Download Artificial Selection - Northwest ISD Moodle

Title your page:
Natural Selection and
Selective Breeding Notes
How Traits Change Over Time
Selective Breeding:
• The slide background
color changes when the
concept changes.
– Blue: Selective Breeding
– Orange: Natural Selection
• Highlight or put a box
around those two words
to separate the two
concepts in your notes.
Natural Selection:
DO NOT write this box for Natural Selection
until you have written down all notes for
Selective Breeding. These notes will start on
slide 9 as designated by the orange
background.
Selective Breeding:
The intentional mating of two organisms in an attempt
to produce offspring with desirable characteristics.
– Humans influence genetics
– A person “selects” organisms to breed favored traits
– Selective Breeding is often benefiting only the human and
does NOT provide a survival advantage for the animal.
List the following as
EXAMPLES of Selective Breeding
You do NOT need to draw the pictures
You’ll notice each
example shows that a
HUMAN was responsible
for the breeding process.
3. GARDENERS
can breed red and
white flowers to
produce pink
flowers
1. BREEDERS breed dogs to be friendly or aggressive.
They can be bred to produce various sizes of dogs
4. JOCKEYS can
breed horses for
increased speed.
2. FARMERS can
breed cows to
produce more milk
and to have more
muscle providing
more meat.
5. SCIENTISTS can breed
two species as an
experiment to ‘create’ a new
species .
(Zebra + Donkey = Zonkey)
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ONLY
Careful
breeding of
food crops like
corn and wheat
have resulted in
plants that yield
more food per
acre.
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If you wished to
breed the fastest
racehorses, how
would you do it?
You would probably mate your fastest male
and female horses knowing their offspring
should also be fast. If you continued to breed
only the fastest horses generation after
generation, soon you will have horses ready to
race in Churchill Downs.
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If you wished to breed the prettiest
guppies, how would you do it?
By only selecting the most colorful guppies and
those with the longest tails, then breeding them
generation after generation.
wild guppies
Guppy which has been
selectively bred.
In essence, when humans selectively breed organisms
for certain traits, they are selecting certain genes (a
segment of DNA that contains the code for a trait).
Natural Selection:
Plants and animals that can adapt to changes
in their environment are able to survive and
reproduce while those that cannot adapt do
not survive
-Natural Selection is a synonym to “Survival of
the fittest” and refers to a competition among
species for the same resources.
Main Idea of Natural Selection
“Only the BEST
survives. If it is not
the best, it will DIE”
Write this phrase in BOLD in your notebook.
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While in the Galapagos Islands in the Pacific
Ocean, Charles Darwin wondered about the
origins of the many variations of plants and
animals he collected there. He wondered if nature
could select for certain traits in the same way that
man selects for certain traits.
Can you find the animals in the pictures below?
Natural Selection
• Natural selection is possible
because of genetic variation
among individual organisms within
a population.
• Over generations, traits that
enhance survival of a species are
selected over those that do not.
– When all members of a population
have the favorable trait, it is called an
adaptation.
• Camouflage is an ability that enables a
species to survive. Through Natural
Selection, nature will “pick” the species
that will survive. This means that predators
will consume prey that is easier to see and
the better adapted organism will live.
Draw this picture and
then label which species
is more likely to survive in
each environment.
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Light-colored moth
Dark moth
While on the Galapagos islands
observing finches, Darwin correctly
concluded that the different beaks were
adaptations to different diets(foods)
available among the islands, thus
forming the concept Natural Selection.
Birds have further adapted to have different
beaks that enable them to eat different
foods. This decreases competition between
species and increases survival due to the
increased food supply for each species.
Natural selection comes down to
two facts and one conclusion:
Fact (1):
Organisms vary and
these variations
(differences) are
inherited by their
offspring.
Fact (2):
Organisms produce more offspring than can possibly
survive in nature. As resources become scarce,
individuals must compete with each other to survive.
Most organisms will not make it to adulthood, and
therefore very few will breed and pass on their genes.
Thousands of frog eggs are laid in clumps in
a fresh water pond. Each clump is laid by
one female. Few will survive to adulthood.
Apple trees produce far more seeds
than could possibly survive to
become full grown trees.
Conclusion:
Those offspring that do survive are best adapted
to their environment and will pass their genes on
to their offspring.
The result is, over time, populations of organisms
become better adapted to their environment by
this process of natural selection.
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For example, this
species of insect is
well adapted (carries
the right genes) to
blend into its
environment.
Do you see the walking stick insect?
It received those genes from its parents, whose genes
were successful enough to allow them to survive
long enough to breed.
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Natural Selection (in summary)
1. Organisms vary and these variations (genes)
are inherited by their offspring.
2. Organisms produce more offspring than can
possibly survive in nature.
3. Those offspring that do survive are best
adapted to their environment and will pass
their genes on to their offspring.
The result is, over time, populations of organisms
become better adapted to their environment
by this process of natural selection.
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Evolution is a slow process.
It is important to understand individual
organisms do not change (adapt) over time.
In general, individuals are either well adapted
(have the right genes) or die before passing
on their genes.
Only populations of organisms evolve.
Due to the movement of continents and
global climate change, environments are
constantly changing which is putting
constant pressure on populations to
evolve.
Assignment
Create a double bubble to
compare and contrast
Natural Selection and
Selective Breeding.
Include as many details as you can. Use your notes for help.