Transcript Crash Course in Evolution!

Crash Course in Evolution!
Biology Objectives for EOC Exam
A. Spontaneous Generation (& Redi,
Needham, Spallanzani, and Pasteur)
No, not really!!!
• Spontaneous Generation – idea that some
living things arose spontaneously from nonliving matter
– Ex: in the 17th century, one recipe for “producing”
mice involved putting sweaty underwear and
husks of wheat into a jar and waiting 21 days.
– AND: maggots from rotting meat, fish from mud,
beetles from cow dung
• Francesco Redi (1668)– experimented with meat to
see if maggots were spontaneously created, OR the
result of flies laying their eggs in it
– Conclusion: He suspected it was the flies, but said that
SG still occurred in some cases!
• John Needham (1745)– experimented to see if
microorganisms grew after chicken broth was
boiled (so that previously existing
microorganisms were killed). They did!
– Conclusion: Spontaneous generation DOES occur!
• Lazzaro Spallanzani – not convinced by Needham’s
experiment, said that microorganisms could have
come from the air, modified Needham’s experiment
to test this.
– Conclusion: Spontaneous generation did not occur! (But
others said that he only proved it did not occur without
air present.)
• Louis Pasteur (1859) – combined Redi &
Spallanzani’s experiments. Working with meat
broth in a flask, he allowed air to get in but shaped
the flask so that microorganisms “settled out” of
the air before getting to the broth.
– Conclusion: Spontaneous generation does not occur!
B. Evolution is…
• Descent with modification
– Genetic change in a species over a period of time
• Some scientists say that life on earth has evolved to
be very diverse, but shared common ancestors.
C. Chemical & organic evolution
• Chemical evolution chemical changes on the
primitive Earth that allowed
life to exist.
• Organic evolution – the slow,
gradual change in life forms
throughout history (from
simple single-celled
organisms to more complex
multi-celled organisms)
Heterotrophs vs. Autotrophs
• Heterotrophs: obtain energy by
feeding on others.
• Autotrophs: make their own food
via photosynthesis
• Heterotroph hypothesis 
suggests that heterotrophs were
the first organisms on Earth and
that autotrophs evolved from
them. Does not try to explain the
origin of the first heterotrophs
though!
D. Darwin, survival of the fittest, and
natural selection
• British naturalist, loved/studied
nature
• Embarked on a 5 year journey
around the world on the HMS
Beagle
• Studies of specimens & diverse
life around the world led him to
develop this theory of
evolution and views on natural
selection
“Survival of the fittest”  Darwin’s idea that
organisms best-suited for their environment will
survive, reproduce, and pass on their traits.
http://www.youtube.com/watch?v=AMtT5_AQmLg
Natural Selection
http://evolution.berkeley.edu/evolibrary/article/
evo_25
• Must begin with genetic variation!
• Ex: Peppered moth
E. Influences on Darwin’s ideas…
• Malthus – “overproduction” in nature, more
offspring are produced than can survive (became
part of Darwin’s idea of natural selection)
• Wallace – developed a theory of
evolution similar to Darwin’s, acted as a
collaborator, shared research with him
• Lyell – geologist, Darwin used his book
about about geology/rock formations to
help him understand more about fossils
he gathered
• Lamarck – believed that organisms evolved toward
perfection, species didn’t become extinct just
changed into different species, and that “acquired”
characteristics could be passed on (Ex: giraffe’s
necks got longer when they stretched for food)
• The Journey (HMS Beagle) – 5 years of
studying, gathering information about life
forms from around the world, Darwin was
impressed with the diversity of life!
F. Lamarck vs. Darwin
G. Behaviors that have evolved
through natural selection
– Courtship rituals http://newswatch.nationalgeographic.com/
2013/02/14/wild-romance-weird-animalcourtship-and-mating-rituals/
– Migration – birds flying south for winter,
etc.
– Defense mechanisms – skunks’ odor,
mimicry, porcupine quills,
http://webecoist.momtastic.com/2008/11/04/9of-the-most-bizarre-animal-defense-mechanisms/
H. Conditions required to be a species
• Species  group of related organisms that can
interbreed in nature and produce fertile offspring.
(reproductively separated from other species)
• Speciation (creating of new species) can occur by:
– Reproductive isolation: members of two groups are
unable to reproduce (different courtship rituals,
different breeding seasons, sex organs aren’t compatible
etc.)
– Geographical isolation: members of a species become
separated by river, earthquake, etc.
I. Types of selection
J. Natural selection and evolutionary
consequences explain the fossil record
• Fossils will show similar adaptations because
species had to adapt to a specific environment
in order to survive.
• Fossil record will show that species that have
gone extinct lack the adaptations needed to
survive in their environment.
L. Evidence from geology, biochemistry,
embryology, comparative anatomy, &
comparative physiology
• Geology – fossil record, rock layers
• Biochemistry – similarities in DNA, molecules
making up organisms
• Embryology – similarities in the embryonic
development of various species
• Comparative anatomy & physiology –
similarities in body structure and function
N. Catastrophism, gradualism,
punctuated equilibrium
• Catastrophism – idea that Earth’s crust has
been scarred by catastrophic events
• Gradualism – idea that evolution occurs at a
slow, steady pace and is constant
• Punctuated Equilibrium – idea that evolution
occurs in spurts, not constantly