Download Evolution - High School Science Help

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Evolution
Thing 1: What is evolution?
• Evolution is the changes in genotypes and
phenotypes that occur over time in a
population.
• Natural selection—the different abilities
of organisms to survive and reproduce—
is a major force of evolution.
Thing 2: The more closely related
two organisms are, the more
features they share
•
•
•
•
•
Two cardinals: Most alike
A cardinal and a robin: Less alike
A bird and a lizard: Less alike
A bird and a tree: Less alike
A bird and a bacterium: Least alike
Cardinal
Robin
Birds
Animals
Lizard
Eukaryotes
Tree
Alive
This works when comparing their genes, too!
Bacterium
Homologous structures show common ancestry!
Thing 3: Fossils provide
information about life from the past
• Usually, we can learn about the structure
of the organism
• Sometimes, we can learn about its lifestyle
• Sometimes, we can learn about its
environment
Thing 4: Radioactivity is used to
estimate the age of a fossil
• Radioactive carbon in some fossils can be
measured to determine their age (up to
70,000 years). This is called carbon dating
or absolute dating.
• For older fossils, the age of igneous rock
layers near them can be determined by
measuring other kinds of radioactivity.
This is called relative dating.
Thing 5: Adaptations match form
and function
• Just like the beaks of Darwin’s finches, the
shape of other organisms relates to the
organism’s environment or activities.
• Adaptive radiation describes how one
species can evolve into several related
species, each with its own specialization.
Darwin’s finches
Thing 6: Phylogenetic trees show
how life changes over time
Thing 7: All life on Earth evolved
from a common ancestor
• Because all living things have genes and
structures in common (ribosomes,
phospholipid bilayers, the genetic code,
etc.), there was some common ancestor
from which all life evolved.
Thing 8: Punctuated equilibrium is
one theory about the rate of
evolution
• From the fossil record, it appears that many
species remained relatively unchanged for
long periods of time followed by relatively
short periods of rapid change. That is the
theory of punctuated equilibrium.
Thing 9: A phenotype that is best fit
for one environment might be unfit
for another environment
• Fitness isn’t absolute. It’s an advantage for
a polar bear to be white, but not for a
grizzly bear.
Thing 10: Lamarck had an incorrect
theory about evolution.
• Lamarck said that offspring inherit
characteristics that their parents acquire
during their lifetime.
• By that logic, we would all be born
knowing how to drive.