Shell colouration is associated with sex, boldness, and innate immunity in wild adult eastern box turtles (Terrapene carolina carolina)
Data files
Jul 11, 2025 version files 48.52 KB
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README.md
11.65 KB
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Warren_Klukowski_BoxTurtle_Data.xlsx
36.87 KB
Abstract
Animal colouration often plays a role in intraspecific communication. The badges of lizards and ornaments of birds are frequent examples of honest signals regarding physiological condition and behaviour. Turtles share evolved characteristics with both non-avian and avian reptiles and many express colour markings on the shell and head, yet the significance of colouration in turtles remains unclear. We assessed aspects of shell colouration (carapace spot hue, saturation, and brightness and percent melanism of the carapace and plastron) in adult eastern box turtles (Terrapene carolina carolina) from a wetland population and explored their association with age, sex, boldness, haemolysis capabilities, plasma triglycerides, plasma corticosterone, and body condition. We found evidence of varying bold temperaments based on high among- and low within- individual variation across several behaviours during and after handling. Findings further suggested that separate aspects of shell colouration were associated with sex, boldness temperament, and innate immunity. Specifically, males exhibited redder carapace spots than females, bolder turtles exhibited brighter carapace spots and less melanic (more spotted) plastrons, and turtles with higher in vitro haemolysis scores tended to have more saturated carapace spots. These associations suggest potential roles for shell colouration to signal aspects of behaviour and immune function, however, we discuss limitations arising from our methods such as the use of a single blood sample for physiological metrics. Further studies on these associations are needed to determine their stability, underlying mechanisms, and ecological implications.
by Warren & Klukowski
Description of the Data and file structure
The Excel data file 'Warren_Klukowski_BoxTurtle_Data.xlsx' has three sheets containing some similar and some different data depending on their intended purpose / analysis. The first sheet contains the data from all behavioural assays (along with turtle characteristics and assay conditions) and is used for calculating the repeatability of these behaviours using GLMMs as well as testing the effects of turtle characteristics and assay conditions on the behaviours. The second sheet contains averages and one-time measures used to conduct the GLMs testing for the effects of (1) sex, age, and mean compiled boldness score on each of the colouration metrics (spot hue, spot saturation, spot brightness, plastron percent melanism, and carapace percent melanism), and (2) sex, mean compiled boldness score, and all colouration metrics on each of the physiological metrics (triglycerides, hemolysis, corticosterone, and vBCI). The third sheet contains information on pinch force and temperature differentials collected during this study from these same turtles but which is not discussed in the main manuscript published in AMRE and is only included for potential future use.
NOTE: In the Excel data file, cells containing 'NA' represent data points that are not available as they were failed to be collected during that specific assay for that particular individual turtle. The blank for cell G120 on sheet#1 (All_Assays_For_Repeatability) is also one of these missing data points but has been left blank to allow the R script to run appropriately when conducting the GLMM on this variable.
Sheet #1 "All_Assays_For_Repeatability" headers:
- "id" and "subject": corresponds with individual turtles. The Rscript utilizes "id" but either is fine. Note that all 28 turtles were tested across 4 to 5 assays.
- "EyeEmerge": The latency (in seconds) the turtle took to extend the head so that the eyes surpassed the margins of the shell during the 10-min observation period (note: turtle was assigned a minimum of 1 if immediately emerged and maximum of 600 if didn't at all).
- "TwobodyLengths": The latency (sec) the turtle took to move 2-body lengths during the observation period (was assigned a minimum of 1 if immediately emerged and maximum of 600 if didn't at all).
- "OneMeterMoveLatency": The latency (sec) the turtle took to move 1 meter during the observation period (was assigned a minimum of 1 if immediately emerged and maximum of 600 if didn't at all).
- "OneMeterMoveScore": The yes/no scoring of one meter movement based on whether the turtle did or did not move 1 m during the observation period for that assay (0 = no, 0.5 = yes).
