Drought-driven lipid deficits in overwintering monarch butterflies revealed by δ²H and fatty acid analysis

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 = 0.3..., , # Drought-driven lipid deficits in overwintering monarch butterflies revealed by δ²H and fatty acid analysis

Dataset DOI: [10.5061/dryad.cfxpnvxkn](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** ***δ*****²H 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 con...,