Download Evolution Notes

Evolution Notes
Or, a scientific explanation
for the diversity of life on our
planet.
 Organisms have characteristics that
help them survive well in their
environment.
Example: Many animals have skin
or fur that is the color of their
surroundings or have thick fur in a
very cold environment, etc.
Adaptation

These characteristics that help
organisms survive (and reproduce)
in their environment are called
adaptations.
Example:
Modern whales
have a lot of
blubber that
helps them stay
warm in a very
cold ocean!
Mmm,
toasty warm
Species

A species is a group of organisms that can
mate with one another to produce fertile
offspring (offspring that can have more
offspring).
Example: A horse and a donkey are each fertile, but if they
have an offspring together, the offspring is NOT fertile
(meaning it cannot produce another generation.)
Question: What is the offspring of a
horse and a donkey called?
+
=
Fertile Horse
Fertile Donkey
Sterile Mule
Female Tiger
Male Lion
+
Female Liger or Male Liger
=
Male Tiger
Female Lion
+
Tigons
=
Evolution


Evolution is change over time.
A species can go through so many changes
that it becomes another species.
Example: If all living
things share a
common ancestor,
then each species
today has gradually
developed different
features to distinguish
the species.
How do we know about
evolution?
There are 6 lines of evidence for
evolution
1.
2.
3.
4.
5.
6.
Fossil Record
Biogeography
Vestigial Structures
Morphology
Modern Genetics
Drug Resistance
Diversity

Diversity is a measure of the
number of species an area
contains.
FACT: Tropical regions have much higher diversity
(or more different species) than cold, polar regions.
Squaaak! Life is
good with all
these folks around!
Jeesh,
it’s hard
work living
up here.
Fossil Record

The fossil
record shows
evidence of
past living
things found in
layers of the
earth’s crust.
Not every organism that
scientist think existed
can be found as fossils
because most of the
time dead organisms
don’t form fossils.
Fossil Record
From the fossil record,
scientists can see that
life has not always been
the same.
Example: This record shows
that a certain tree-dweller
becomes two species!
Vestigial Structures

A vestigial structure is a part
of an organism that was
useful in the past but now is
not.
Example: For example, whales
have small bones which seem to
have become smaller over time.
These bones may be remnants of
hind legs which whales no longer
have.
Question: What do
humans have that we
no longer use?
Similar Anatomy


Looking at the overall body and similar
body parts
Compare eyes to eyes or ears to ears
Whale Eye
Frog Eye
Dog Eye
Similar Skeletons

When we
compare the
skeletons of
different
animals, the
structure of
their bones
look very
similar.
Similar DNA

DNA of organisms that are
related (have evolved from one
another) is similar.
The DNA of closely related
organisms is more alike than
organisms that are not
closely related.