- "TimeClosedUpDuringHandling_s": The amount of time (sec) the turtle spent closed up during the 3-min handling period (was assigned a minimum of 1 if closed up the whole time, and maximum of 180 if didn't close up at all).
- "KicksScore": Represents whether the turtle did (0.5) or did not (0) kick with the limbs ("air walk") during the 3-min handling period.
- "FinalScore": Represents the turtle's compiled boldness score for that assay, calculated using rankings from the behaviours above. See methods and table 1 in AMRE publication for details on this score.
- "FinalScoreAvg": Represent the mean compiled boldness score for turtles across all assays.
- "testtime": The time of day that the assay took place.
- "skycode": A ranking of cloud coverage and rainfall conditions during the assay (see methods in AMRE pub).
- "testn": The number of assays for that turtle (1 - 5).
- "irshelltemp" The infrared surface temperature (°C) of the turtle's carapace taken just prior to the start of the assay.
- "sex": The sex of the turtle based on plastron indentation, where F = female and M = male.
- "ageBC": The estimated age (years) of the turtle based on counts of annuli (scute rings).
- "vBCI": The volumetric body condition of the turtle calculated using morphometric measures (see methods in AMRE pub).
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Sheet #2 "Avgs_single_measures_colour" headers:
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"TurtleID": ID of the turtle.
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"AvgEyeEmergeLat": Represent the mean eye emergence latency (sec) for turtles across all assays.
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"AvgCompiledBoldnessScore": Represent the mean compiled boldness score for turtles across all assays.
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"Corticosterone_ng_ml": The turtle's plasma corticosterone levels (ng/ml).
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"Triglycerides_mg_ml": The turtle's plasma triglycerides levels (mg/ml).
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"HemolysisScore": The turtle's hemolysis score (see methods in AMRE pub).
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"Sex": The sex of the turtle based on plastron indentation, where F = female and M = male.
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"EstimateAge": The estimated age (years) of the turtle based on counts of annuli (scute rings).
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"Weight_g": The turtle's weight in grams.
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"CarapaceLength_mm": The length (mm) of the turtle's carapace.
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"CarapaceWidth_mm": The width (mm) of the turtle's carapace.
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"CarapaceHeight_mm": The height (mm) of the turtle's carapace.
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"vBCI": The volumetric body condition of the turtle calculated using morphometric measures, including weight, shell length, width, and height (see methods in AMRE pub).
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"CarapaceMelanismPercent": The percent of dark melanistic background (excluding spots) making up the carapace.
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"PlastronMelanismPercent": The percent of dark melanistic background (excluding spots) making up the plastron.
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"CarapaceHue": The calculated mean hue of carapace conspicuous spots.
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"CarapaceSaturation": The calculated mean saturation of carapace conspicuous spots.
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"CarapaceBrightness": The calculated mean brightness of carapace conspicuous spots.
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"BleedTimeofDay": The time of day that a blood sample was collected from the turtle.
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"TimetoBleed_s": The duration of time (in sec) that it took to bleed the turtle.
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"testost": results on plasma testosterone levels (ng/ml) not evaluated in this study due to low sample size.
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"Progest": results on plasma progestone levels (ng/ml) not evaluated in this study due to low sample size.
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Sheet #3 "Avgs_For_PinchForce" headers:
- "ID": ID of the turtle.
- "PinchForce_kg": The maximum pinch force (kg) measured from the turtle at the anterior gap of the shell following the final behavioral assay using a a pinch gauge dynamometer and poking and prodding the skin of the turtle's snout and forelimbs to elicit voluntary closure.
- "AvgEyeEmergeLat": The mean eye emergence latency (sec), or time in seconds for the turtle to emerge the head so that the eyes surpassed the anterior margins of the carapace during the 10-minute observation period, for turtles across all assays.
- "AvgFinalScore": The mean compiled boldness score for turtles across all assays.
- "LMBoldCateg": Represents the placement of turtles into either "bolder" (AvgFinalScore ≥ 2) or "shier" categories (AvgFinalScore < 2).
