Evolution Notes

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Evolution Notes

• Or, a scientific explanation for the diversity of
  life on our planet.

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• 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.
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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
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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?
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Fertile Horse
Fertile Donkey
Sterile Mule
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Female Tiger
Male Lion


Female Liger or Male Liger
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Male Tiger
Female Lion


Tigons
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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.
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How do we know about evolution?
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There are 6 lines of evidence for evolution

1. Fossil Record
2. Biogeography
3. Vestigial Structures
4. Morphology
5. Modern Genetics
6. Drug Resistance

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Diversity

• Diversity is a measure of the number of species
  an area contains.

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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, its hard work living up here.
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Fossil Record

• The fossil record shows evidence of past living
  things found in layers of the earths crust.

Not every organism that scientist think existed
can be found as fossils because most of the time
dead organisms dont form fossils.
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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!
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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.
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Question What do humans have that we no longer
use?
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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
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Similar Skeletons

• When we compare the skeletons of different
  animals, the structure of their bones look very
  similar.

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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.