Parental thermal environment affects offspring resilience to winter and spring weather anomalies
Data files
Jun 30, 2026 version files 73.60 KB
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egg_mass_area.csv
2.06 KB
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maternal_id.csv
3.22 KB
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offspring_spring_survival.csv
5.60 KB
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offspring_winter_survival.csv
3.39 KB
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offspring.csv
7.81 KB
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parents.csv
42.25 KB
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README.md
9.27 KB
Abstract
Recent increases in the frequency and intensity of thermal anomalies can result in recurrent stressful weather events. Among annual insects, this phenomenon may expose parents and offspring to different, but subsequent weather anomalies (e.g. summer heatwaves and late spring frosts). Parental stress can alter offspring physiology and performance, potentially affecting their tolerance of environmental variation. We performed a laboratory experiment using Percival incubators to investigate the transgenerational effects of thermal anomalies on a univoltine wetland butterfly (Baltimore Checkerspot, Euphydryas phaeton). We induced parental thermal stress by exposing pupae to a constant temperature, ranging from stressfully cold to stressfully hot (10 °C, 26 °C, 28 °C, 32 °C), for three days. Offspring were then subjected to either winter heatwaves or spring thermal anomalies. We found that in the parental generation, pupal exposure to heat stress (32 °C) reduced adult longevity by 46 %, while exposure to 28 °C maximized female reproductive output. Parental exposure to thermal stress did not affect offspring larval mass at the onset of diapause, but it did reduce offspring survival during winter and spring. Under winter heatwaves, survival was significantly higher among offspring of parents exposed to 26 °C than those exposed to 10 °C. Parental thermal stress was associated with decreased offspring survivorship in spring under control conditions and after a late frost. We observed anticipatory parental effects, as offspring of heat-stressed parents had increased survival under winter heatwaves, and negative transgenerational effects, as offspring of both heat and cold-stressed parents exhibited lower spring survivorship. We show a mechanism of how altered weather patterns can result in butterfly declines, highlighting the challenges that warming temperatures pose for insects.
Dataset DOI: 10.5061/dryad.vq83bk47v
Description of the data and file structure
We investigated the transgenerational effects of thermal anomalies on Baltimore Checkerspots (Euphydryas phaeton phaeton). We exposed the parental generation to thermal stress by assigning pupae to each of four constant temperature treatments: 10 °C, 26 °C, 28 °C, or 32 °C, for three days. Individuals that successfully emerged were allowed to mate within treatments and laid eggs. Offspring were then subjected to either winter heatwaves or spring thermal anomalies.
This data set includes: a) data on the responses to thermal treatments of the parental generation, including performance and reproductive output; b) survivorship data for offspring exposed to winter treatments; c) survivorship data for offspring exposed to spring treatments; and d) table with the unique IDs of parents and offspring so individuals in different tables can be matched to their parents/offspring as necessary.
Table of contents
Data files
- parents.csv
- offspring.csv
- egg_mass_area.csv
- maternal_id.csv
- offspring_winter_survival.csv
- offspring_spring_survival.csv
Files and variables
File: parents.csv
Description: this file contains information on the parental generation of Baltimore Checkerspot butterflies (Euphydryas phaeton phaeton), including rearing details, reproductive activity, and responses to thermal treatments.
Variables
- cat_id (numeric): unique identifier of each individual caterpillar.
- treatment (text): treatment that each individual was exposed to: "blue" = 10 °C; "white" = 26 °C; "orange" = 28 °C; "red" = 32 °C.
- maternal (numeric): identifier indicating the maternal lineage of each individual; used to account for non-independence among individuals from the same maternal line.
- sex (text): sex of each individual.
- laid (date, MM-DD-YY): date that eggs were laid.
- hatch (date, MM-DD-YY): date on which each caterpillar hatched.
- spring (date, MM-DD-YY): date on which the overwintering caterpillars were transferred to spring thermal conditions.
- pre (date, MM-DD-YY): date on which each caterpillar was first observed as a pre-pupa.
- pupa (date, MM-DD-YY): date on which each individual was first observed as a pupa.
- in (date, MM-DD-YY): date on which each pupa was transferred to treatment condition.
- emergence (date, MM-DD-YY): date on which the butterfly was first observed emerging from the pupa.
