DOI: 10.5061/dryad.fbg79cp74
title: Dietary constraints and costs of melanin pigmentation plasticity

description: Understanding the evolution of adaptive plasticity requires considering
 the costs of producing a plastic trait. We test the hypothesis that diet
 can act as a constraint on melanin pigmentation and lead to costly
 resource allocation trade-offs in Hyles lineata, the white-lined sphinx
 moth. In a diet manipulation experiment, we found that two aspects of
 melanin pigmentation, percent melanic area and darkness, are relatively
 robust in the face of diet variation in environments where they are
 prioritized. Next, we tested whether larval melanin pigmentation is
 involved in resource allocation trade-offs with traits sharing the same
 dietary precursors: larval immune response, adult flight muscle mass, and
 adult wing pigmentation. Larval pigmentation trades off with both immunity
 and adult pigmentation. Contrary to many patterns reported in the
 literature, these trade-offs existed on the high resource diet, but not
 the low resource diet, indicating that certain traits may have a minimum
 threshold of expression. Larvae can plastically increase melanin
 pigmentation in contexts where melanin benefits outweigh costs, but
 otherwise reduce melanin pigmentation so that limited dietary precursors
 can be allocated to immunity and adult pigmentation. These
 context-specific costs and benefits of melanin can help explain the
 adaptive value of melanin plasticity in this species.
description: # Dietary constraints and costs of melanin pigmentation plasticity Dataset
 DOI: [10.5061/dryad.fbg79cp74](10.5061/dryad.fbg79cp74) ## Description of
 the data and file structure **Experiment 1**- The first experiment
 contains data from dietdata.csv (primary data set) as well as
 feedingdata.csv (subset of individuals used for feeding trials) and
 extraction_data.csv (subset of individuals used for melanin extraction). 
 **diet_data.csv:** ID- Unique larval identifier diet_treatment- One of the
 5 diet treatments (see text for details) photo_mass- Mass (grams) at the
 time the photo was taken devo_total_time- Total development time from egg
 to end of 5th instar devo_5th_length- Time (in days) of the 5th instar
 blocking_mass- Mass (grams) after gut purge/ before pupation
 melanin_percent - Proportion of melanin pixels of total pixels darkness-
 Calculated by subtracting the average gray value under the threshold from
 35 (see text for details) **feeding_data.csv:** ID- Unique larval
 identifier diet_treatment- One of the 5 diet treatments (see text for
 details) fourth_mass- Mass (grams) of larva at start of feeding trial, 4th
 instar trials fourth_food_change- Change in mass (grams) of artificial
 food block over 24-hr feeding trial, 4th instar trials fifth_mass- Mass
 (grams) of larva at start of feeding trial, 5th instar trials
 fifth_food_change- Change in mass (grams) of artificial food block over
 24-hr feeding trial, 5th instar trials *Note that the same individuals
 were not necessarily used in both instars, so for some individuals, there
 are some blank cells.  **extraction_data.csv:** ID- Unique larval
 identifier diet_treatment- One of the 2 diet treatments (only high vs low
 used for extractions) full_mass- Mass (grams) of shed cuticle
 extraction_run- Extraction block subsample_mass- Mass (grams) of subsample
 used from crushed cuticle concentration- Concentration (ug/ml) of melanin
 from spectrophotometer  total_extracted- Total amount of melanin extracted
 (ug) **Experiment 2-** This second experiment contains all the datasets
 for looking at melanin trade-offs including tradeoff_data.csv (primary
 dataset with all individuals), immunedata.csv (for subset of individuals
 that underwent immune assay), KOHdata.csv (for subset of individuals that
 underwent muscle assay), and wing_data.csv (for subset of individuals with
 wing pigmentation data). All of this data is collated in R scripts. 
 **tradeoff_data.csv:** Larval_ID- Unique larval identifier Sex- M (male),
 F (female), or left blank because the individual did not make it to
 adulthood to be sexed Family- One of 6 families in the study
 Full_Treatment- Combination of photoperiod and diet treatments
 Photo_Treatment- Either Long or Short (photoperiod) Photo_Binary-
 Photoperiod treatment as binary; 1=Long 0=Short Diet_Treatment- Either Low
 or High (tyrosine content) Diet_Binary- Diet treatment as binary; 1=High,
 0=Low Devo_5th- Length (days) of 5th instar Devo_Total- Length of 5th
 instar and pupal stage Percent_R/G/B- Proportion melanic pixels from the
 red, blue, or green channels of the image Notes- Experimental notes,
 especially on deaths/losses *Note that only individuals that completed the
 larval stage were able to be sexed. Individuals used for the immune assay
 did not complete the larval stage and thus do not have data for Devo_5th
 or Devo_Total. **immune_data.csv:** Larval_ID- Unique larval identifier
 Mass- Mass (grams) before immune assay Food_Change- Change in mass (grams)
 of artificial food block during the immune assay, amount eaten by the
 larva Consumption_per_mass- Food_Change/ Mass Total_Melanin- Total melanin
 (ug) extracted from wire Wire_Length- Size of wire (mm) Concentration-
 Concentration of melanin (total/ wire) *Note that for some individuals,
 food consumption was not measured, so there are blank values for
 Food_Change and Consumption_per_mass  **KOH_data.csv:** Larval_ID- Unique
 larval identifier Set- Assay block full_mass- Mass (grams) of adult moth
 before_thorax- Mass (grams) of just the thorax (with scales removed)
 before KOH treatment and drying after_thoax- Mass (grams) of thorax after
 KOH treatment and drying muscle_mass- before_thorax - after_thorax
 muscle_percent- muscle_mass/full_mass Notes- relevant experimental notes
 exclude- whether or not to exclude, based on notes **wing_data.csv:**
 Larval_ID- Unique larval identifier fore_gray_R/G/B- gray value of the
 forewing in the red/green/blue channels fore_gray- average gray value on
 forewing across all channels fore_darkness- fore_gray subtracted from 255
 (max possible gray value) hind_gray_R/G/B- gray value of the hindwing in
 the red/green/blue channels hind_gray- average gray value on hindwing
 across all channels (under threshold) hind_darkness- hind_gray subtracted
 from 19 (max possible gray value based on threshold) hind_percent_R/G/B-
 proportion melanic pixels under threshold in red/green/blue channels on
 hindwing hind_percent- average proportion over all three channels on
 hindwing notes- notes on any samples or photos that will explain why any
 data might be missing in other cells