Data from: Exploring polymorphism in a palatable prey: Predation risk and frequency-dependence in relation to distinct levels of conspicuousness
Abstract
Camouflage and warning signals are different anti-predator strategies, which offer an excellent opportunity to study the evolutionary forces acting on prey appearance. Edible prey often escape detection via camouflage, which usually leads to apostatic selection favoring rare morphs. By contrast, defended prey often display conspicuous coloration acting as warning signals to predators, which usually leads to positive frequency-dependence and signal uniformity. However, when two morphs of the same species vary greatly in conspicuousness, the maintenance of both cryptic and conspicuous forms in profitable prey populations remains enigmatic. Using the white and melanic morphs of the invasive box tree moth (Cydalima perspectalis) presented at three different frequencies, we investigate a) the palatability of caterpillars and adult moths to birds, b) predation rates on the less conspicuous melanic morph, and c) the role of frequency-dependence in balancing morph frequencies. Our results show that caterpillars are distasteful for birds but not adult moths, which are fully palatable. We found that the less conspicuous, melanic morph, benefits from reduced predation due to its lower detectability. The more conspicuous, white morph, instead, is more predated and is best off when common, suggesting positive-frequency dependence. These results offer new insights into the evolution of color polymorphism and prey defenses in a polymorphic moth species. Further investigation is required to understand the role of different predation regimes on the maintenance of the polymorphism in this species, and test if additional selection pressures operate in natural populations.
README: Exploring polymorphism in a palatable prey: Predation risk and frequency-dependence in relation to distinct levels of conspicuousness
https://doi.org/10.5061/dryad.b8gtht7kp
This dataset contains raw data and code for analyses concerning the aforementioned article.
Description of the data and file structure
Directory structure
|− Detection.Rmd
|- Palatability.Rmd
|- Permutaion_analysis.Rmd
|- Spectra.Rmd
|- Vision_model.Rmd
|- data/
|- |- Bird_info.csv
|- |- detection.csv
|- |- palatability_adults_boxtreemoth.csv
|- |- palatability_clean.csv
|- |- palatability_caterpillars.csv
|- |- spectra/
|- |- |- box_tree/
|- |- |- |- (several files)
|- |- |- camouflage_net/
|- |- |- |- (several files)
|- |- |- moths/
|- |- |- |- (several files)
Description of each file
data/
Bird_info.csv: contains the individual information about birds, such as age, sex and ring number.
- IDBird: unique identification number given to each bird tested in the experiment
- Ring_Nb: unique ring number given to the bird for monitoring purposes by the Finnish Museum of Natural History
- Sexe: sex of the bird
- Age: age of the bird
- Wing_length: wing length in millimeters (mm)
- Weight_In: weight at catching date in grams (g)
- Weight_Out: weight at releasing date in grams (g)
- Catch_Date: day when the bird was catched in the format dd/mm/yy
- Release_Date: day when the bird was released in the format dd/mm/yy
- Adult_Palatability_Date: date when the bird was tested in adult palatability experiment in the format dd/mm/yy
- Overnight_Training_Date: date when the bird was placed overnight in the experimental room
- Adult_Detectability_Date: date when the bird was tested in detection experiment in the format dd/mm/yy
- IDTreatment: treatment ID (i.e. 50B50N, 20B80N or 80B20N)
- IDTrial: Trial ID (i.e. 1st, 2nd, 3rd etc. trial of the same treatment)
- Caterpillar_Date: date when the bird was tested in caterpillar palatability experiment in the format dd/mm/yy
detection.csv: contains the data for the detection experiment. For knowing how the time variables are defined, please refer to the paper. Each line represents a moth that was placed in the experimental ground, hence each trial has 30 lines.
- IDBird: unique identification number given to each bird tested in the experiment
- IDTreatment: ureatment ID (i.e. 50B50N, 20B80N or 80B20N)
- IDTrial: trial ID (i.e. 1st, 2nd, 3rd etc. trial of the same treatment)
- StartTime: time when when the experiment started expressed in hh:mm:ss
- EndTime: time when when the experiment ended expressed in hh:mm:ss
- Duration: duration of the experiment in minutes (min)
- FoodDeprived: interval in which the bird was food deprived in minutes (min)
- GridPosition: position of the moth in the experimental grid (e.g. A7, B3, etc.)
- ButterflyColor: colour form of the moth (B = white form, N = melanic form)
- Found: binary, indicates whether the moth was found by the bird during the trial (either 0 = not found or 1 = found)
- Order: catching order, the first moth found is marked as 1, etc.
