Drought-driven lipid deficits in overwintering monarch butterflies revealed by δ²H and fatty acid analysis
Data files
Jan 31, 2026 version files 72.38 KB
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README.md
5.80 KB
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S1._Monarch_Wing_H.csv
8.54 KB
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S2._Monarch_Abdomen_Mass__Lipid_Mass_Fraction_and_Lipid_Mass.csv
13.39 KB
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S3._Monarch_Abdomen_FA_proportions.csv
18.70 KB
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S4._Monarch_Abdomen_H.csv
10.35 KB
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S5._Monarch_Correlation_Analysis_with_Mass_Fraction.csv
15.60 KB
Abstract
Eastern populations of monarch butterflies (Danaus plexippus) overwinter in the central trans-volcanic belt of Mexico, relying primarily on lipids accumulated during migration to sustain this several-month-long overwintering period. This study examined how drought conditions in north-central Mexico influenced lipid dynamics in monarchs overwintering in Sierra Chincua (Michoacán, Mexico) across two consecutive seasons. Butterflies were collected in 2022-2023 (n = 150), following mildly dry conditions, and in 2023-2024 (n = 180), after an extreme drought affecting the entire Mexican migratory corridor. We measured abdominal mass, lipid mass fraction, lipid mass, fatty acid composition, and the δ2H values of non-essential palmitic and oleic acids as source indicators of dietary energy. In both years, non-essential fatty acids served as metabolic fuel, but all lipid metrics were significantly reduced in the drought year. Correlations between fatty acid δ2H values and content (palmitic = 0.35; oleic = 0.28; p < 0.05) suggested altered nectaring behavior and limited lipid accumulation at high-altitude sites near the overwintering colonies during extreme drought. Fatty acid δ2H values became increasingly negative while lipid levels converged between years by the end of overwintering, possibly due to in situ lipid synthesis or selective mortality. These results highlight the vital role of nectar resources along the Mexican migratory corridor and near overwintering sites in supporting lipid reserves crucial for the survival of overwintering monarchs. While our findings strongly indicate a connection between drought and reduced monarch lipid reserves, we recognize that additional efforts are needed to evaluate nectar quality and floral abundances more effectively to establish causality.
Dataset DOI: 10.5061/dryad.cfxpnvxkn
Description of the data and file structure
Lipid and hydrogen isotopic data for Drought-driven lipid deficits in overwintering monarch butterflies revealed by δ²H and fatty acid analysis.
Isotopic (δ2H) and Lipid content metrics of monarch abdominal lipids in 5 csv files:
S1._Monarch_Wing_H, which contains the δ2H values of male and female monarch wings. These monarchs were collected in two different years at three time points within each overwintering period.
S2._Monarch_Abdomen_Mass__Lipid_Mass_Fraction_and_Lipid_Mass which contains the abdominal mass, abdominal lipid mass fraction and lipid mass of male and female monarch abdomens. These monarchs were collected in two different years at three time points within each overwintering period.
S3._Monarch_Abdomen_FA_proportions which contains the fatty acid proportional composition of lipid in male and female monarch abdomens. These monarchs were collected in two different years at three time points within each overwintering period.
S4._Monarch_Abdomen_H which contains the δ2H values of palmitic and oleic fatty acids in male and female monarch abdomens. These monarchs were collected in two different years at three time points within each overwintering period.
S5._Monarch_Correlation_Analysis_with_Mass_Fraction which contains the δ2H values of palmitic and oleic fatty acids in relation to the mass fraction of respective fatty acid content in male and female monarch abdomens. These monarchs were collected in two different years at three time points within each overwintering period.
Files and variables
File: S5._Monarch_Correlation_Analysis_with_Mass_Fraction.csv
Description:
Variables
- Year: The year from which overwintering monarchs were collected. Year 1 is 2022/2023 and Year 2 is 2023/2024.
- Collection time: The time point within an overwintering period that monarchs were collected. All monarchs were collected either early, midway or at the end of the overwintering period.
- Sex: Monarchs were either male (M) or female (F).
- ID: Within each year ID designates which sampled monarch the data corresponds to.
- PA 2H: The deuterium value of monarch abdominal palmitic acid.
- OL 2H: The deuterium value of monarch abdominal oleic acid.
- PA (ug/mg): The mass fraction (ug/mg of freeze-dried abdominal tissue) of monarch abdominal palmitic acid.
- OL (ug/mg): The mass fraction (ug/mg of freeze-dried abdominal tissue) of monarch abdominal oleic acid.
File: S4._Monarch_Abdomen_H.csv
Description:
Variables
- Year: The year from which overwintering monarchs were collected. Year 1 is 2022/2023 and Year 2 is 2023/2024.
- Collection time: The time point within an overwintering period that monarchs were collected. All monarchs were collected either early, midway or at the end of the overwintering period.
- Sex: Monarchs were either male (M) or female (F).
- ID: Within each year ID designates which sampled monarch the data corresponds to.
- PA 2H: The deuterium value of monarch abdominal palmitic acid.
- OL 2H: The deuterium value of monarch abdominal oleic acid.
File: S3._Monarch_Abdomen_FA_proportions.csv
Description:
Variables
- Year: The year from which overwintering monarchs were collected. Year 1 is 2022/2023 and Year 2 is 2023/2024.
- Collection time: The time point within an overwintering period that monarchs were collected. All monarchs were collected either early, midway or at the end of the overwintering period.
- Sex: Monarchs were either male (M) or female (F).
- ID: Within each year ID designates which sampled monarch the data corresponds to.
- PA proportion: The proportion of palmitic acid comprising lipids of monarch abdomens.
- ST proportion: The proportion of stearic acid comprising lipids of monarch abdomens.
- OL proportion: The proportion of oleic acid comprising lipids of monarch abdomens.
- LA proportion: The proportion of linoleic acid comprising lipids of monarch abdomens.
- ALA proportion: The proportion of alpha-linolenic acid comprising lipids of monarch abdomens.
- EPA proportion: The proportion of eicosapentaenoic acid comprising lipids of monarch abdomens.
File: S2._Monarch_Abdomen_Mass__Lipid_Mass_Fraction_and_Lipid_Mass.csv
Description:
Variables
- Year: The year from which overwintering monarchs were collected. Year 1 is 2022/2023 and Year 2 is 2023/2024.
- Collection time: The time point within an overwintering period that monarchs were collected. All monarchs were collected either early, midway or at the end of the overwintering period.
- Sex: Monarchs were either male (M) or female (F).
- ID: Within each year ID designates which sampled monarch the data corresponds to.
- Ab Lipid Mass fraction (ug/mg):he mass fraction (ug/mg of freeze-dried abdominal tissue) of monarch abdominal lipid.
- Ab Mass (mg): Mass of freeze dried monarch abdomens.
- Ab Lipid Mass (mg): Mass of lipid present in monarchs abdomens.
File: S1._Monarch_Wing_H.csv
Description:
Variables
- Year: The year from which overwintering monarchs were collected. Year 1 is 2022/2023 and Year 2 is 2023/2024.
- Collection time: The time point within an overwintering period that monarchs were collected. All monarchs were collected either early, midway or at the end of the overwintering period.
- Sex: Monarchs were either male (M) or female (F).
- ID: Within each year ID designates which sampled monarch the data corresponds to.
- wing 2H: The deuterium value of monarch wing sample.