Data from: Adaptation in the Anthropocene: How behavioural choice and colour change enables chameleon prawns to camouflage on non‐native seaweeds
Data files
Nov 11, 2024 version files 169.46 KB
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background_matching_dataset.xlsx
50.68 KB
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behavioural_choices_dataset.xlsx
17.82 KB
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colour_change_dataset.xlsx
90.62 KB
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README.md
10.34 KB
Abstract
Animals combine colour change and behavioural choices to enhance concealment and adapt to changes in habitat in time and space. However, non‐native and invasive habitat‐forming plants and seaweeds can change the landscape, challenging animals to remain camouflaged, especially when the colour of the new habitat differs from the native backgrounds.The chameleon prawn (Hippolyte varians) exhibits remarkable colour variation and effective camouflage against different native seaweeds in shallow tidepools. Individuals optimize crypsis by choosing colour‐matching seaweeds and changing colour over time. In some locations, the prawn's native habitats are now replaced by non‐native seaweeds of different coloration and structure, making it important to understand whether substrate choice and colour change facilitates the occupation of these seaweeds and enables prawns to camouflage against new backgrounds.Using image analysis and visual modelling of a fish predator, we assessed the colour variation and camouflage of chameleon prawns occupying the non‐native seaweeds brown wireweed (Sargassum muticum) and pink harpoon weed (Asparagopsis armata) in southwest UK. We performed laboratory trials to examine whether prawns maintain their preference for colour‐matching native substrates when given a choice between them and non‐native seaweeds, and if they can change their coloration to improve camouflage against non‐native substrates.Prawns exhibit phenotypic diversity and camouflage that varied with the non‐native seaweed species, with low colour variation and effective camouflage on pink harpoon weed, but high colour diversity and reduced concealment against brown wireweed. Prawns choose non‐native seaweeds when the alternative native substrate provides mismatching coloration, but they did not exhibit any preference between colour‐matching native and non‐native seaweeds. Once in non‐native habitats, prawns change their appearance over a few days to match the background, sometimes faster than when changing on native seaweeds of contrasting coloration.Although human activities considerably modify the coloration of marine landscapes by increasing the establishment of non‐native seaweeds, the impacts of those changes appear less severe for colour‐changing species, such as chameleon prawns, and will depend on the similarity between the colour of the new substrates and the original native backgrounds, and how animals use behaviour and physiology to match new habitats.
https://doi.org/10.5061/dryad.xpnvx0kr0
Description of the data and file structure
Codes and data for the manuscript “Adaptation in the Anthropocene: how behavioural choice and colour change enables chameleon prawns to camouflage on non-native seaweeds”.
Authors: Rafael Campos Duarte; Beks Ryan; Gustavo Muniz Dias; and Martin Stevens
Contact: Rafael Campos Duarte, rafaduarte87@gmail.com / rafael.duarte@ua.pt
Using image analysis and visual modelling of a fish predator, we assessed the colour variation and camouflage of chameleon prawns (Hippolyte varians) occupying the non-native seaweeds brown wireweed (Sargassum muticum) and pink harpoon weed (Asparagopsis armata) in southwest UK. We performed laboratory trials to examine whether prawns maintain their preference for colour-matching native substrates when given a choice between them and non-native seaweeds, and if they can change their coloration to improve camouflage against non-native substrates. We found that prawns exhibited phenotypic diversity and camouflage that varied with the non-native seaweed species, with low colour variation and effective camouflage on pink harpoon weed, but high colour diversity and reduced concealment against brown wireweed. Prawns chose non-native seaweeds when the alternative native substrate provided mismatching coloration, but they did not exhibit any preference between colour-matching native and non-native seaweeds. Once in non-native habitats, prawns changed their appearance over a few days to match the background, sometimes faster than when changing on native seaweeds of contrasting coloration.
