We tested the variability in content of ALA and EPA, and of total lipids in macroinvertebrates across all sampling sites (i.e., category with 6 levels – 3 streams ´ 2 populations [allopatric, sympatric]) and subsidy types (category with 2 levels – aquatic or terrestrial macroinvertebrates). Since there was no difference lipid quality of aquatic and terrestrial subsidies across the six sampling sites (see results for details), we did not include the stream or sampling site in the models. We collected samples of dorsal and ventral muscle tissue because concentration of adipose cells is usually higher in ventral than in dorsal muscles and thus these two tissues can differ in their lipid content (Fauconneau et al. 1995; Ebm et al. 2021). However, the total lipid content and the relative content of n-3 LC-PUFA were repeatable across dorsal and ventral muscle samples (total lipids: Radj = 0.25, 95% CI [0.06, 0.44]; ALA: Radj = 0.59, 95% CI [0.44, 0.72]; EPA: Radj = 0.62, 95% CI [0.48, 0.74]; DHA: Radj = 0.56, 95% CI [0.41, 0.70]. Therefore, for further analysis we have used an average value across tissues for each individual. Total lipids in all models were reported as mass fractions (mg/g of the dry mass), while all models and figures including n-3 LC-PUFA reported the relative fatty acid contents (% of fatty acid methyl esters; with exception of Fig. 1). This is a common approach (e.g., Twining et al. 2019; Ebm et al. 2021) because mass fractions of fatty acids are often closely correlated to the total lipid mass fractions, while the relative content of fatty acids is independent of the total lipids and thus more comparable across the sample types and studies, particularly when only a part of an organism (e.g., muscle tissues) is analysed.