Data from: Warm nocturnal temperatures act as an ecological trap for a diurnal lizard

The effects of increasing nighttime temperatures remain underexplored,
despite that nocturnal temperatures are rising at a faster rate than
diurnal temperatures and are expected to negatively impact
fitness-relevant physiological processes such as recovery and growth. An
initial response to warming environments is behavioural thermoregulation,
which enables ectotherms to rapidly adjust to changing environmental
conditions. The behavioural responses of ectotherms to warmer diurnal
temperatures have been well-documented; however, little is known about
nocturnal thermoregulation. In this study, we experimentally assessed the
impact of elevated nocturnal temperatures on retreat site selection and
thermoregulation strategies in the diurnal common wall lizard (Podarcis
muralis). Using semi-natural mesocosms, we exposed adult male lizards to
two distinct nocturnal temperature treatments (control vs. a ~4°C
increase) and recorded their body temperatures continuously over two weeks
with wearable temperature loggers. Lizards in the warmer treatment
selected warmer nocturnal retreats and exhibited significant
among-individual variation in nocturnal site choice. Furthermore, there
was no shift in selected diurnal temperatures to compensate for nocturnal
exposure. Lizards in the warm treatment suffered reduced body conditions
by the end of the experiment, suggesting that the behavioral response to
warmer nocturnal temperatures does not mitigate the physiological costs.
This study confirms the potential for nocturnal warming to create an
ecological trap for diurnal species: lizards will select warmer
temperatures when available at night, despite these behaviors being
maladaptive. Our findings underscore the need for further research on the
long-term impacts of nocturnal warming on fitness and the adaptive limits
of plastic responses in diurnal ectotherms.