GEOLOGIC CHANGE
1. Catastrophism: the idea that past natural
disasters-like floods and volcanic eruptionsshaped landforms, and caused species to
become extinct in the process
2. Gradualism: the idea that landforms were
shaped by very slow changes over a long
period of time, and not by natural disasters
3. Uniformitarianism: the idea that the same
processes that shaped landforms in the past
also shape landforms today
WHAT DID THE GEOLOGISTS SAY?
Geology: the
scientific study of
Earth and its
features
•Charles Lyell: proposed
uniformity - the idea that events
in Earth’s past are similar to those
happening now
•Hutton and Lyell argued that the
earth is many millions of years
old because:
a) layers of rock take time to form
b) processes such as volcanoes and
earthquakes shaped the earth
and still occur today
LAMARK
THEORY OF ACQUIRED CHARACTERISTICS
•Lamark said organisms
acquired traits by using their
bodies in new ways
• These new characteristics were passed
to offspring
•Proposed the principle of
use and disuse
Lamark is well
known for being
WRONG .
MALTHUS
Reasoned that if the
human population
continued to grow
unchecked, sooner or later
there would be
insufficient living space
and food for everyone
*Remember it: MALTHus
said there would be too
many MOUTHS to feed.
LOTS OF OTHER SCIENCES CONTRIBUTED TO THE
THEORY OF EVOLUTION
Anatomy
Embryology
Paleontology
Biochemistry
Molecular Biology
BUT MOST IMPORTANT
WAS HEREDITY AND
GENETICS!!!
CHARLES DARWIN (1809-1882)
SAILED AROUND THE WORLD 1831-1836
WHAT DID DARWIN’S
TRAVELS REVEAL?
The diversity of living species
was far greater than anyone
had previously known!!
He was amazed by the variation
among similar species. Variation
means the differences in the
physical traits among individuals
in a group of organisms.
These observations led him to
develop the theory of evolution!!
HOW DID TORTOISES AND BIRDS DIFFER AMONG
THE ISLANDS OF THE GALAPAGOS?
-Each island had its own type of
tortoises and birds that were
clearly different from other
islands.
-Why? Species were adapting to
their environment. Adaptation is a
feature that allows and organism
to better survive in its environment.
-What did they have in common?
Ancestry
-What was different? Ecosystem,
beak shape (finches) and diet
GALAPAGOS TURTLES
Reproductive isolation: an inability of
organisms to interbreed due to geographic
barriers.
Tortoises differed depending on
where they lived. Dome-shaped
shells and shorter necks lived on
wet, highly vegetated islands.
Tortoises with curved shells and
long necks lived on drier islands.
EVOLUTION IS A THEORY – NOT A LAW LIKE
GRAVITY!
•Evolution is a well
supported explanation
of phenomena that have
occurred in the natural
world
•A theory in science is a
well tested hypothesis,
not just a guess
DARWIN FINALLY
PUBLISHED HIS IDEAS IN
1859
•Other naturalists were
developing the same
theory that Darwin
did.
•Darwin decided to
publish even though
he was afraid of the
Church’s reaction to
his book. He wanted
to get credit for his
work.
NATURAL
SELECTION
The idea that
organisms with
favorable variations
for their environment
survive, reproduce,
and pass those
variations on to the
next generation.