Transcript Physiological Adaptation - University of California, Irvine

Physiological Adaptation
Life in the Lab
Physical Variables

Temperature

Drosophila
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The knock-down time
increased fourfold after 18
generations
Also saw increases in flight
time
There was a shift in the niche
E. coli
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It is possible to adapt E.coli to
specific temperatures and
have them out compete their
ancestor
At almost all temperatures,
specializing in one
temperature did not narrow
the range of temperatures at
which the bacteria could live
Physical Variables

Osmotic Stress

Marine fish

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Originally hypoosmotic relative to
environment and have
chloride cells in their
gills that excrete Na+
and ClGuppies (a fresh
water fish) have been
evolved in high saline
environments

Show an increase in
the number of
chloride cells
Physical Variables

Water
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
Used to define where life can exist
Drosophila
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Can be rapidly adapted to survive in dry environments
Surviving lines tend to have increased body mass,
carbohydrate levels and water contents
Females are more resistant than males
Resource Variable

Food – Starvation Stress
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Drosophila
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When selection took place
with adults they increased
resistance after about 20
generations
When selection took place
with larva there it took
longer to obtain the same
resistance
Adaptations included
increased fat storage and
lowered metabolism
Flies will die of desiccation
before they die of
starvation
Resource Variables

Food

E. Coli

When grown in low nutrient
media they evolved to deal
with the starvation mode
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Some evidence shows
they developed into
cannibals eating their
competitors
Some have evolved the
ability to come out of the
dormant mode quicker
beating those that are
slower to the food