DOI: 10.5061/dryad.k3j9kd5mm
title: Data from: Evolutionary constraints in host shifts: limited adaptation of <em>Plutella xylostella</em> to cardenolide-defended <em>Erysimum cheiranthoides</em>

description: Coevolutionary arms races between plants and insects, in which gains of
 novel plant defences select for counter-adaptations in herbivores, are key
 drivers of biodiversity. In the Brassicaceae genus Erysimum, the evolution
 of cardenolide toxins represents a recent innovation that effectively
 deters many Brassicaceae herbivores. Nonetheless, some herbivores continue
 to attack Erysimum, potentially representing early adapters of a novel
 toxic host on the path toward specialization. Here, we investigated the
 interaction between the diamondback moth (DBM, Plutella xylostella) and
 the cardenolide-producing plant E. cheiranthoides, by first assessing
 standing variation in DBM performance on Erysimum, and then experimentally
 evolving DBM populations for improved performance over 24 generations.
 Although wild DBM populations varied in their traits, larvae consistently
 fed less on Erysimum leaves in choice assays, and when constrained to
 Erysimum, they exhibited reduced growth rate, survival, and lower adult
 size compared to individuals feeding on broccoli controls. Growth assays
 in which a purified cardenolide compound was added to broccoli leaves
 demonstrated a partial susceptibility of DBM to this toxin. However,
 experimental evolution failed to enhance performance on Erysimum, and
 instead, phenotypes of evolved lines converged on a pre-existing, highly
 plastic phenotype also observed among wild DBM populations. This phenotype
 was characterized by rapid development and high weight gain on control
 plants, but slow development and low weight gain on Erysimum. Although DBM
 did not evolve improved performance on Erysimum over 24 generations, our
 results demonstrate that existing genetic variation and phenotypic
 plasticity are sufficient to support long-term development on this toxic
 host, thereby fulfilling a key prerequisite for the eventual evolution of
 specialized adaptations.
description: # Evolutionary constraints in host shifts: limited adaptation of *Plutella
 xylostella* to cardenolide-defended *Erysimum cheiranthoides* Dataset DOI:
 [10.5061/dryad.k3j9kd5mm](10.5061/dryad.k3j9kd5mm) ## Description of the
 data and file structure ### Description of the data and file structure Raw
 data provided as .csv files and complete R code used in the analysis of
 the data and visualization of results. ### Files and variables #### File:
 Rscript_full_v8.html Complete R code to analyze herbivore choice and
 herbivore performance of diamondback moth (DBM) populations in response to
 different host plants, to analyze changes in adult mass and adult
 ecolosion during experimental evolution, and to analyze choice and
 performance of evolving DBM selection lines at different points of
 experimental evolution. #### File: DBM_bayesian_emergence_model.R R code
 for hierarchical Bayesian model to predict daily emergence time from
 collection interval counts. #### File: P20_AA.csv Data from association
 (choice) assays using L1 larvae from 20 wild DBM populations
 (**Experiment** = P20-AA). DBM **Populations** had been reared in
 experimental **Cohorts** (A-D) for a variable number of **Generations**
 since collection in the wild. Assays were performed in two **Repeats**
 (1-2) separated by 1-4 generations, for a total of 14 replicates per
 population (**Assay.Replicate**). Each replicate consisted of one Petri
 dish (**Plate.ID**) which was set up (**Start.Date**, **Start.Time**) with
 three discs of broccoli and *Erysimum* leaves each. At the end of the
 assay (**End.Date**, **End.Time**) approximately 24 hours later
 (**Assay.Time**), larvae feeding on *Erysimum* leaf discs
 (**Larvae.E1-E3**) and broccoli (**Larvae.B1-B3**) were counted, and
 summed by plant species (**Larvae.Ery**, **Larvae.Bro**) and Petri dish
 (**Larvae.Total**) #### File: P20_GR.csv Data from larval growth rate
 assays using L2 larvae from 20 wild DBM populations (**Experiment** =
 P20-GR). DBM **Populations** had been reared in experimental **Cohorts**
 (A-D) for a variable number of **Generations** since collection in the
 wild. Assays were performed in four 12-well plates per population
 (**Assay.Plate**, **Plate.ID**), with individual larvae (**Larval.ID**)
 assigned to the wells in each plate (**Position**). Wells contained leaf
 discs of three **Treatments** (Bro = broccoli leaf; Bro-Dig = broccoli
 leaf with added digitoxin; Ery = *Erysimum* leaf). Larvae were weighed
 (**Weight** [mg]) at setup (**Timepoint** = 0 [h], **Date**, **Time**),
 after 24 hours (**Timepoint** = 24 [h]) with provision of fresh leaf discs
 according to treatment, and again after 48 hours (**Timepoint** = 48 [h]).
