Grasshopper DNA extraction and sequencing
We collected samples from multiple populations from either side of theP. pedestris hybrid zone. For long-term storage, hindlegs were kept in pure ethanol at 4℃. After equilibrating these in deionised water on ice for ten minutes with their exoskeleton cut open, we extracted whole genomic DNA using a Blood & Tissue Kit (Qiagen, Manchester, UK). TruSeq sequencing libraries were generated by, and sequencing was carried out at the Bart’s and the London Genome Centre on the NextSeq 500 platform generating paired-end reads of 76 nt length. The sequencing coverages obtained ranged from 5.6% to 35.6% with a median of 7.4%.