A simulated heat wave has diverse effects on immune function and oxidative physiology in the corn snake (Pantherophis guttatus)
Stahlschmidt, Z. R.; French, S. S.; Ahn, A.; Webb, A.; Butler, Michael W.
Animals will continue to encounter increasingly warm environments,
including more frequent and intense heat waves.
Yet the physiological consequences of heat waves remain equivocal,
potentially because of variation in adaptive plasticity (reversible
acclimation) and/or aspects of experimental design. Thus,
we measured a suite of physiological variables in the corn snake
(Pantherophis guttatus) after exposure to field-parameterized,
fluctuating temperature regimes (moderate temperature and heat
wave treatments) to address two hypotheses: (1) a heat wave
causes physiological stress, and (2) thermal performance of
immune function exhibits adaptive plasticity in response to a
heat wave. We found little support for our first hypothesis
because a simulated heat wave had a negative effect on body
mass, but it also reduced oxidative damage and did not affect
peak performance of three immune metrics. Likewise, we
found only partial support for our second hypothesis. After
exposure to a simulated heat wave, P. guttatus exhibited greater
performance breadth and reduced temperature specialization
(the standardized difference between peak performance and
performance breadth) for only one of three immune metrics
and did so in a sex-dependent manner. Further, a simulated
heat wave did not elicit greater performance of any immune
metric at higher temperatures. Yet a heat wave likely reduced
innate immune function in P. guttatus because each metric of
innate immune performance in this species (as in most vertebrates)
was lower at elevated temperatures. Together with previous
research, our study indicates that a heat wave may have
complex, modest, and even positive physiological effects in some
taxa.
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