Data from: Starvation effects on nitrogen and carbon stable isotopes of animals: an insight from meta-analysis of fasting experiments

Nitrogen and carbon stable isotopic compositions (δ15N and δ13C) of
consumers have been used for physiological and food web studies. Previous
studies have shown δ15N and δ13C values are affected by several biological
and environmental factors during starvation, but the generality of the
effect of starvation on δ15N and δ13C values has not yet been tested.
Here, we performed a meta-analysis to evaluate the effects of starvation
on δ15N and δ13C values of consumers, and the underlying factors that may
explain the observed variation. The δ15N and δ13C values were calculated
as the differences between the final δ15N and δ13C values of consumers
(post-starvation) and the pre-starvation values on each experiment. Our
meta-analysis showed a large variation in the δ15N and δ13C values of
consumers (δ15N range: –0.82 to 4.30‰; mean: 0.47‰ and δ13C range: –1.92
to 2.62‰; mean: 0.01‰). The δ15N values of most consumers increased along
the length of the starvation period and were influenced by nitrogen
excretion and thermoregulation types, probably because differences in
nitrogen metabolism and thermoregulation affect nitrogen processing and
excretion rates. None of our predictor variables accounted for the
variation in δ13C values, which showed both increases and decreases due to
fasting. Our findings suggest that starvation results in changes in
consumer δ15N values which are mainly explained by the length of the
fasting period and by nitrogen and energy metabolism, but the underlying
mechanisms of the starvation effects on δ13C values seem to be more
complex than previously thought.