- "Willing_Able_to_Close": Represents the placement of turtles into one of two categories concerning their perceived 'willingness' to close the shell during the collection of pinch force measures: (1) "Quick/Able" for turtles that quickly and tightly closed the shell, or (2) "Reluctant/Unable" for turtles noted as highly reluctant (e.g., behaviorally pushed back and bit at gauge) or seemingly unable (e.g., lacked the ability to close completely) to close.
- "FinalAssayEmergeLat": The observed eye emergence latency (sec) for turtles during their final behavioral assay test, just before pinch force measures were collected (note: turtle was assigned a minimum of 1 if immediately emerged and maximum of 600 if didn't at all).
- "Sex": The sex of the turtle based on plastron indentation, where F = female and M = male.
- "AgeClass": Placement of turtles into age class 1 (10 - 14 years old), class 2 (15 - 19 years old), or class 3 (20+ years old).
- "AgeBestCount": The estimated age (years) of the turtle based on counts of annuli (scute rings).
- "Weight_g": The turtle's weight in grams.
- "CarapaceLength_mm": The straight-line length (mm) of the turtle's carapace measured dorsally down the midline (i.e., from the anterior-most marginal scute to the posterior-most marginal scute) of the carapace using manual calipers.
- "CarapaceWidth_mm": The maximum width (mm) of the turtle's carapace measured ventrally using manual calipers.
- "CarapaceHeight_mm": The maximum height (mm) of the turtle's carapace measured laterally using manual calipers.
- "vBCI": The volumetric body condition of the turtle calculated using morphometric measures, including weight, shell length, width, and height (see methods in AMRE pub).
- "AvgWristEm": The mean wrist emergence latency (sec), or time in seconds for the wrist to emerge during the 10-minute observation period of the behavioral trial, for turtles across all their assays.
- "Avg2BodyLengths": The mean 2-body length movement latency (sec), or time in seconds for the turtle to reach 2-body lengths in distance during the 10-minute observation period of the behavioral trial, for turtles across all their assays.
- "Avg1mMoveLat": The mean 1 m movement latency (sec), or time in seconds for the turtle to reach at least 1 m in distance during the 10-minute observation period of the behavioral trial, for turtles across all their assays.
- "AvgTotDef": The mean number of defensive behaviors recorded during the 3-minute handling period for turtles across all their assays.
- "FinalDay_IR_ShellTemp": The observed shell temperature (°C) of the turtle measured just before the final behavioral assay using a handheld infrared temperature reader.
- "FullStudyTempDifferential": The temperature (°C) differential of turtles calculated as the difference between the average shell temperature (captured every 30-minutes via an iButton affixed to the carapace) and the average soil surface temperature (captured every 30-minutes via an iButton placed on the soil surface of a nearby shaded region of the wetland) across the total time of the turtle's involvement in the study.
- "DayTimeTempDifferential": The temperature (°C) differential of turtles calculated as the difference between the average shell temperature (captured every 30-minutes via an iButton affixed to the carapace) and the average soil surface temperature (captured every 30-minutes via an iButton placed on the soil surface of a nearby shaded region of the wetland) during only the daytime portions (0900-1700 h) of the turtle's involvement in the study.
- "NightTimeTempDifferential": The temperature (°C) differential of turtles calculated as the difference between the average shell temperature (captured every 30-minutes via an iButton affixed to the carapace) and the average soil surface temperature (captured every 30-minutes via an iButton placed on the soil surface of a nearby shaded region of the wetland) during only the nighttime portions (2300-0500 h) of the turtle's involvement in the study.
The included R script file ("RScript_BoxTurtles_Warren_Klukowski") shows how we analyzed these data. Comments within the R script will inform you on which excel sheet to have active for certain analyses. We swapped between active excel sheets by opening the excel data document and manually moving the desired sheet to be the first in the order of sheets, then we would save that excel document and have R Studio read it again to import that particular dataset.
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