- mass (numeric): pupal mass (mg) measured one day after pupation.
- dead (date, MM-DD-YY): date on which each individual was first observed dead.
- notes (text): annotation describing the type of failed emergence or failed reproduction, if any.
- mate (text): possible values are "Y" and "N". "Y" denotes individuals that mated, "N" denotes individuals that did not mate.
- mate_date_1 (date, MM-DD-YY): date on which the butterfly mated for the first time, if any.
- couple_1 (alphanumeric): unique ID of the mating pair that corresponds to the first mating event, if any.
- mate_date_2 (date, MM-DD-YY): date on which the butterfly mated for the second time, if any.
- couple_2 (alphanumeric): unique ID of the mating pair that corresponds to the second mating event, if any.
- mate_date_3 (date, MM-DD-YY): date on which the butterfly mated for the third time, if any.
- couple_3 (alphanumeric): unique ID of the mating pair that corresponds to the third mating event, if any.
File: offspring.csv
Description: this file contains larval mass measurements for offspring of the parental generation listed in parents.csv. Mass was measured during the fall, when offspring were dormant fourth-instar larvae. Each observation represents a group of five caterpillars, randomly sampled from the same egg clutch.
Variables
- treatment (text): treatment to which the parents of the sampled egg clutch were exposed: "b" = 10 °C; "w" = 26 °C; "o" = 2 8°C; "r" = 32 °C.
- clutch (alphanumeric): unique ID of each clutch.
- group (numeric): numeric identifier for groups of five larvae within a clutch. Each clutch was divided into n groups of five larvae for weighing; this value indicates the group number within that clutch.
- mass (numeric): larval mass (mg) of each 5-larvae group.
File: egg_mass_area.csv
Description: this file contains egg mass (clutch) area measurements for individuals listed in parents.csv, estimated from calibrated photographs. For multilayered egg masses, the area of each layer was measured and summed to obtain total area. Only egg masses for which all layers could be clearly identified were included in this file.
Variables
- ID (alphanumeric): unique identifier for each egg clutch.
- treatment (text): treatment to which the parents of the egg clutch were exposed: "blue" = 10 °C; "white" = 26 °C; "orange" = 28 °C; "red" = 32 °C.
- area_1 (numeric): area (mm2) of the first egg mass layer.
- area_2 (numeric): area (mm2) of the second egg mass layer, if present.
- area_3 (numeric): area (mm2) of the third egg mass layer, if present.
- area_total (numeric): total egg mass area (mm2), calculated as the sum of all measured egg mass layers.
File: maternal_id.csv
Description: this file contains the information to match the ids of parents, clutches and couples. Each observation represents a unique egg clutch.
Variables
- treatment (text): treatment to which the parents of the egg clutch were exposed: "blue" = 10 °C; "white" = 26 °C; "orange" = 28 °C; "red" = 32 °C.
- clutch (alphanumeric): unique ID of each clutch. This variable matches (1) clutch variable in offspring.csv, (2) ID variable in egg_mass_area.csv, (3) clutch variable in offspring_winter_survival.csv, (4) clutch variable in offspring_spring_survival.csv.
- motherid (alphanumeric): unique identifier of the female that laid the eggs. This variable matches the cat_id variable in parents.csv.
- fatherid (alphanumeric): unique identifier of the male that sired the eggs. This variable matches the cat_id variable in parents.csv.
- laid (date, MM-DD-YY): date on which the eggs were laid.
- couple (alphanumeric): unique ID of the mating pair. This variable matches variables couple_1, couple_2, and couple_3 in parents.csv.
File: offspring_winter_survival.csv
Description: this file contains survivorship data for offspring exposed to winter treatments. Each observation represents a group of caterpillars sampled from an egg clutch and assigned to one of the winter treatments.
Variables
- clutch (alphanumeric): identifier indicating the egg clutch from which the group of caterpillars was sampled.
- parental_treatment (text): treatment to which the parents of the group of caterpillars were exposed: "blue" = 10 °C; "white" = 26 °C; "orange" = 28 °C; "red" = 32 °C.
- offspring_treatment (text): winter treatment that group of caterpillars was exposed to. Values include "control" (no heatwave), "short" (multiple short heatwaves), and "long" (single prolonged heatwave).
