Data from: Modeling the effect of environmental temperatures, microhabitat, and behavioral thermoregulation on predicted activity patterns in a desert lizard across its thermally diverse distribution

Aim Temperature plays an important role in determining distributions of ectothermic species, yet many ectotherms have wide distributions across diverse environmental conditions. Our goal was to model regional differences in annual and seasonal activity patterns among populations of Phrynosoma platyrhinos across its climatically diverse distribution. We hypothesize that microhabitat availability and behavioral thermoregulation will not mitigate large-scale climatic differences across the species' distribution, resulting in alteration of activity patterns of populations. Location Western deserts of North America. Taxon Desert Horned Lizard (Phrynosoma platyrhinos) Methods We used biophysical models to 1) model microhabitat conditions at 31 localities across the species' range, 2) model body temperature profiles of a theoretical lizard using microhabitat conditions, physiological and thermal parameters, and the ability of lizards to thermoregulate behaviorally, and 3) predict year-round activity patterns of P. platyrhinos across its range, quantified as the percentage of time permissible for basking or foraging. Results The models identified that different populations of P. platyrhinos experience differences in predicted activity patterns, both daily and seasonally, with up to 67% more time suitable for foraging in the southern than northern deserts. Southern populations have more potential for year-round activity, but predicted activity is reduced during hot summer months. The northern populations have less time for activity overall because of low temperatures in the spring and fall. However, summer predicted activity is greater than in the southern regions. Main conclusions We detected pronounced regional differences in the times available to P. platyrhinos for activity. We conclude that behavior and microclimate conditions are not able to fully mitigate the effects of large-scale thermal variation, and that lizards compensate for climatic variation by shifting their daily and seasonal predicted activity patterns. These differences can be tied to inter-population variation in life history traits.

【研究目标】体温是决定变温动物（ectothermic species）分布格局的核心调控因子之一，但诸多变温类群仍可在多样的环境梯度中拥有广阔的分布范围。本研究旨在针对气候异质性分布的沙漠角蜥（Phrynosoma platyrhinos）不同种群，构建其年度与季节活动格局的区域差异模型。我们提出如下假设：微生境可获得性与行为性体温调控（behavioral thermoregulation）无法抵消该物种分布范围内的大尺度气候差异，进而导致不同种群的活动格局发生改变。
**研究区域**：北美洲西部荒漠。
**研究类群**：沙漠角蜥（Phrynosoma platyrhinos）。
**研究方法**：本研究采用生物物理模型（biophysical models）开展如下3项工作：1）对该物种分布范围内31个采样点的微生境条件进行建模；2）基于微生境条件、生理与热参数，以及蜥蜴的行为体温调控能力，构建理论个体的体温变化曲线；3）预测沙漠角蜥在全分布区的全年活动格局，以适宜晒太阳或觅食的时间占比作为量化指标。
**研究结果**：模型结果显示，沙漠角蜥不同种群的日活动与季节活动格局均存在显著区域差异：南部荒漠种群适宜觅食的时间较北部荒漠种群最多高出67%。南部种群全年具备更高的活动潜力，但在炎热夏季其预测活动时长会有所降低；北部种群因春秋季气温偏低，整体活动时长偏少，但夏季的预测活动时长却高于南部种群。
**主要结论**：本研究发现沙漠角蜥的可活动时长存在显著的区域异质性。结果表明，行为调控与微生境条件无法完全抵消大尺度热环境差异带来的影响，蜥蜴通过调整日活动与季节活动格局来应对气候异质性；这类区域差异与种群间的生活史性状变异密切相关。