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Evolution
Charles Darwin
• The modern theory of evolution is the
fundamental concept in biology
• Evolution changes populations over time
• Charles Darwin (1809-1882)- was an
English scientist that formed his ideas
about evolution around the information
found in the fossil record
Charles Darwin
• It took Darwin years to develop his theory
of evolution
• He began at age 22 when he took a job as
a naturalist on the English ship HMS
Beagle, which sailed around the world on
a five-year scientific journey
Charles Darwin
• Darwin studied and collected biological
and fossil specimens at every port along
the route
• This made Darwin curious about possible
relationships among species
• Darwin visited the Galapagos Islands,
group of small islands near the equator
Charles Darwin
• Darwin collected specimen on those
islands that could not be found anywhere
else
• From Darwin observations he considered
the possibility that species can change
over time
Charles Darwin
• Upon the return to England, Darwin began
to breed pigeons to try and support his
theory
• Breeding organisms with specific traits in
order to produce offspring with identical
traits is called artificial selection
Natural Selection
• Darwin hypothesized that there was a
force in nature that worked like artificial
selection
• Natural Selection is a mechanism for
change in population
• It occurs when organisms with favorable
variations survive, reproduce, and pass
their variations to the next generation
Adaptations: Evidence for
Evolution
• An adaptation is a variation that aids an
organism’s chances of survival in its
environment. Ex. Thorns on a flower
• According to Darwin’s theory, adaptations
in species develop over many generation
Structural Adaptation
• Mimicry- a structural adaptation that
enables one species to resemble another
species. Ex. Certain flies will resemble
wasps to avoid being eaten
• Camouflage- an adaptation that enables
species to blend with their surroundings.
ex. Stick bugs
Physiological Adaptation
• Physiological adaptations are changes in
an organism’s metabolic processes. Ex.
Insects that are exposed to years of
pesticides, many species become
resistant to these chemicals
Anatomy
• Homologous structures- structural features
with a common evolutionary origin, can be
similar in arrangement, in function, or in
both
• Ex. The forearm of crocodiles, birds,
whales, and humans
Anatomy
• Analogous structures- body parts of
organisms that do not have a common
evolutionary origin but are similar in
function
• Ex. Butterfly wings versus bird wings
Anatomy
• Vestigial structure- a body structure in a
present-day organism that no longer
serves it original purpose, but was
probably useful to an ancestor
• Ex. Baleen whale pelvic bones
Embryology
• An embryo is the earliest stage of growth
and development of both plants and
animals
• The embryos of a fish, a reptile, a bird,
and a mammal are all very similar
• This helps support evolutionary lines
Biochemistry
• Nearly all organisms share DNA, ATP, and
many enzymes among their biochemical
molecules
• Scientist use DNA and RNA nucleotide
sequences to construct an evolutionary
diagram