Data from: Active regulation of ultraviolet light exposure overrides thermal preference behaviour in eastern fence lizards

1. Over a century of ecophysiological studies on lizards have perpetuated
the assumption that basking and shuttling movements between sun and shade
function solely for temperature regulation. However, these behaviors also
modulate exposure to ultraviolet (UV) wavelengths that are essential for
maintaining physiological homeostasis as well as ensuring proper growth
and development and enhancing long-term fitness. 2. An alternative
hypothesis is that lizards also actively regulate their UV exposure. In
this scenario, UV needs may even override temperature needs (or vice
versa), generating asymmetries in the ability of a lizard to regulate both
conditions equally. We test this hypothesis using field and laboratory
data collected on adult Sceloporus undulatus. 3. We found that S.
undulatus actively regulate UV exposure and prioritize UV over
temperature, favoring body temperatures much higher than preferred values
to sustain preferred UV exposure. In stark contrast, temperature had no
reciprocal impact on UV regulation behavior. Our field data support these
patterns, suggesting that lizards may even seek out hotter environments
despite thermal costs to enhance UV exposure. 4. We conclude that S.
undulatus actively regulate for UV as well as temperature. Unfortunately,
outside of zoos and private hobbyists, appreciation of the importance of
UV for ectotherm survival and reproductive success has been minimal.
Addressing this deficit will therefore be vital to improve our
understanding of the factors shaping the evolution of ectotherm
photoregulation behavior in nature.