Transcript Natural Selection

Natural Selection
Evolution
Descent with modification or Change in a
population over time
Natural Selection
Natural selection is one of
the basic mechanisms of
evolution, along with
mutation, migration, and
genetic drift.
Some factor in the
Environment selects
those individuals that are
best suited to their
environment to survive
and reproduce, thus
changing the population
over time.
Overproduction of Offspring
Organisms tend to
produce more
offspring than can
survive.
Inherited Variation
• Offspring are born with
different traits
(phenotype) because of
different gene
combinations.
• Differences are the
result of : mutations,
crossing over, and/or
independent
assortment.
Competition to survive
• There is a finite
supply of
environmental
resources like…
Food, shelter, mates,
water, avoiding
predation, sunlight,
oxygen, etc.
Adaptation
• Those individuals who are
born with variations that
help them to survive are said
to have an adaptation.
• Variation is random and so
an individual cannot choose
to have an adaptation
• An advantage in one
environment is sometimes a
disadvantage in another.
Reproduction
“Differential Reproductive Success”
Survival of the fittest –
those individuals who
are better suited to
their environment will
survive and reproduce
most successfully.
It is the individual who
leaves behind the most
offspring who “wins”
Result
• Over time traits that
lead to more
offspring accumulate
in the environment
and the population
becomes better
suited to their
environment.
Industrial melanism
Activities
• Read survival of the sneakiest article and answer
the questions
http://evolution.berkeley.edu/evolibrary/article/s
neakermales_01
• Make a cartoon showing overproduction,
variation, finite resources/competition, natural
selection/differential survival and reproduction
• Peppered moth simulation
http://www.biologycorner.com/worksheets/pepper
edmoth.html
http://peppermoths.weebly.com/
Ideas for your cartoon…
Coevolution