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.

These raw data accompany the article Conley and Lattanzio (2022, Functional Ecology), entitled 'Active regulation of ultraviolet light exposure overrides thermal preference behavior in eastern fence lizards'.  All data were collected on wild eastern fence lizards (Sceloporus undulatus) and done either at our field site or within a university research lab. There are seven (7) total tabs in the EXCEL file. Hereafter we list variables in each tab in the order of appearance from left to right. The first tab (field_and_histogram_data) includes data from the field and data for the histograms shown in Figs. 1 and 2: individual id (capture number), sex (male or female), field body temperature (celsius), field UV exposure (UV index [UVI]), pooled UV set-point minimum and maximum for S. undulatus in our dataset (both in UVI), UV exposure minimum and maximum for S. undulatus estimated in a prior study by Ferguson et al. (2010, Zoo Biology) (in UVI), pooled thermal set-point minimum and maximum for S. undulatus in our dataset (both in Celsius). The second tab (UVdata_Treatments2_3) includes UV data from treatments 2 and 3 in our study: individual id (capture number), sex (male or female), treatment (uv = treatment 2, temp_uv = treatment 3), mean UV preference (in UVI), and UV set-point range (in UVI) values. The third tab (Tempdata_Treatments1_3) includes temperature data from treatments 1 and 3 in our study: individual id (capture number), sex (male or female), treatment (temp = treatment 1, temp_uv = treatment 3), mean thermal preference (in Celsius), and thermal set-point range (in Celsius) values. The fourth tab (SA1 - Body Condition Analysis) includes data used to analyze variation in body condition of S. undulatus in our dataset over time in Supplementary Appendix 1 in our Supporting Information: individual id (capture number), sex (male or female), snout-vent length (SVL, in mm), and weekly S. undulatus mass measurements, starting on the day of capture (=mass1) (all in g). The fifth tab (SA4 - Complementary Analyses) includes data used to analyze difference values in preference and set-point data between treatments including in Supplementary Appendix 4 in our Supporting Information: individual id (capture number), sex (male or female), difference in mean thermal preference (in Celsius), difference in thermal set-point range (in Celsius), difference in mean UV preference (in UVI), and difference in UV set-point range (in UVI). Raw difference values were calculated as a lizard's value in treatment 3 minus their respective value in treatment 1 (for temperature data) or 2 (for UV data). The sixth tab (SF3 - Sensor Calibration Curve) includes data used to calibrate the analog Adafruit UV sensor to the standard sensors produced by Solarmeter 6.5r UV meter, included in Supplementary Figure 3 in our Supporting Information: Solarmeter UVI reading (in UVI), Adafruit UV sensor output (in mV), slope estimate (slope of best-fit linear trendline set to zero intercept), estimated UVI (conversion of Adafruit UV sensor mV into UVI using the slope estimate [=mV * slope estimate]), the raw difference between estimated and actual UVI (in UVI), and the absolute value of the difference between estimated and actual UVI (in UVI). Differences were calculated as Solarmeter UVI reading minus estimated UVI. The seventh tab (Notes) includes two brief notes to clarify to the reader that data used to produce Supplementary Figure 4 and Supplementary Figure 5 in our Supporting Information are the raw data included in the third and second tabs, respectively.

The file is XLSX format, which is typically opened using Microsoft EXCEL. However, these files can also easily be opened using Google Sheets, LibreOffice Calc, or even directly in the statistical software R/RStudio. To analyze the data we recommend using R (or R as implemented via an RStudio interface), as we reference specific packages throughout the data analysis section of Materials and methods, and in our Supporting Information, that we used in this study. All packages are for the R software environment, and free to use/access.