DOI: 10.5061/dryad.n8pk0p32k
title: Data from: A range-expanding butterfly is susceptible to cold and long winters but shows no signs of local adaptation to winter conditions

description: Numerous species shift or expand their ranges polewards in response to
 climate change. Even when expanding species follow their climatic niches,
 expanding range margin populations are likely to face unfamiliar
 environmental conditions and thus natural selection for local adaptation.
 The wall brown butterfly (Lasiommata megera) has expanded northwards in
 Sweden in the years 2000–2020, most likely as a result of climate change,
 and has previously been shown to have evolved local adaptations to
 northern daylength conditions. This evolution has occurred despite
 hypothesised genetic constraints to adaptation at range margins. We
 studied local adaptation to winter conditions in four of the
 previously-studied L. megera populations, using a common garden
 laboratory experiment with a warm and short, an intermediate, and a cold
 and long winter treatment. We compared the winter and post-winter survival
 of caterpillars from two southern core range and two northern range margin
 populations in Sweden. During the experiment, we measured metabolic rates
 of a subset of diapausing caterpillars to test whether populations differ
 in metabolic suppression during diapause. Further, we measured
 supercooling points, which reflect lower lethal temperature in L.
 megera, of the same subset of caterpillars. We also compared supercooling
 points between L. megera and three closely related species with more
 northern distributions. Few individuals survived the coldest treatment all
 the way to successful adult emergence, so L. megera seems
 susceptible to cold winters. Individuals of northern descent did not
 survive cold winters any better than individuals from southern
 populations. Similarly, there were no signs of local adaptation in
 metabolic rates or supercooling points. The comparison among species did
 not reveal any clear relationship between geographical distribution and
 supercooling point. Although northern winters probably exert strong
 selection on L. megera, we provide comprehensive evidence for the
 lack of local adaptation to winter conditions. This contrasts with the
 previous finding of quickly-evolved local adaptation in diapause timing,
 highlighting the need to consider how traits associated with different
 seasons differ in how they may evolve and facilitate climate
 change-induced range expansions.
description: # Data from: A range-expanding butterfly is susceptible to cold and long
 winters but shows no signs of local adaptation to winter conditions
 [https://doi.org/10.5061/dryad.n8pk0p32k](https://doi.org/10.5061/dryad.n8pk0p32k) This file contains information about the data files used in Ittonen et al.: A range-expanding butterfly is susceptible to cold and long winters but shows no signs of local adaptation to winter conditions. Descriptions of the data and explations for each column in the data tables are given under each file name below. ## Winter survival data (the main experiment) ### winter\_survival.txt Binary survival data from the main experiment. **id:** individual identifier for each caterpillar **sort1 and sort2:** columns for sorting the data after id **treatment:** The winter treatment (warm, intermediate, or cold) that each caterpillar was kept in **family:** identifier for each mother of the caterpillars in the experiment **population:** the location where each caterpillar’s parents were caught **variable:** the life stage for assessing survival: ‘survived\_winter’ (whether caterpillars were alive at the end of the winter treatments), ‘pupated’ (whether the caterpillar pupated), or ‘adult\_ok’ (whether the pupa eclosed successfully) **value:** A true (1) or false (0) value for ‘variable’. For example, a row with variable=adult\_ok and value=1 means that the individual developed all the way into a seemingly healthy adult. **start\_weight:** individual body mass (in mg) the day of starting the pre-winter treatment ### survival\_ci.txt 95 % confidence intervals for Fig. 4a. **population:** The population **treatment:** The winter treatment **stage:** The life stage for assessing survival: 'surv' (whether the caterpillar was alive after the winter treatment), ‘pupated’ (whether the caterpillar pupated), or ‘adult\_ok’ (whether the pupa eclosed successfully) **ci\_low:** the lower confidence bound **ci\_high:** the higher confidence bound ### direct\_development.txt Data of pupation and adult emergence success under the non-diapause development experiment **id:** individual identifier for each caterpillar **treatment:** ‘direct’ for all individuals, only used for plotting purposes **family:** identifier for each mother of the caterpillars in the experiment **population:** the location where each caterpillar’s parents were caught **start\_weight:** mass (in mg) on the day of starting the direct development treatment for each individual **value:** A true (1) or false (0) value for ‘variable’. **variable:** pupated (whether the caterpillar pupated) or adult\_ok (whether the pupa eclosed successfully). For example, a row with variable=adult\_ok and value=1 means that the individual developed all the way into a seemingly healthy adult. ### direct\_ci.txt 95 % confidence intervals for eclosion success under non-diapause development (used in Fig. 4b). **population:** The population **treatment:** ‘direct’ for all rows, only used for plotting purposes **variable:** pupated (whether the caterpillar pupated successfully) and adult\_ok (whether the pupa eclosed successfully) **ci\_low:** the lower confidence bound **ci\_high:** the higher confidence bound **proportion:** the actual proportion that pupated or emerged successfully ## Respirometry data ### respirometry\_main.txt Respirometry data from measurements done during the main experiment on a separate set of individuals. Excluding Vejbystrand in the intermediate treatment. **id:** individual identifier for each caterpillar **family:** identifier for each mother of the caterpillars **population:** the location where each caterpillar’s parents were caught **treatment:** The treatment (pre (pre-winter), warm, intermediate, or cold) that each caterpillar was kept in **startweight:** body mass (in mg) on the day of starting the pre-winter treatment for each individual **endweight:** body mass (in mg) on the day of the respirometry **syringe\_time:** the time (in hours) that each caterpillar spent in the treatments after their syringes were filled **co2:** the amount of CO2 pushed from the syringes in ml per hour and gram of body mass (variable ‘endweight’). ### respirometry\_supplement.txt (data for Fig. S1) Respirometry data from measurements done during the main experiment on a separate set of individuals. Including Vejbystrand in the intermediate treatment. **id:** individual identifier for each caterpillar **family:** identifier for each mother of the caterpillars **population:** the location where each caterpillar’s parents were caught **treatment:** The treatment (pre (=pre-winter), warm, intermediate, or cold) that each caterpillar was kept in **startweight:** body mass (in mg) on the day of starting the pre-winter treatment for each individual **endweight:** body mass (in mg) on the day of the respirometry **syringe\_time:** the time (in hours) that each caterpillar spent in the treatments after their syringes were filled **co2:** the amount of CO2 pushed from the syringes in ml per hour and gram of body mass (variable ‘endweight’). ### Lmeg\_MR\_for\_model Data for assessing metabolic rate-temperature relationships and producing Fig. 5b. **id:** individual identifier for each caterpillar **pop:** the location where each caterpillar’s parents were caught (H=Hässleholm, K=Katrineholm) **vco2:** the amount of respired carbon dioxide in microliters per hour **temp:** The temperature in which the caterpillar was kept (°C) **mass:** caterpillar body mass in mg **vo2:** the amount of respired oxygen in microlitres per hour ### main\_exp\_durations\_masses.csv File with caterpillar individual masses and the durations of the treatments. Used for Fig. 5c in the article. **id:** individual identifier for each caterpillar **treatment:** The winter treatment ( warm, intermediate, or cold) that each caterpillar was kept in **family:** identifier for each mother of the caterpillars **population:** the location where each caterpillar’s parents were caught **start\_weight:** body mass (in mg) on the day of starting the pre-winter treatment for each individual **end\_weight:** body mass (in mg) on the day of the respirometry **duration\_days:** The number of days that the caterpillar was in its respective treatment ## Supercooling point data ### scp.txt Data for supercooling point measurements with *Lasiommata megera* caterpillars that were kept in main experiment treatments. **id:** individual identifier for each caterpillar **family:** identifier for each mother of the caterpillars **population:** the location where each caterpillar’s parents were caught **treatment:** the winter treatment that each caterpillar was kept in **startweight:** mass (in mg) on the day of starting the pre-winter treatment for each individual **endweight:** mass (in mg) on the day of the supercooling point measurements **weight\_loss:** the difference between startweight and endweight **scp:** the measured supercooling point in °C ### scp\_comparison.txt Data for the supercooling point comparison among species. **species:** Abbreviated species name (Paeg = *Pararge aegeria,* Lpet = *Lasiommata petropolitana*, Lmae = *Lasiommata maera*, Lmeg  *Lasiommata megera*. **batch:** Which batch (each species was divided into two batches, making eight batches [coded a–h] in total) the measurement was made in. **scp:** the measured supercooling point in °C **id:** identifier for each caterpillar (different naming system for each species) **family:** identifiers for the mother of each caterpillar **weight:** the individual’s mass (in mg) on the day of measuring the supercooling points ## Appendix 1 ### chill\_susceptibility.txt Data from the chill susceptibility tests. **id:** within-batch individual identifier for each caterpillar **date:** the dates (in the winter 2021–2022) when the assays were made **channel:** channel for recording the temperatures. **froze:** whether a freezing exotherm was present (1) or absent (0) **weight:** individual body mass (in mg) on the day of starting the assay **alive:** whether the caterpillar survived (1) or died (0) ### freeze\_tolerance.txt Data from freeze tolerance tests. **dates:** The dates (in March 2022; e.g. 10–11/3 = 10–11 March 2022) when the assays were made. **caterpillar\_control:** whether the row represents a measurement with a caterpillar; a control with just ice, water and paper (control); or a control with only a thermocouple in empty tubes (empty\_control). **channel:** channel for recording the temperatures. Can be used to connect the columns in the raw data files described below to our scoring in this file. **alive:** whether the caterpillar was dead (0) or alive (1) after the treatment. NA for controls, which did not have caterpillars. **type\_of\_curve:** our classifcation of the temperature curve, that is, whether each caterpillar was likely to have frozen or not. A and B indicate freezing, C indicates not freezing, and D could mean both; see Figure A1 in Appendix 1. Raw data for plotting these curves are in the files freeze\_tolerance\_10\_11\_March.csv, freeze\_tolerance\_15\_16\_March.csv, freeze\_tolerance\_17\_18\_March.csv, and freeze\_tolerance\_22\_23\_March.csv. ### freeze\_tolerance\_10\_11\_March.csv, freeze\_tolerance\_15\_16\_March.csv, freeze\_tolerance\_17\_18\_March.csv, and freeze\_tolerance\_22\_23\_March.csv Raw data files from freeze tolerance assays. Can be used to plot the curves that we interpreted for freeze\_tolerance.csv. The first column in each file is the time (in seconds) since we started measuring temperatures, and each additional column represents one channel with or without a caterpillar. See freeze\_tolerance.csv for whether these channels represent a caterpillar or control trial, whether each caterpillar died, and how we interpreted the respective temperature curves. ## Code/Software The file R\_script.R contains the annotated scripts used for the analyses in our article.