- RestPerchTime: time spent by the bird on the perch or resting (i.e. not actively searching for moths on the ground) in seconds
- SearchTime: time spent by the bird actively searching for moths in seconds
palatability_adults_boxtreemoth.csv: contains the data for the palatability experiments ran using adult moths.
- IDBird: unique identification number given to each bird tested in the experiment
- Day: day when the experiment was performed in the format dd/mm/yy
- StartTime: time of the day when the experiment began in the format hh:mm
- EndTime: time of the day when the experiment ended in the format hh:mm
- Duration: duration of the experiments in minutes (min)
- FoodDeprived: interval in which the bird was food deprived in minutes (min)
- Prey: prey type (P = peanut, B = white moth, N = melanic moth)
- Order: prey order according to how they were given to the bird
- PerchTime: time spent before coming onto the perch of the experimental cage, hence before seeing the prey presented, in seconds (s)
- EatTime: time spent on the perch, before catching the prey in seconds (s)
- Behavior: categorical, indicates if the prey was eaten or refused or any intermediate situation (EAT = prey was eaten, REF = prey was refused, CATCH = prey was catched but not eaten, HALF = prey was partially eaten)
- HandlingTime: time spent eating the prey. Since it is often very short, this variable was seldom measured
- Peanut_Order: categorical, indicates whether the peanut was presented at the beginning (BEG) to habituate the bird to the experimental system, at the middle (MID) or at the end (END) to ensure that the bird was still hungry.
palatability_clean.csv: contains the data obtained from cleaning the previous dataset (palatability_adults_boxtreemoth.csv), i.e. removing manually the individuals for which no MID or END peanut was available. It includes only the columns IDBird, Prey, Order, EatTime.
palatability_caterpillars.csv: contains the data for the palatability experiments ran using box tree moth caterpillars.
- IDBird: unique identification number given to each bird tested in the experiment
- Day: day when the experiment was performed in the format dd/mm/yy
- StartTime: time of the day when the experiment began in the format hh:mm
- EndTime: time of the day when the experiment ended in the format hh:mm
- Duration: duration of the experiments in minutes (min)
- FoodDeprived: interval in which the bird was food deprived in minutes (min)
- Prey: prey type (P = peanut, B = white moth, N = melanic moth)
- Peanut_Order: categorical, indicates whether the peanut was presented at the beginning (BEG) to habituate the bird to the experimental system, at the middle (MID) or at the end (END) to ensure that the bird was still hungry.
- Order: prey order according to how they were given to the bird
- PerchTime: time spent before coming onto the perch of the experimental cage, hence before seeing the prey presented, in seconds (s)
- EatTime: time spent on the perch, before catching the prey in seconds (s)
- Behavior: categorical, indicates if the prey was eaten or refused or any intermediate situation (EAT = prey was eaten, REF = prey was refused, CATCH = prey was catched but not eaten, HALF = prey was partially eaten)
data/spectra
- box_tree/ - contains the files with measurements for box tree leaves. Each measurement has three files (.ttt, .TCM, .TRM) that need to be stored together. Each triplet corresponds to a specific leaf and a specific anatomical part. Please, see the relevant R markdown script for a detailed description. The files are in ttt format and can be read with pavo2 package using the provided script. The files dark0.dat and ref0.dat are not necessary for the analysis, but may be used to know what were the spectral data for the reference used for white and dark.
- camouflage_net/ - contains the files with measurements for the background used in the detection experiment. Each file corresponds to a different part of the background. Please, see the relevant R markdown script for a detailed description. The files are in txt format and can be read with pavo2 package using the provided script.
- moths/ - contains files with measurements for the adult moths mesured. Each measurement has four files (.dx, .ttt, .TCM, .TRM) that need to be stored together. Each group corresponds to a different individual or a different portion of the wing. Please, see the R markdown script for a detailed description or to the file mesures_spectro_adults.csv. The files can be read with pavo2 package using the provided script. The files dark0.dat and ref0.dat are not necessary for the analysis, but may be used to know what were the spectral data for the reference used for white and dark.
Code/Software
The code is given in R markdown files. The file paths are already set to link directly to the relevant files.
- Detection.Rmd: this script has to be used for analyzing the predation experiment, but don't contain the permutation analysis.
- Permutaion_analysis.Rmd: this script contains the code to run permutation analysis used to analyse the data from the predation experiment.
- Palatability.Rmd: this script has to be used to analyze the data from the palatibility experiments on adults and caterpillars.
- Spectra.Rmd: this script has to be used to analyze the spectra.
- Vision_model.Rmd: this script has to be used to perform vision modeling