Infrared camouflage in leaf-sitting frogs: A cautionary tale on adaptive convergence

Many green animals that appear cryptic against green leaves also match leaf reflectance in the near-infrared (NIR). It is unlikely that this NIR background matching contributes to visual camouflage because animals do not see NIR light. Two alternative explanations have been proposed –  infrared camouflage (i.e. matching the temperature of the background) and thermoregulation – but neither hypothesis has been experimentally tested. To test these hypotheses, we developed coatings that manipulate NIR reflectance independently from visible reflectance. We produced agar frog models that mimic the reflectivity of different species of leaf-sitting frogs, which are visibly green but differ greatly in NIR reflectance. We compared heating rates and temperature (surface and core) of high and low NIR reflectance frog models in the laboratory using a solar simulator, and in tropical rainforest – the natural habitat of leaf-sitting frogs. In the laboratory, agar frog models with low NIR ref..., , , # Infrared camouflage in leaf-sitting frogs: A cautionary tale on adaptive convergence **File: 1_LabDataAnalysis.Rmd** Description: Compiles and visualizes the heating rate data collected in the lab. Also visualized the spectral data collected in the lab, and from the literature. Requires: * heatingrate_chamber.csv * heatingrate_open.csv * spectraldata.csv * spectraldatalinear.csv * spectraldataexp.csv * ASTMG173.csv **File: 2_FieldDataAnalysis.Rmd** Description: Runs the analyses for the field data. Requires: * fielddat_ibuttoncorrelation.csv * fielddat_ibutton95max.csv * FLIRData.csv ## DATASETS **Data: heatingrate_chamber.csv** Description: Heating rate data for small frog models (high and low NIR reflectance) collected in the lab in a chamber that controls for convection and conduction. temp: Temperature (Celcius) from thermocouple treatment: Coating type, high (High_NIR) or low (Low_NIR) near infrared reflectance temp_type: Recording location, surface (sur_temp) or internal ...许多在绿叶背景下呈现隐蔽色的绿色动物，其近红外（NIR）反射率也与叶片一致。由于动物无法感知近红外光，因此这种近红外背景匹配不太可能起到视觉伪装的作用。目前已提出两种备选解释——红外伪装（infrared camouflage，即匹配背景温度）与体温调节（thermoregulation）——但二者均未经过实验验证。为验证上述假说，我们开发了可独立调控近红外反射率与可见光反射率的涂层。我们制备了琼脂蛙模型，用以模拟不同叶栖蛙类的反射特性：这些蛙类外观呈绿色，但近红外反射率差异显著。我们分别在实验室（使用太阳模拟器）与叶栖蛙类的自然栖息地——热带雨林中，对比了高、低近红外反射率蛙模型的升温速率与温度（表面温度与核心温度）。在实验室中，低近红外反射率的琼脂蛙模型…… # 叶栖蛙类的红外伪装：关于适应性趋同的一则警示案例 **文件：1_LabDataAnalysis.Rmd** 描述：编译并可视化实验室采集的升温速率数据，同时可视化实验室及文献中采集的光谱数据。 依赖文件： * heatingrate_chamber.csv * heatingrate_open.csv * spectraldata.csv * spectraldatalinear.csv * spectraldataexp.csv * ASTMG173.csv **文件：2_FieldDataAnalysis.Rmd** 描述：对野外采集的数据进行分析。依赖文件： * fielddat_ibuttoncorrelation.csv * fielddat_ibutton95max.csv * FLIRData.csv ## 数据集 **数据集：heatingrate_chamber.csv** 描述：实验室中在控制对流与传导的环境舱内采集的小型蛙模型（高、低近红外反射率）的升温速率数据。 字段说明： temp：热电偶采集的温度（摄氏度） treatment：涂层类型，高近红外反射率（High_NIR）或低近红外反射率（Low_NIR） temp_type：记录位置，表面（sur_temp）或内部……