Restriction-site associated DNA (RAD) sequencing of dwarf birches from the Arctic and southern refugia, using Illumina single-end libraries
We present RADseq short read data of the dwarf birch species Betula nana L. and B. glandulosa Michx., and of the shrub birch species B. humilis Schrank. The Dwarf birches are abundant tundra deciduous shrub species that are implicated in the ongoing Arctic vegetation greening trends. Plant leaves were collected in the field from plants identified by morphology as B. nana, B. glandulosa, and B. humilis. Genomic DNA was extracted, and quality control resulted in 244 samples from 48 populations. A subset of samples were duplicated (between 1-3 duplicates per sample) to increase sequencing coverage, resulting in 376 DNA extracts in total. Libraries were prepared for all individuals using restriction enzyme Pstl and selecting fragments between 300-500 bp. These were sequenced on four lanes of an Illumina NovaSeq 6000 using 1x100 bp single end reads. Library preparation and sequencing were conducted by Floragenex (Beaverton, Oregon).  After filtering and genotype calling, mean effective per-sample coverage was 346 x (min 99.7, max 1031).