DOI: 10.25338/b8td1f
title: Data accompanying: Population-specific patterns of toxin sequestration in monarch butterflies from around the world

description: Animals frequently defend themselves against predators and parasites using
 toxins obtained from their diets. Monarch butterflies are a preeminent
 example of toxin sequestration and gain protection from cardenolides in
 their milkweed host plants. Although sequestration behavior is
 well-studied in monarchs, relatively little research has studied genetic
 variation in sequestration ability. In this study, we use the monarch’s
 global range expansion to test hypotheses about how cardenolide
 sequestration has evolved over recent evolutionary history. First, using a
 reciprocal rearing experiment involving six monarch populations and six
 associated milkweed host species, we test for whether natural selection
 has increased cardenolide sequestration in monarch populations reared on
 their sympatric hosts. Second, we test for whether contemporary species
 interactions affect sequestration by measuring cardenolides in monarchs
 from Guam, an oceanic island where bird predators have been functionally
 absent for approximately 40 years. We find evidence for substantial
 genetic variation in sequestration ability, although no consistent pattern
 of enhanced sequestration in sympatric monarch/milkweed combinations. One
 monarch population (from Puerto Rico) shows strong support for cross-hosts
 tradeoffs in sequestration ability, with elevated sequestration from two
 tropical milkweed species (Asclepias curassavica, Gomphocarpus
 physocarpus) but greatly reduced sequestration from two temperate species
 (A. syriaca, A. speciosa). Monarchs from Guam show some evidence
 for reduced cardenolide sequestration in both a cross-island comparison of
 wild-caught butterflies as well as a population-level comparisons of
 greenhouse-reared butterflies. Our results suggest that processes involved
 in toxin sequestration are subject to natural selection and may evolve in
 response to contemporary changes in species interactions.
description: <strong>This manuscript contains data from two
 experiments:</strong> A common-garden
 experiment conducted in 2017 and 2018 that involved rearing monarch
 butterflies on various milkweed species in a greenhouse.
 Wild-caught butterflies from the Mariana Islands (Guam and Rota)
 collected in 2015. The primary data
 collected is chromatography data representing cardenolides present in
 milkweed leaf tissue and monarch butterfly wing tissue. For dataset 1,
 these data were generated by the lead author and processed into
 interpretable output (.csv files) using proprietary software (Chromeleon).
 For dataset 2, these data were generated and processed by Dr. Mark Hunter.
 All analyses were conducted using the resulting .csv files. We also
 included a number of raw data files (in .txt form) for the purpose of
 demonstration. <strong>The full repository
 contains the following files and directories:</strong>
 adult_data.csv : contains information for butterflies
 reared during experiment 1 chromatograms : directory
 containing .txt files for raw chromatogram readout from experiment
 1 concatenated_cardenolides.csv : full data matrix of
 cardenolide peaks across all leaf and wing tissue samples from experiment
 1 marianas_leaf_cardenolides.csv : data matrix of
 cardenolide peaks for milkweed leaf tissue collected in the field as part
 of experiment 2 marianas_wing_cardenolides.csv : data
 matrix of cardenolide peaks for monarch wing tissue collected in the field
 as part of experiment 2 tissue_mass.csv : contains
 dry mass of tissue used for cardenolide measurement 
 <strong>The scripts directory contains four R scripts that
 were used for all data analysis and figure/table generation. Those scripts
 are:</strong> 
 cardenolide_chromatograms.R : Script for plotting raw data from
 cardenolide readout. This script was used to produce Figure 2A and Figure
 S4. cardenolide_stats.R : Primary analysis script for
 statistics and most figures/tables. guam_cards.R :
 Script for processing data from Guam and Rota samples collected in 2015.
 This script was used to produce Figures 5B and 5C as well Figure
 S1. maps.R : Script for generating maps used in
 Figure 1A and Figure 5A 
description: All analyses were conducted in R version 4.0.3.