Data from: Reduction of baseline corticosterone secretion correlates with climate warming and drying across wild lizard populations

1. Climate change should lead to massive loss of biodiversity in most taxa
but the detailed physiological mechanisms underlying population extinction
remain largely elusive so far. In vertebrates, baseline levels of hormones
such as glucocorticoids (GCs) may be indicators of population state since
their secretion to chronic stress can impair survival and reproduction.
However, the relationship between GC secretion, climate change and
population extinction risk remains unclear. 2. In this study we
investigated whether levels of baseline corticosterone (the main GCs in
reptiles) correlate with environmental conditions and associated
extinction risk across wild populations of the common lizard Zootoca
vivipara. 3. First, we performed a cross-sectional comparison of baseline
corticosterone levels along an altitudinal gradient among 14 populations.
Then, we used a longitudinal study in 8 populations to examine the changes
in corticosterone levels following the exposure to a heat wave period. 4.
Unexpectedly, baseline corticosterone decreased with increasing thermal
conditions at rest in females, and was not correlated with extinction
risk. In addition, baseline corticosterone levels decreased after exposure
to an extreme heat wave period. This seasonal corticosterone decrease was
more pronounced in populations without access to standing water. 5. We
suggest that low basal secretion of corticosterone may entail
down-regulating activity levels and limit exposure to adverse climatic
conditions, especially to reduce water loss. These new insights suggest
that rapid population decline might be preceded by a down-regulation of
the corticosterone secretion.