Data for: Size-dependent colouration balances conspicuous aposematism and camouflage
Data files
Sep 13, 2023 version files 886.15 MB
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01_Spectrophotmetry_Frog.zip
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02_Spectrophotometry_Background.zip
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03_Internal_contrast.txt
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04_Detection_Exp01.txt
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05_Detection_Exp02.txt
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06_RawImages.zip
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README.md
Abstract
Colour is an important component of many different defensive strategies, but signal efficacy and detectability will also depend on the size of the coloured structures, and how pattern size interacts with the background. Consequently, size-dependent changes in colouration are common among many different species as juveniles and adults frequently use colour for different purposes in different environmental contexts. A widespread strategy in many species is switching from crypsis to conspicuous aposematic signalling as increasing body size can reduce the efficacy of camouflage, while other antipredator defences may strengthen. Curiously, despite being chemically defended, the gold-striped frog (<i>Lithodytes lineatus</i>, Leptodactylidae) appears to do the opposite, with bright yellow stripes found in smaller individuals whereas larger frogs exhibit dull brown stripes. Here, we investigated whether size-dependent differences in colour support distinct defensive strategies. We first used visual modelling of potential predators to assess how colour contrast varied among frogs of different sizes. We found that contrast peaked in mid-sized individuals while the largest individuals had the least contrasting patterns. We then used two detection experiments with human participants to evaluate how colour and body size affected overall detectability. These experiments revealed that larger body sizes were easier to detect, but that the colours of smaller frogs were more detectable than those of larger frogs. Taken together our data support the hypothesis that the primary defensive strategy changes from conspicuous aposematism to camouflage with increasing size, implying size-dependent differences in the efficacy of defensive colouration. We discuss our data in relation to theories of size-dependent aposematism and evaluate the evidence for and against a possible size-dependent mimicry complex with sympatric poison frogs (Dendrobatidae).
README: Data for: Size-dependent colouration balances conspicuous aposematism and camouflage
https://doi.org/10.5061/dryad.4xgxd25cf
James B. Barnett, Justin Yeager, Brendan L. McEwen, Isaac Kinley, Hannah M. Anderson, & Jennifer Guevara.
For further information contact:
James B. Barnett
Email: barnettdata@gmail.com
Web: www.jbbarnett.co.uk
Description of the data and file structure
SPECTROPHOTOMETRY DATA
Data files:
01_Spectrophotometry_Frog.txt
02_Spectrophotometry_Background.txt
Format: compressed (.zip) folders containing multiple tab-delimited text (.txt) files
export format generated automatically by Ocean Optics Flame S-XR1-ES spectrophotometer (Ocean Optics Inc. USA)
(appropriate for use with R package pavo 2 (Maia et al. 2019. Methods Ecol. Evol. 10:1097-1107, doi = {10.1111/2041-210X.13174}))
File identification:
Spectrophotometry_Frog: file name prefixes refer to frog colour patches (Black = dorsum, Red = Spot, Yellow = Stripe)
Spectrophotometry_Background: file name prefixes refer to leaves of different colours (Beige, Black, Green, or Red)
number following prefix refers to the leaf replicate (1-10)
file name suffix refers to repeat measure for each leaf (1-3)
(e.g.\, "Red-02_Reflection_003.txt" = red leaf number 2\, 3rd measurement | "Green-10_Reflection_002.txt" = green
leaf number 10, 2nd measurement)
VISUAL MODELLING DATA
Data file:
03_Internal_contrast.txt
Format: tab-delimited text
Column identification:
visual_model: visual model used in the analysis (peafowl LMS)
species: study species ("Lithodytes_lineatus")
frog_number: unique number for each frog (1:30)
SVL_mm: snout-vent length (SVL) of each frog in millimetres
colour_contrast: colour comparison (yellow = stripe vs dorsum | red = spot vs dorsum)
dS: chromatic contrast
dL: achromatic contrast
DETECTION DATA
Data files:
04_Detection_Exp01.txt
05_Detection_Exp02.txt
Format: tab-delimited text
Column identification:
expt: experiment number (1 or 2)
file: unique code for each human participant (randomly generated during anonymous trial)
rt_ms: reaction time in seconds (time taken to click on the frog)
is_hit: TRUE = correct click on frog, FALSE = frog not found
cond_1: frog age class (S = small, M = Medium, L = Large)
cond_2: colour condition treatment (A = dorsal only, B = dorsal & spots, C = dorsal & stripe, D = dorsal, spot, & stripe)
cond_3: frog size in millimetres (exp 1 = 35 | exp 2 = 20\, 35\, or 50)
trial_idx: replicate number for each participant (1-48 trials)
cond: combination of cond_1 & cond_2
RAW IMAGE FILES
Data files:
06_RawImages.zip (contains 30 image files, e.g., "01_DSC_1289.NEF")
Format: .NEF Nikon RAW Image
** NB ** Codes within photographs (e.g., "LLI03") are from encounter surveys and includes frogs not sampled for colour analysis. Instead, 'frog_number' as reported in the VISUAL MODELLING DATA (see above) is denoted in the file name (e.g., "03_DSC_1333.NEF").