A complex biosystematic approach to reveal evolutionary and diversity patterns in West Asian brambles (Rubus subgen. Rubus, Rosaceae)

Abstract

West Asia, with its high mountain ranges and glacial refugia, stands out as a biodiversity hotspot for various plant taxa, including the taxonomically complex Rubus subgen. Rubus. Despite this significance, our understanding of the evolutionary processes shaping this group in the region has been limited. We employed an integrative approach combining flow cytometry, Sanger sequencing of two plastid regions, microsatellite genotyping, and double digest restriction-site associated DNA sequencing to characterize evolutionary and diversity patterns in West Asian brambles. We identified four diploid and two sexual tetraploid species, with the remaining diversity comprising apomictic tetra- and triploids, mostly belonging to R. ser. Discolores, and sexual pentaploid hybrids/hybridogens derived from R. caesius. Rubus dolichocarpus, newly reported here as diploid, emerged as a significant ancestor for many polyploids. Most apomictic genotypes are locally distributed and only three genotypes exhibit extremely large ranges from Armenia to Kyrgyzstan and from Georgia to Iran. These genotypes are probably of an ancient (Pleistocene) European origin and likely laid the foundations for the evolution of apomicts in West Asia, whose diversification was subsequently boosted by the genetic contribution of sexual taxa. DNA markers confirmed the West Asian origin of Rubus armeniacus, a globally significant invasive species, yet rare in its native range. We report on the first indigenous occurrence of this species based on microsatellite genotyping. Our findings contribute to filling existing gaps in understanding the evolution and diversity of Rubus subgen. Rubus in West Asia.