Four digestion protocols were tested: H2O2, KOH and enzymes Trypsin and Proteinase-K (Table SI.1). Adaptations were made as follows: consistent with the Proteinase-K protocol (Cole et al., 2014), tissues were freeze-dried prior to digestion. Additionally, the cost and hazardousness of reagents and time expenditure of each method were compared to establish the most suitable digestion technique (see supplementary information ‘Costs, time needed and hazardousness of reagents’).