DOI: 10.5061/dryad.1zcrjdfzq
title: Melanistic coloration does not influence thermoregulation in the crepuscular gecko Eublepharis macularius

description: Body coloration in ectotherms serves multiple biological functions,
 including avoiding predators, communicating with conspecific individuals,
 and involvement in thermoregulation. As ectotherms rely on environmental
 sources of heat to regulate their internal body temperature, stable
 melanistic body coloration or color change can be used to increase or
 decrease heat absorption and heat exchange with the environment. While the
 function of melanistic coloration for thermoregulation increases solar
 radiation absorption for heating in many diurnal ectotherms, research on
 crepuscular and nocturnal ectotherms is lacking. Since crepuscular and
 nocturnal ectotherms generally absorb heat from the substrate, in these
 organisms melanistic coloration may have other primary functions besides
 thermoregulation. As such, in this work, we hypothesized that the
 proportion of dorsal melanistic body coloration would not influence
 heating and cooling rates in the crepuscular gecko, Eublepharis
 macularius, and that changes in environmental temperature would not
 trigger color changes in this species. Temperature measurements of the
 geckos and of the environment were taken using infrared thermography and
 temperature loggers. Color data were obtained using objective photography
 and a newly developed custom software package. We found that body
 temperature reflected substrate temperatures, and that the proportion of
 melanistic coloration has no influence on heating or cooling rates or on
 color changes. These findings support that melanistic coloration
 in E. macularius may not be used for thermoregulation and
 strengthen the hypothesis that in animals active in low light conditions,
 melanistic coloration may be used instead for camouflage or other
 functions.
description: Melanistic color data for each gecko were obtained by taking
 visible images using a full spectrum converted Canon 1300D with a Kolari
 Vision UV/IR cut filter (410-700nm transmission). Melanistic color pattern
 was then extracted from the images following a newly developed software
 pipeline. Step-by-step data color extraction protocol can be found at
 https://github.com/brandon-hastings/Lumeleon Body temperature of each gecko has been obtained using an infrared camera (CAT S62 smartphone Pro camera). 
description: # Melanistic coloration does not influence thermoregulation in the
 crepuscular gecko Eublepharis macularius The datasets described here are a
 combination of temperature measurements collected from both iButton
 sensors and FLIR thermal imaging, visible color values from multispectral
 photography, and physical characteristics (body length, mass, etc.). ##
 Software used: * R v4.2.1 for statistical analysis, with required packages
 loaded at the top of the included *final\_gecko\_script.R* ## Description
 of data files: ### FinalGeckoData.csv Describes measurements collected
 from each individual during the experiments. All temperature measurements
 are in degrees Celsius. Luminance (the measure of light intensity per
 pixel) is represented as a pixel value ranging from 0-255, with 0 being
 the darkest and 255 being the lightest. Empty cells are due to missing
 data in data collection at that time period (specifically the body temp,
 substrate, and atmospheric measurements). Warm/cold/hide before and after
 measurements will always have an empty value corresponding to the
 beginning and end of each experiment, respectively. Individual EMM001 at
 time 4 has an empty value for Dark spot luminance because the clustering
 algorithm did not detect melanistic coloration in that image. Variables
 are described as follows: * **ID**: The unique identification number
 assigned to each individual tested. * **Average melanistic proportion**:
 the average amount of melanistic proportion for each individual,
 calculated as the mean of Dark proportion. * **Date tested**: The date on
 which individuals were tested. Ex. 802 = August, 02 * **Time**: The
 timepoint at which measurements were taken. 1 corresponds to the first
 measurements taken at the start of each experiment. * **Light spot
 luminance**: The average luminance pixel value calculated from the
 non-melanistic coloration of an individual. * **Dark spot luminance**: The
 average luminance pixel value calculated from the melanistic coloration of
 an individual. * **Light Proportion**: The proportion of non-melanistic
 coloration relative to the dorsal area of the entire individual. * **Dark
 Proportion**: The proportion of non-melanistic coloration relative to the
 dorsal area of the entire individual. * **Warm side**: The temperature
 reading from the iButton placed over the heating pad at the time of
 capturing images. * **Warm 5 min before**: The temperature reading from
 the iButton placed over the heating pad 5 minutes before capturing images.
 * **Warm 5 min after**: The temperature reading from the iButton placed
 over the heating pad 5 minutes after capturing images. * **Cold side**:
 The temperature reading from the iButton placed at the far end of the
 terrarium away from the heating pad at the time of capturing images. *
 **Cold 5 min before**: The temperature reading from the iButton placed at
 the far end of the terrarium away from the heating pad 5 minutes before
 capturing images. * **Cold 5 min after**: The temperature reading from the
 iButton placed at the far end of the terrarium away from the heating pad 5
 minutes after capturing images. * **Hide**: The temperature reading from
 the iButton placed underneath of the hide at the time of capturing images.
 * **Hide 5 min before**: The temperature reading from the iButton placed
 underneath of the hide 5 minutes before capturing images. * **Hide 5 min
 after**: The temperature reading from the iButton placed underneath of the
 hide 5 minutes after capturing images. * **Body temp**: The body
 temperature of the individual at the time of image capture, calculated via
 the average eye temperature obtained from thermal imaging. *
 **Substrate**: The substrate temperature of the terrarium flooring
 obtained from thermal imaging. * **Atmospheric**: The temperature reading
 from the iButton placed next to the terrarium at the time of capturing
 images. ### GeckoInfo.csv Describes measurements collected from each
 individual before testing. Variables are described as follows: * **ID**:
 The unique identification number assigned to each individual tested. *
 **Sex**: The sex of the individual. * **Average melanistic proportion**:
 the average amount of melanistic proportion for each individual, taken
 from the previous data file. * **Mass**: the mass in grams of an
 individual, obtained via a digital balance used before the start of the
 experiment. * **SVL**: The Snout-vent-length of each individual, measured
 before the start of the experiment. \**average melanistic proportion* was
 included in GeckoInfo.csv for ease of use in the statistical code, but was
 calculated from images taken during the experiment.