Data from: Infrared camouflage in leaf-sitting frogs: A cautionary tale on adaptive convergence
Data files
Feb 12, 2025 version files 2.57 MB
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ASTMG173.csv
33.47 KB
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fielddat_ibutton95max.csv
4.78 KB
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fielddat_ibuttoncorrelation.csv
227.29 KB
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FLIRData.csv
6.78 KB
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heatingrate_chamber.csv
73.16 KB
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heatingrate_open.csv
42.99 KB
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README.md
6.80 KB
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spectraldata.csv
441.97 KB
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spectraldataexp.csv
1.02 MB
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spectraldatalinear.csv
711.51 KB
Abstract
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 reflectance heated up more quickly and reached higher temperatures than those with high NIR reflectance. However, in the field, there was no significant difference between high and low NIR treatments in the similarity of surface temperature to the adjacent leaves or in core temperature, thus failing to support the infrared camouflage and thermoregulation hypotheses, respectively. The lack of difference between treatments is likely due to the limited exposure of frogs to direct solar radiation in their natural habitats. We propose a non-adaptive explanation for NIR background matching based on specific mechanisms underlying green coloration and translucence in frogs and caution against assuming 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 (in_temp)
time: Actual time (hours:minutes:seconds)
filter: Lighting condition: full spectrum (ALL), nearinfrared only (NIR) or UV-VIS only (UV_VIS)
time_order1: Time since start of experiment in seconds
temp_diff_withair: Difference in temperature between the model and air temperature (C)
Data: heatingrate_open.csv
Description: Heating rate data for all frog models (high and low NIR reflectance) collected outside of the chamber, therefore does not control for convection and conduction.
temp: Temperature (Celcius) from thermocouple
treatment: Coating type and size. LHNIR: Large, high NIR; LLNIR: Large, low NIR; SHNIR: Small, high NIR; SLNIR: Small, low NIR; LUN: Large uncoated; SUN: small, uncoated.
temp_type: Recording location, surface (sur_temp) or internal (in_temp)
time: Actual time (hours:minutes:seconds)
filter: Lighting condition: full spectrum (ALL), nearinfrared only (NIR) or UV-VIS only (UV_VIS)
time_order1: Time since start of experiment in seconds
size: Model size, Small or Large
NIRtreatment: NIR coating type: High NIR, Low NIR or Uncoated
Data: spectraldata.csv
Description: Reflectance data from our model frogs, recorded in the lab, as well as spectral data of real leaf sitting frogs, collected from the literature.
wl: wavelength (nanometers)
refl: reflectance as proportion (max = 1; min = 0), relative to a white standard.
se: standard error, only for model frog measurements
species: species name or if it is a model frog.
NIR: Whether it has low or high NIR reflectance
type: Model or Real species
treatment: Combination of NIR classification and species classification
Data: spectraldatalinear.csv
Description: As above but has the linear decline in reflectance added for wavelengths beyond 950nm.
Data: spectraldataexp.csv
Description: As above but has the exponential decline in reflectance added for wavelengths beyond 950nm.
Data: ASTMG173.csv
Description: Irradiance spectrum of sunlight ASTM G-173
Wvlgth nm: Wavelength in nanometers
Global tilt Wm-2nm-1: Irradiance in watts per meter squared per nanometer
Data: fielddat_ibuttoncorrelation.csv
Description: iButton data paired together based on frog pairs in the field. That is, to determine whether one type of frog in each pair is consistently warmer or cooler than the other type of frog, we have reorgansied the dataset so these temperatures are linked (xaxis and yaxis values).
uqID: There are mulitple measurements for each individual frog on each day. This variable links measurements from the same frog on a particular day.
xaxis: If Group is a coated group (L or S), this is the temperature of the low NIR frog. If Group is uncoated (U), this is the temperature of the small NIR frog.
yaxis: If Group is a coated group (L or S), this is the temperature of the high NIR frog. If Group is uncoated (U), this is the temperature of the large NIR frog.
Date.Time: Date and time from ibutton
SiteID: Five sites were selected each day for three days (i.e. 15 sites). This variable links measurements from frogs at each site (one of each frog type)
PairID: Model frogs were placed in the field in pairs. This variable links paired frog models.
Group: For pairs were either large low and high NIR (L), small low and high NIR (S) or uncoated small and large (U). This variable shows these groupings.
airtemp: Air temperature at that site at the same time as the model temperatures
Data: fielddat_ibutton95max.csv
Description: For each model for each day in the field, this dataset has the 95th percentile temperature. This is a proxy for the maximum temperature reached.
SiteID: Five sites were selected each day for three days (i.e. 15 sites). This variable links measurements from frogs at each site (one of each frog type)
uqID: There are mulitple measurements for each individual frog on each day. This variable links measurements from the same frog on a particular day.
PairID: Model frogs were placed in the field in pairs. This variable links paired frog models.
Group: For pairs were either large low and high NIR (L), small low and high NIR (S) or uncoated small and large (U). This variable shows these groupings.
NIR: Type of NIR coating, low NIR reflectance, high NIR reflectance or uncoated.
Size: Size of frog, small or large
iButtonID: iButtons were placed in an individual frog model and used for three consecutive days. This variable links measurements from the same iButton.
max95: The is the 95th percentile (maximum) for each day for each frog model.
maximum: This is the overall maximum temperature for each day for each model.
max95air: This is the 95th percentile for airtemperature at each site.
Data: FLIRData.csv
Description: Surface temperature for model frogs, extracted from thermal images.
Date: Date image was taken
SiteID: Five sites were selected each day for three days (i.e. 15 sites). This variable links measurements from frogs at each site (one of each frog type)
Time: whether image was taken in the morning (am) or afternoon (pm)
PairID: Model frogs were placed in the field in pairs. This variable links paired frog models.
Group: For pairs were either large low and high NIR (L), small low and high NIR (S) or uncoated small and large (U). This variable shows these groupings.
IR.image: number of infrared photograph
DC.image: number for colour photograph
Notes: Notes regarding image and data extraction
Delete: Data that needs to be filtered out (Y) or not (N)
Temp_LNIR: Surface temperature (Celcius) of the low NIR reflectance frog
Temp_HNIR: Surface temperature (Celcius) of the High NIR reflectance frog
Temp_UCL: Surface temperature (Celcius) of the large uncoated frog
Temp_UCS: Surface temperature (Celcius) of the large uncoated frog
Temp_env: Surrounding environment temperature (i.e. leaf temperature)