Transcript Heterotrophic Hypothesis

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Evolution is change over time
Proof of evolution
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Fossils
Comparative anatomy
Embryology
Cytology
Biochemistry
 The sequence of amino acids in the cytochrome c
molecule, an enzyme found in mitochondria, is
identical in humans and chimpanzees
fossils
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Composition: molten body  solid crust
surface (hot)
Atmosphere – probably gases from volcanic
eruptions
◦ Oxygen-poor
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Eventual cooling, formation of oceans  life
on Earth (~3.5 billion yrs ago)
Heterotrophic Hypothesis: organic chemistry
may spontaneously form from inorganic
chemistry
 autotrophs developed after the evolution of
heterotrophs partly because the primitive
environment of the Earth lacked carbon
dioxide
 Miller-Urey Experiment
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First cells: prokaryotic
Prokaryotes
have no
nucleus and
no
membrane
environmentsbound
(like
organelles
◦ Small
◦ Capable of living in extreme
deep sea vents)
◦ Then the appearance of photosynthesizing
prokaryotes (cyanobacteria)
 Production of oxygen  ozone layer  appearance of
eukaryotes
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~1.8 billion years ago
Endosymbiont Theory: eukaryotic cell
ancestors living in association with
prokaryotic cells
Evidence for the endosymbiont theory
◦ mtDNA & cpDNA, and its circular arrangement
◦ Prokaryotic ribosomes
◦ Mitochondria and chloroplast reproduction by
fission
Eukaroytes have a
nucleus and
membrane bound
organelles
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Lamarck- use and disuse
◦ When environments changed, organisms had to
change their behavior to survive.
◦ If they began to use an organ more than they had
in the past, it would increase in its lifetime.
◦ If a giraffe stretched its neck for leaves, for
example, a "nervous fluid" would flow into its neck
and make it longer.
◦ Its offspring would inherit the longer neck, and
continued stretching would make it longer still over
several generations.
◦ Meanwhile organs that organisms stopped using
would shrink.
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Darwin- natural selection
Finches
Peppered moth game
peppered moth simulation
Ant simulation
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Conditions vital to this process are
◦ Overproduction
◦ Finite resources
◦ Genetic variation (mutation and sexual reproduction
including crossing over)
 Adaptive value
◦ Selection by the environment of those better able to
survive and reproduce
 “survival of fittest”
◦ Stabilizing selection: favors
a mean, eliminates extremes
(ex: birth weight)
◦ Directional selection: favors
one extreme (ex: peppered
moth)
◦ Disruptive selection: favors
two extremes, eliminates the
mean (ex: Northern water
snakes color patterns)
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Camouflage: Cuttlefish, Leafy Sea Dragon
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Mimicry: evolving to resemble another
species (drone fly, ash borer)
• Gradualism: selection and variation that happens
more gradually
 Over a short period of time it is hard to notice
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Punctuated equilibrium: change comes in
spurts
◦ There is a period of very little change, and then one
or a few huge changes occur