Date of data collection: October 2022 - May 2023
Location: Gyllyngvase and Castle beaches, Falmouth, Cornwall, UK (50°08′33″N, 05°04′08″W)
Responsible for field collections: Rafael Campos Duarte; Beks Ryan
Responsible for writing the codes: Rafael Campos Duarte
Files and variables
File: background_matching_dataset.xlsx
Description: This dataset describes the luminance, colour and saturation in the RNL chromaticity space of seaweeds and chameleon prawns (Hippolyte varians) sampled from the non-native seaweeds pink harpoon weed (Asparagopsis armata) and brown wireweed (Sargassum muticum) to the view of the goby fish Gobiusculus flavescens. The dataset also contains the prawn coloration in the human-based Lab visual space.
Variables
- image: the code used to identify each photograph
- seaweed: either the seaweed itself or the seaweed where the prawn was sampled (sm for brown wireweed and hw for pink harpoon weed)
- id: the identification code of each individual
- date: the date of prawn sampling (empty cells-NA for the seaweeds)
- size: the size (in mm) of the prawn individual (empty cells-NA for the seaweeds)
- type: either seaweed or prawn
- lum_mean: the mean value of the luminance measured from all ROI (region of interest) pixels
- lum_dev: the standard deviation of the luminance measured from all ROI pixels
- rnl_x_mean: the mean value of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_x_dev: the standard deviation of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_y_mean: the mean value of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_y_dev: the standard deviation of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_saturation_mean: the mean value of the saturation channel measured from all ROI pixels
- rnl_saturation_dev: the standard deviation of the saturation channel measured from all ROI pixels
- L: the values of Lightness from the Lab colour space
- A: the values of the green-red colour component from the Lab colour space
- B: the values of the yellow-blue colour component from the Lab colour space
File: behavioural_choices_dataset.xlsx
Description: This dataset describes the choice of chameleon prawns (Hippolyte varians) between native (the green sea lettuce Ulva lactuca and the red dulse Palmaria palmata) and non-native seaweeds (the pink harpoon weed Asparagopsis armata and the brown wireweed Sargassum muticum) according to the colour of the prawn (green or red), the identity of the non-native seaweed (pink harpoon weed or brown wireweed) and the level of colour matching between the prawn and the native seaweed (match or mismatch). Prawn choice was measured twice as the first choice and the choice after 10 minutes.
Variables
- type: the colour of the prawn (green - g or red - r)
- comparison: the comparison between the seaweeds made in the trial (red dulse - d, pink harpoon weed - hw, green sea lettuce - sl, brown wireweed - sm)
- non_native: the non-native seaweed species (hw or sm)
- native_match: the colour match between the prawn and the native seaweed offered in the trial (match - 1 or mismatch - 0)
- fist_choice: the initial seaweed choice made by the prawn (d, sl, hw or sm)
- ten_minutes: the seaweed chosen by the prawn after 10 minutes (d, sl, hw or sm)
missing data: NA
File: colour_change_dataset.xlsx
Description: This dataset contains two spreadsheets. The first describes the luminance and colour change in the RNL chromaticity space of green and red chameleon prawns (Hippolyte varians) maintained for 30 days in colour-mismatching native seaweeds (red dulse Palmaria palmata for green prawns and green sea lettuce Ulva lactuca for red prawns) and the non-native seaweeds pink harpoon weed (Asparagopsis armata) and brown wireweed (Sargassum muticum). The second spreadsheet contains information about the luminance and colour in the RNL chromaticity space of the four different seaweeds used in the experiment.
