ddRAD-Seq of Spermophilus citellus
For DNA extraction, we used the commercial GeneJET FFPE DNA Purification Kit (ThermoFisher Scientific), following the manufacturers protocol. The genomic library was produced using the ddRAD sequencing protocol (Peterson et al., 2012). A suitable combination of restriction enzymes (SphI, EcoRI) was determined by analysing in silico reference genomes of Spermophilus species. The ddRAD sequencing was performed by IGA Technology Services (Italy) in paired-end mode using a NovaSeq 6000 sequencer (Illumina, San Diego, CA).