Transcript The Man with the Plan

The Man with the Plan
Voyage of the Beagle
• Charles Darwin was born on Feb. 12th, 1809.
• Fortunate to be on the crew for the H.M.S.
Beagle in 1831.
• Set sail around the world and recorded his
observations of plant and animal life.
The Questions
• Is there some type of process that leads to
such a variety of ways of living and
reproducing?
• Why have so many species disappeared?
• Why are so many living species suited so well
for their environment?
How is a polar bear adapted to its extremely cold climate?
white greasy fur repels water and acts as camouflage
thick fur and body fat
insulate from the cold
large, wide feet spread the
body’s weight and act as
good paddles and snow
shoes
Other adaptations that polar bears have evolved to cope
with conditions in the harsh polar environment include:
small ears and small body surface area to
volume ratio reduces heat loss
eyes have brown irises to reduce the
glare from the Sun’s reflection
black skin is a good absorber of
heat
The Galapagos Islands
• Characteristics of certain animals varied based
on what island they inhabited.
• These characteristics were established as
adaptations.
– Inherited characteristic that increase an
organism’s chance of survival and reproduction.
Galápagos finches
In the Galápagos, Darwin noticed that different islands had
different types of finches, with different types of beak.
 Some finches had strong and claw-like
beaks, suitable for crushing seeds.
 Other finches had thin and delicate beaks,
suitable for picking insects from holes in
the ground.
Darwin thought all the finches could have evolved from one
type of finch that came from the mainland.
Natural variation meant that some finches had slightly
different beaks. These finches would have been able to eat
different types of food and avoid competition. They would
therefore have survived and passed on their genes.
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Artificial Selection
Artificial Selection
Artificial Selection
Inherited Variation
• Darwin observed that variation exists among
organisms.
– Breeders used heritable variation for better crops and
livestock.
• Artificial Selection
– Nature provides variation, humans select the variation
they find useful.
• These variations can be passed from parent to
offspring.
• At the time of his publication Darwin had no
understanding of genetics.
The Big Idea
• Does this idea apply to nature?
• An idea of natural selection as the process by
which evolution occurs?
• Struggle for existence.
– Intra and interspecific competition.
– Those best suited for their environment can catch
prey and avoid being caught. Cheetah video?
Natural Selection
• Process where organisms with certain
inherited characteristics (adaptations) are
more likely to survive and reproduce than are
organisms with other characteristics.
– This process is not guided by increased
complexity.
– Organisms can not “want” a specific adaptation.
Fierce Competition
Survival of the Fittest
• Biological Fitness
– Ability of an individual to survive and reproduce in
its environment.
– How many offspring you have is a measure of your
fitness.
Evolution
• Describe our class’s current understanding of
evolutionary theory.
Natural Selection
MECHANISM FOR EVOLUTION
• Organisms differ and some of this variation is
heritable.
• Some of these variances result in great
reproductive potential (increased fitness).
• Resources are limiting.
• Some organisms survive and reproduce to
pass their heritable traits to their offspring.
• Darwin proposed that over long periods,
natural selection produces organisms that
have different structures, establish
different niches or occupy different
habitats.
• He called this idea DESCENT WITH
MODIFICATION
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Natural Selection Game
• http://phet.colorado.edu/en/simulation/natur
al-selection