Variables
prawn_data_rnl
- type: the colour of the prawn (green - g or red - r)
- id: the identification code of each individual
- seaweed: the seaweed species where the prawn was maintained over the experiment (red dulse - d, pink harpoon weed - hw, green sea lettuce - sl, brown wireweed - sm)
- day: the day since the start of the trial when the photograph was taken (0, 5, 10, 15, 20, 25 or 30)
- lum_mean: the mean value of the luminance measured from all ROI (region of interest) pixels
- lum_dev: the standard deviation of the luminance measured from all ROI pixels
- rnl_x_mean: the mean value of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_x_dev: the standard deviation of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_y_mean: the mean value of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_y_dev: the standard deviation of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_saturation_mean: the mean value of the saturation channel measured from all ROI pixels
- rnl_saturation_dev: the standard deviation of the saturation channel measured from all ROI pixels
- LAB_CIE L_Mean: the values of Lightness from the Lab colour space
- LAB_CIE A_Mean: the values of the green-red colour component from the Lab colour space
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LAB_CIE B_Mean: the values of the yellow-blue colour component from the Lab colour space
- size: the size (in mm) of the prawn individual
seaweed_data_rnl
- seaweed: the seaweed species (red dulse - d, pink harpoon weed - hw, green sea lettuce - sl, brown wireweed - sm)
- id: the identification code of each seaweed sample
- lum_mean: the mean value of the luminance measured from all ROI (region of interest) pixels
- lum_dev: the standard deviation of the luminance measured from all ROI pixels
- rnl_x_mean: the mean value of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_x_dev: the standard deviation of the x colour channel (green-red variation) measured from all ROI pixels
- rnl_y_mean: the mean value of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_y_dev: the standard deviation of the y colour channel (yellow-blue variation) measured from all ROI pixels
- rnl_saturation_mean: the mean value of the saturation channel measured from all ROI pixels
- rnl_saturation_dev: the standard deviation of the saturation channel measured from all ROI pixels
- day: dummy variable set at day 30 to add a polygon representing the colour variation of the seaweeds to Figure 4
Code/software
Software
- R version 4.4.1 (2024-06-14 ucrt); Platform: x86_64-w64-mingw32/x64 (64-bit)
Packages
- afex v.1.3-1
- caret v.6.0-94
- colorspace v.2.1-1
- DHARMa v.0.4.7
- emmeans v.1.10.5
- lme4 v.1.1-35.5
- lmerTest v.3.1-3
- MASS v.7.3-61
- munsell v.0.5.1
- patchwork v.1.3.0
- performance v.0.12.3
- readxl v.1.4.3
- rstatix v.0.7.2
- tidyverse v.2.0.0
General information about the scripts: The scripts refer to the analyses and figure codes of the (i) colour variability and camouflage of wild chameleons prawns sampled from non-native seaweeds; (ii) choices between native and non-native seaweeds of green and red chameleon prawns; and (iii) colour change of green and red chameleon prawns against non-native seaweeds and native seaweed of contrasting coloration.
Scripts
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script_background_matching.R
Contains the analyses and the codes to create Figure 2 about the colour variation and camouflage of wild chameleon prawns sampled in the non-native seaweeds pink harpoon weed (Asparagospsis armata) and brown wireweed (Sargassum muticum).
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script_behavioural_choices.R
Contains the analyses and the codes to create Figure 3 about the behavioural choices of green and red chameleon prawns between native seaweeds with match or mismatchig coloration and the non-native seaweeds (pink harpoon weed and brown wireweed).
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script_colour_change.R
Contains the analyses and the codes to create Figure 4 of the colour change experiment of green and red chameleon prawns maintained for 30 days on colour-mismatching native seaweeds and non-native seaweeds (pink harpoon weed and brown wireweed).
Chameleon prawns (Hippolyte varians) and their seaweed hosts (native seaweeds: green sea lettuce Ulva lactuca and red dulse Palmaria palmata; non-native seaweeds: pink harpoon weed Asparagopsis armata and brown wireweed Sargassum muticum) were obtained from field samplings and used in different experiments in the laboratory. For both the field study and the colour change experiment, data for prawn colour and camouflage was obtained through digital images and quantified using methods of image analysis and visual modelling. Data for the behavioural-choice experiment was collected by assessing the choice of prawns for native versus non-native seaweeds in binomial trials.