Consumer nutrient stoichiometry : patterns, homeostasis, and links with fitness.
2010-10
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Consumer nutrient stoichiometry : patterns, homeostasis, and links with fitness.
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2010-10
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Thesis or Dissertation
Abstract
The
linkages
between
food
webs
and
nutrient
cycles
are
heterogeneous
and
often
influenced
by
human
activities.
Ecological
stoichiometry
provides
one
framework
for
understanding
and
predicting
these
linkages.
Yet,
as
it
has
been
extended
underlying
assumptions
are
often
not
evaluated.
This
dissertation
shows
that
examination
of
implicit
and
explicit
assumptions
reveals
unknown
mechanisms,
interactions,
and
linkages.
For
instance,
theory
assumes
that
invertebrate
stoichiometry
does
not
vary
with
diet
stoichiometry
(i.e.,
strict
homeostasis),
even
though
many
invertebrates
are
not
strictly
homeostatic.
Chapters
one
and
two
examine
the
role
of
stoichiometric
homeostasis
in
shaping
the
fitness
of
Daphnia
species.
Chapter
one
shows
that
the
long-‐term
phosphorus
(P)
use
efficiency
of
stoichiometrically
flexible
Daphnia
species
is
higher
in
habitats
with
temporally
variable
diets,
resulting
in
higher
fitness
relative
to
strictly
homeostatic
species.
Chapter
two
shows
that
the
P
cost
of
a
unit
of
growth
increased
with
growth
rate
and
structures
tradeoffs
among
growth
rate,
sensitivity
to
P
limitation,
and
stoichiometric
flexibility.
Stoichiometric
theory
can
be
extended
to
novel
ecosystems,
such
as
streams,
to
predict
the
role
of
consumers
in
food
web
and
nutrient
cycles.
To
do To
do
this,
the
balance
between
consumer
and
diet
stoichiometries
is
a
logical
starting
point.
Chapter
three
examines
intra-‐specific
variation
in
consumer-‐resource
stoichiometries
at
a
suite
of
sites
within
a
river
network.
In
contrast
to
previous
work,
this
chapter
describes
wide
intra-‐
specific
variation
in
consumer
stoichiometry,
similar
in
magnitude
to
the
variation
among
invertebrate
taxa.
Intra-‐specific
variation
in
nitrogen
and
phosphorus
content
was
related
to
both
ontogeny
and
diet.
These
results
suggest
that
the
role
of
a
species
in
stream
nutrient
cycles
could
vary
spatially
with
diet
and
temporally
through
ontogeny.Chapter
four
examines
the
influence
of
diet
stoichiometry
on
nutrient
release
ratios
of
four
stream
detritivores.
Predictions
of
nutrient
release
ratios
from
bulk
diet
stoichiometries
were
misleading
for
these
detritivores,
which
selectively
consumed
a nutrient
rich
portion
of
the
bulk
diet.
Selective
feeding
greatly
reduced
stoichiometric
mismatches
between
these
consumers
and
their
diets.
Taken
together,
this
dissertation
demonstrates
that
examination
of
stoichiometric
assumptions
improves
our
understanding
of
consumer-‐resource
dynamics,
competition,
and
the
role
of
consumers in
nutrient
cycles.
Description
University of Minnesota Ph.D. dissertation. October 2010. Major: Ecology, Evolution and Behavior. Advisors: Drs.
Jacques
C.
Finlay
and
Robert
W.
Sterner, 1 computer file (PDF); ix, 165 pages
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Hood II, James Michael. (2010). Consumer nutrient stoichiometry : patterns, homeostasis, and links with fitness.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/99973.
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