Transcript Natural Selection vs. Selective Breeding

Natural Selection vs. Selective
Breeding
Shopping PPT
7th Grade Science
Selective Breeding
• SELECTIVE BREEDING is the process of
choosing parent organisms for the
characteristics that we want in their offspring.
• Who plays a large role in this process? We do,
as HUMANS! ☺
Selective Breeding Examples
• MATING male and female English BULLDOGS that
exhibit characteristics and selling their
OFFSPRING.
• Farmers choosing the TRAIT they want from the
CROP to breed.
• SELECTIVE BREEDING can include ranchers
breeding cows and buffalo to get a certain kind of
meat.
It Gets Lonely in the Desert
• To survive in the desert, plants must adapt to
their environment. This can include:
• Having short roots
• Waxy coats on their leaves
• Some desert plants bloom only at night
because the SPECIES RELIES ON NOCTURNAL
ANIMALS FOR POLLINATION.
Adapt, Adapt, Adapt!
• PLANTS and ANIMALS are two types of
organisms that adapt to their environments.
• Adaptations helps species SURVIVE and
REPRODUCE in their ENVIRONMENT.
• Adaptations often evolve from a MUTATION
and gave the species an ADVANTAGE.
Adapt, Adapt, Adapt!
• Adaptations occur OVER TIME and can be
PHYSICAL or BEHAVIORAL.
• Adaptations must be common amongst a
POPULATION. They CANNOT occur in just a single
INDIVIDUAL.
• To avoid predators, an organism might
CAMOUFLAGE COLORING, LIVE IN GROUPS, and
have SENSITIVE HEARING.
Adapt, Adapt, Adapt!
• If body temperature rises, the adaptive
response would be to SWEAT.
• To survive in cold weather, humans must keep
warm! One human adaptation to survive in
cold weather is to GROW HAIR TO INSULATE
THE HEAD.
Adapt, Adapt, Adapt!
• CAMOUFLAGE is an example of an adaptation.
The SNOWSHOE HARE changes its color from
brown to white to blend into the snow during
winter.
• One adaptation of dandelions is that they are
attached to stems with light, fluffy threads.
This helps them DISPERSE SEEDS VIA THE
WIND.
Let’s Eat!
• What do you like to eat???
• Some animals, like SHARKS have very SHARP teeth
to eat only MEAT.
• Deer are herbivores, so their teeth are more FLAT
to chew leaves or plants.
• Humans are OMNIVORES, so they have both.
Natural Selection—Charles Darwin
• CHARLES DARWIN’S theory of natural
selection stated that individual that tend to
survive have VARIATIONS BEST SUITED FOR
THAT ENVIRONMENT.
• Darwin studied the FINCHES on the
Galapagos Islands. He noticed they had
different BEAKS. They formed so the birds
could EAT DIFFERENT FOODS.
Natural Selection
• NATURAL SELECTION is the process that leads
to the most VARIATIONS.
• The Peppered Moth had a change in
population caused by NATURAL SELECTION.
• Natural selection is NOT the survival of the
STRONGEST and BIGGEST organisms in a
population.
Homeostasis
• HOMEOSTASIS is the process of trying to
maintain an internal stable environment
despite an ever-changing external
environment.
• As humans, our bodies use mostly NEGATIVE
feedback to maintain stability, or
homeostasis.
Homeostasis
• Positive feedback tends to be more RARE. An
example of positive feedback would be
APPLES RIPENING ON A TREE.
• When apples ripen, they give off a gas called
ETHLENE which causes other surrounding
apples to ripen as well.
Homeostasis
Example
Apples Ripening
Positive Feedback
X
Thermostat/AC
Breastfeeding
Negative Feedback
X
X
Oxygen levels in the body
X
Blood sugar levels in the body
X
Shivering
X
Key Terms
Adaptation
A structure, behavior, or other trait in an organism
that helps it survive in its environment
Variation
A property of a population that occurs when
individuals within a population differ in the
characteristics
Natural Selection
Survival and reproduction of the organisms that are
genetically best adapted to the environment
Homeostasis
Selective Breeding
The process by which an organisms’ internal
environment is kept in equilibrium, or stable in
spite of changes in the external environment
The process of choosing parent organisms for the
characteristics that we want in their offspring