Download Science 9 Topic 6 The Best Selection

Biological Diversity
Topic 6
The Best Selection
The Best Selection
Do you have a
cat or a dog at
home?
Do you own a
pet rabbit?
– These animals are
considered
Domestic.
The Best Selection
Domestic Animal:
– An animal that is no longer wild, but has
been bred or tamed by humans to perform
various functions.
– Ex. Cows for milk and meat, chickens for
eggs and meat, horses and donkey for
labour etc.
The Best Selection
Artificial Selection / Selective
Breeding:
– Technique in which individual plants
or animals with desirable traits are
bred together to develop plants or
animals with specific traits
– Artificial selection has been used by
people for thousands of years to
produce domestic plants and animals
with particular characteristics
The Best Selection
Ex. Corn used to be
purple with only 12
kernels per cob
Ex. Carrots used to be
smaller and purple and
were bred to be large
and orange by the
Dutch
Ex. Horses used to be
too small to carry us
Artificial Selection in
Agriculture
Our ancient hunter-gatherer ancestors
began planting wheat and barley seeds as
a reliable food source around 10000
years ago in the fertile crescent (modern
day Iraq)
Artificial Selection in
Agriculture
Though wheat was
domesticated during
prehistoric times, both
wheat and rice now
make up 40% of the
human population’s
energy supply
Artificial Selection in
Agriculture
Selective Breeding:
– Also known as Artificial Selection
– Selective Breeding has allowed
many cultures around the world
to create new and more useful
food crops
Artificial Selection in
Agriculture
In Canada Wheat crops such as “Western
Red Spring Wheat” was created through
selective breeding because its flour is
good for making pan bread
Artificial Selection in
Agriculture
Other forms of wheat were created for
other functions such as “Canadian
Western Amber Durum” wheat whose
flour is good for making pasta
Artificial Selection in
Agriculture
Researchers are also concerned with
which wheat will grow in which climate
and selectively breed wheat to grow in
these areas
Artificial Selection in
Agriculture
Other selective breeding programs
create wheat varieties that are resistant
to insects and disease etc.
Dr. Ohm - Wheat breeding
Rust Resistant Durum Wheat
Accounting for Biological
Diversity
Charles Darwin is
one of the most
famous biologists of
all time due to his
theory of Natural
Selection
Accounting for Biological
Diversity
Darwin came up with his idea after
taking a voyage on the H.M.S. Beagle
to the Galapagos islands off the coast
of South America in 1831
Accounting for Biological
Diversity
While in the Galapagos,
Darwin recognized that
there were a variety of
Finches (a small bird) on
the islands, each with
different adaptations that
allowed them to feed on
different food sources
avoiding competition
with each other
Accounting for Biological
Diversity
He realized that these
adaptations due to competition
were caused by natural
pressures put onto the Finches
by their environment
A look at the finches of the
Galapagos islands
Accounting for Biological
Diversity
When the Beagle
returned to England,
Darwin published his
famous book called the
“Origin of Species by
Means of Natural
Selection” in 1859
changing the way that
Biologists viewed the
world forever
The Theory of Natural
Selection
Natural Selection:
– A naturally occurring
process in which only
those organisms with the
best traits for survival in
an environment survive to
reproduce.
– Over time this process
results in changes in the
genetic characteristics of a
species.
The Theory of Natural
Selection
The theory of natural selection can be
summed up in four statements:
1.
2.
3.
4.
–
All organisms produce more offspring than can
possibly survive
There is incredible variation within each species
Some of these variations increase the chances of an
organism surviving to reproduce
Over time, variation that are passed on lead to
changes in the genetic characteristics of a species.
Evolution Primer #4: How Does Evolution Really
Work?
The Theory of Natural
Selection
Ex. The Giraffe
• The ancient ancestors of the
Giraffe had short necks
• As food became scarce,
those Giraffe ancestors with
slightly longer necks (a
natural variation) were able
to eat food from taller trees
• These Giraffe ancestors were
able to survive better and
mate more often
The Theory of Natural
Selection
Ex. The Giraffe cont’d
• Their offspring had slightly longer necks and due
to variation some of the offspring had naturally
longer necks than their siblings
• These Giraffe ancestors were able to survive
better and mate more often passing on their
genes to the next generation
• After millions of years and countless generations
the necks of Giraffes became as long as they are
today
The Theory of Natural
Selection
Ex. The Giraffe cont’d
• **Note: As the Giraffe evolved to have a longer
neck, the trees that they fed on also evolved to be
taller so that they weren’t eaten and killed by
Giraffes. This is called co-evolution
The Theory of Natural
Selection
Ex. The Peppered Moth
–
There are two varieties
of the peppered moth in
England, a light colour
and a dark colour
–
The light coloured
peppered moth was the
most common as it
easily camouflaged with
the trees it sat on and
therefore was not eaten
The Theory of Natural
Selection
Ex. The Peppered Moth cont’d
–
–
–
–
During the industrial revolution trees in England began to
turn black with soot
The less common black peppered moth was able to
camouflage better and thus survived better and was able
to mate more, passing on its genes to the next generation
The black peppered moth then became more common
than the white peppered moth
Evolution of the Peppered Moth