Section Costatae (genus Betula) raw sequence reads

Delineating closely related and morphologically similar species is difficult. Here, we integrate morphology, genetics, ploidy and geography to resolve species and subspecies boundaries in four trees of section Costatae (genus Betula): Betula ashburneri, Betula costata, Betula ermanii and Betula utilis (including ssp. utilis, and diploid and tetraploid races of ssp. albosinensis).