- spring (date, MM-DD-YY): date on which the overwintering caterpillars (offspring) were transferred to spring thermal conditions.
- total_dead (numeric): number of individuals in the group that died after acclimation to spring thermal condition.
- total_survive (numeric): number of individuals in the group that survived after acclimation to spring thermal condition.
- total_n (numeric): total number of caterpillars in the group.
File: offspring_spring_survival.csv
Description: this file contains survivorship data of the offspring individuals that were exposed to spring treatments. Each observation represents a group of caterpillars sampled from an egg clutch and assigned to one of the spring treatments.
Variables
- spring_treatment (text): spring treatments to which the group was exposed. "Control_Frost" corresponds to control diurnal thermal amplitude and incidence of a late frost, "Control_NF" corresponds to control diurnal thermal amplitude and no exposure to late frost. "Extreme_Frost" corresponds to large diurnal thermal amplitude and incidence of a late frost, "Extreme_NF" corresponds to large diurnal thermal amplitude and no frost.
- id (alphanumeric): unique identifier of each clutch/treatment combination.
- clutch (alphanumeric): identifier indicating the egg clutch from which the group of caterpillars was sampled.
- parent_treatment (text): treatment to which the parents of the group of caterpillars were exposed: "b" = 10 °C; "w" = 26 °C; "o" = 28 °C; "r" = 32 °C.
- n_start (numeric): sample size at start of experiment (total number of caterpillars in the group).
- dead_day1 (numeric): count of caterpillars that died the first day of the experiment.
- april_5 (numeric): count of caterpillars that died on April 5th, 2024.
- april_24 (numeric): count of caterpillars that died April 24th, 2024.
- april_30 (numeric): count of caterpillars that died April 30th, 2024.
- may_7 (numeric): count of caterpillars that died May 7th, 2024.
- may_13 (numeric): count of caterpillars that died May 13th, 2024.
- may_21 (numeric): count of caterpillars that died May 21st, 2024.
To assess the effect of parental thermal environment on offspring performance, a total of 415 pupae from five maternal lines were weighed and randomly assigned to four constant temperature treatments (10 °C, 26 °C, 28 °C, and 32 °C) under a 12:12 L:D cycle beginning on June 6, 2023. Pupae remained in the treatments for 3 days, after which they were maintained at 26 °C until emergence. Pupal mortality, time to butterfly emergence, and emergence success (measured by full wing expansion) were recorded by treatment.
Offspring thermal conditions: WinterSixty siblings were selected from each egg clutch and randomly assigned to one of the three treatment groups: control conditions (0 ± 5 °C), multiple short winter heatwaves (0 ± 5 °C interrupted every 10 days by 3 consecutive days of 11 ± 5 °C) and one long winter heatwave (0 ± 5 °C interrupted by 15 consecutive days of 11 ± 5 °C).
Offspring thermal conditions: SpringWe implemented a 2 × 2 factorial design to combine two aspects of spring weather: the amplitude of the diurnal thermal oscillation which determines the temperature range experienced by individuals, and the incidence of a late frost. We implemented two thermal regimes consisting of diurnal sinusoidal oscillations with either a low amplitude (Mean ± 5 °C ), which is typical for the study area, or a high amplitude (Mean ± 10°C ). Mean temperatures in these regimes resemble average daily spring temperature conditions observed from 1995-2023 (U.S. Federal Government, 2025). All treatments began at an average temperature of 5.7 °C on March 27, 2024, and to simulate progressive spring warming, the average temperature was increased by 3.6 °C every 20 days, consistent with the local typical increase in spring temperatures (U.S. Federal Government, 2025). Starting on April 18th, 2024, larvae were exposed to either the control treatment (i.e., no frost) or to frost conditions (two consecutive nights with temperatures below 0 °C) representative of frost events recorded in Massachusetts in 2021, 2022, and 2024. The timing of the frost events in the treatment group was consistent with observed late frost events in the region from historical NOAA data. Larvae included in this experiment overwintered under the control conditions described in the section above (Offspring thermal conditions: winter). After implementation of spring regimes, larvae were counted weekly to assess mortality until May 29th, 2024.