 #### File: P20_LH.csv Data from life-history assay following the
 development of L2 larvae to adult eclosion for 20 wild DBM populations
 (**Experiment** = P20-LH). DBM **Populations** had been reared in
 experimental **Cohorts** (A-D) for a variable number of **Generations**
 since collection in the wild. Assays were set up whole broccoli
 (**Assay.Plant** = Bro) or *Erysimum* plants (**Assay.Plant**) using
 custom-made fabric mesh 'sleeves' (**Sleeve**, **Sleeve.ID**).
 At setup (**Start.Date**), 20 L2 larvae were added to each sleeve, which
 were recovered as pupae (**Larval.ID**). Only successfully pupated
 (**Pupation** = 1) and eclosed (**Eclosion** = 1) were recorded for this
 dataset. Date of eclosion (**Eclosion.Date**) was recorded to calculate
 development time in days since setup (**Development.Time** [days]).
 Eclosed adults were frozen, sexed (**Sex** =M/F), and weighed after drying
 (**Adult.Mass** [mg]). #### File: S12_AdultMass.csv Data from continuous
 collection of newly eclosed adults emerging from the selection experiment.
 Replicate **Populations** were maintained in experimental **Cohorts**
 (A-D) under two **Selection** regimes (Sel-Bro: developing on broccoli;
 Sel-Ery = developing on *Erysimum*). In each generation
 (**Generation.Sel**, **Generation.Sel.num**), a batch of approximately 30
 adults was collected (**Collection.Date**), followed by sexing (**Sex** =
 M/F), and weighing of 10 dried male and 10 female moths (**Replicate**,
 **Adult.Mass** [mg]). #### File: S12_AdultEmergence.csv Data from
 continuous rearing of DBM in the selection experiments. Replicate
 **Populations** were maintained under two **Selection** regimes (Sel-Bro:
 developing on broccoli; Sel-Ery = developing on *Erysimum*). In each
 generation (**Generation.Sel**), populations were set up by adding DBM
 eggs to fresh food plants in a growth chamber (**Setup.Date**). Beginning
 approximately 2.5 weeks later, emerging were collected repeatedly
 (**Collection.Date**). At each collection, total number of adults was
 recorded (**Adults.Collected**), and subsets were kept for establishing
 the next generation (**Adults.Kept**), frozen for weight determination
 (**Adults.Frozen**), or discarded to avoid overcrowding
 (**Adults.Discarded**). Each collection is numbered sequentially
 (**Collection.Interval**) and by time since population set up
 (**Development.Time** [days]). #### File:
 S12_AdultEmergence_PredDailyEmerg.csv Model predictions of daily adult
 emergence from a hierarchical Bayesian model using adult counts from
 collection intervals recorded in S12_AdultEmergence.csv. Model output is
 provided due to long model runtime (~8-10 hours). Replicate
 **Populations** were maintained under two **Selection** regimes (Sel-Bro:
 developing on broccoli; Sel-Ery = developing on *Erysimum*). For each
 generation (**Generation.Sel**), we estimated daily emergence for each day
 since population set up (**Development.Time** [days]), starting two days
 before the first adult collection. Mean predicted numbers of daily
 emerging adults with 95% confidence intervals (**Emergence.Mean,
 Emergence.CI.lower, Emergence.CI.upper**) correspond to total collected
