Transcript Presentation

Section 5.1
{
Change Over Time





Adaptation: A characteristic that helps an organism
survive and reproduce in its environment.
Species: A group of organisms that can mate with one
another to produce fertile offspring.
Evolution: The process in which populations
gradually change over time.
Fossils: The remains of imprints of once-living
organisms, sometimes found in layers of rock.
Fossil Record: A timeline of life that is known as
indicated by fossils found in the Earth’s crust.
Vocabulary


After reviewing the vocabulary terms for this
section, what are some things you already
know about this section?
Are there any topics of interest or things you
remember from other classes?
What do you already
know?




Different organisms have different characteristics, or
adaptations, that allow them to survive in their
habitat (find food, protect itself, and reproduce).
Living things with similar characteristics may be
members of the same species.
There are many species of organisms on Earth today,
but have they always existed? What existed before
now that no longer exists? What will exist in the
future?
Scientists have evidence that Earth and the species
on Earth have change a great deal, or evolved, over
time.
Differences Among
Organisms . . .



Scientists estimate that the planet is over 4.6 billion
years old . . . Have the species that exists today
always been here? Explain your thoughts . . .
Evidence of changes in species over time can be
found in fossils found deep within the Earth’s
surface.
By studying fossils, scientists are able to create a
timeline of life (known as the fossil record). Fossils
found deeper in the Earth’s surface are not quite as
similar to modern day organisms as newer fossils.
Evidence of Changes Over
Time . . .



The fossil record provides evidence about the
order in which species have existed.
Scientists observe that all living organisms have
characteristics in common and inherit
characteristics in similar ways . . . So, scientists
believe that living species descended from
common ancestors.
Scientists examine fossil records to figure out the
relationship between extinct and living organisms.


EXAMPLE: Scientists believe that whales and some
types of hoofed mammals have a common ancestor.
Scientists use this evidence to sketch out a “tree of
life” that includes all known organisms.
Evidence of Ancestry . . .

Case Study: Evolution of the Whale


Scientists believe that the ancient ancestor of
whales was probably a mammal that spent time
on land and in water.
Scientists have studied the characteristics of
ancient four-legged mammals and, though
modern day whales do not have hind limbs, they
have tiny internal hip bones. This evidence
supports that whales may have an ancient land
dwelling ancestor. (see p. 112-113 in your text)
Examining Organisms . . .

Scientists can study and compare organisms’
DNA to determine how traits have changed
over time.


HYPOTHESIS: If species that have similar traits
evolved from a common ancestor, the species
will have similar genetic information.
Scientists also study skeletal structures of
organisms and compare them.


If you look at the skeletal structure of a dolphin
flipper, bat wing, human arm, and cat leg, you
can see how there are similarities.
Scientists believe that skeletons of organisms
changed over time to perform different
functions.
Comparing Organisms . . .

http://www.youtube.com/watch?v=9R8hpPY_9
kY&list=PL6090C98C77B3C295
Tree of life . . .

http://www.pbs.org/wgbh/evolution/educators/
lessons/lesson3/act2.html
Small Group Activity . . .