 adults in that collection interval (**Collection.Interval**). #### File:
 S12_AA.csv Data from association (choice) assays using L1 larvae from 12
 DBM selection lines (**Experiment** = S12-AA). Selection lines
 (**Population)** had been reared in experimental **Cohorts** (A-D) under
 two **Selection** regimes (Sel-Bro: developing on broccoli; Sel-Ery =
 developing on *Erysimum*) and were assayed at specific generations of the
 selection experiment (**Generation.Sel**). Assays were performed in Petri
 dishes (**Plate.ID**) with 6 replicates (**Assay.Replicate**) per
 selection line. Each dish was set up (**Start.Date**, **Start.Time**) with
 three discs of broccoli and *Erysimum* leaves each. At the end of the
 assay (**End.Date**, **End.Time**) approximately 24 hours later
 (**Assay.Time**), larvae feeding on *Erysimum* leaf discs
 (**Larvae.E1-E3**) and broccoli (**Larvae.B1-B3**) were counted, and
 summed by plant species (**Larvae.Ery**, **Larvae.Bro**) and petri dish
 (**Larvae.Total**) #### File: S12_GR.csv Data from larval growth rate
 assays using L2 larvae from 12 DBM selection lines (**Experiment** =
 S12-GR). Selection lines (**Population)** had been reared in experimental
 **Cohorts** (A-D) under two **Selection** regimes (Sel-Bro: developing on
 broccoli; Sel-Ery = developing on *Erysimum*) and were assayed at specific
 generations of the selection experiment (**Generation.Sel**,
 **Generation.Sel.num**). Assays were performed in three 12-well plates per
 population (**Assay.Plate**, **Plate.ID**), with individual larvae
 (**Larval.ID**) assigned to the wells in each plate (**Position**). Wells
 contained leaf discs of three **Treatments** (Bro = broccoli leaf; Bro-Dig
 = broccoli leaf with added digitoxin; Ery = *Erysimum* leaf). Larvae were
 weighed (**Weight** [mg]) at setup (**Timepoint** = 0 [h], **Date**,
 **Time**), after 24 hours (**Timepoint** = 24 [h]) with provision of fresh
 leaf discs according to treatment, and again after 48 hours (**Timepoint**
 = 48 [h]). #### File: S12_LH.csv Data from life-history assay following
 the development of L2 larvae to adult eclosion for 12 DBM selection lines
 (**Experiment** = S12-LH). Selection lines (**Population)** had been
 reared in experimental **Cohorts** (A-D) under two **Selection** regimes
 (Sel-Bro: developing on broccoli; Sel-Ery = developing on *Erysimum*) and
 were assayed at specific generations of the selection experiment
 (**Generation.Sel**, **Generation.Sel.num**). Assays were set up whole
 broccoli (**Assay.Plant** = Bro) or *Erysimum* plants (**Assay.Plant**)
 using custom-made fabric mesh 'sleeves' (**Sleeve**,
 **Sleeve.ID**). At setup (**Start.Date**), 20 L2 larvae were added to each
 sleeve, which were recovered as pupae (**Larval.ID**). Only successfully
 pupated (**Pupation** = 1) and eclosed (**Eclosion** = 1) were recorded
 for this dataset. Date of eclosion (**Eclosion.Date**) was recorded to
 calculate development time in days since setup (**Development.Time**
 [days]). Eclosed adults were frozen, sexed (**Sex** =M/F), and weighed
 after drying (**Adult.Mass** [mg]). ## Code/software ### Code/Software R
 script was run in version 4.5.0