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Habitat fragmentation can facilitate local adaptation of species to heterogeneous environments and affect population demographic history. To understand the factors influencing evolutionary dynamics, such as climatic fluctuations and complex geomorphological features, we used 18 chloroplast microsatellites, 15 nuclear microsatellites, three chloroplast fragments, and two nuclear regions to explore the genetic structure and phylogeographical history of Pseudotaxus chienii. Furthermore, its current and past distributions were constructed based on ecological niche modelling. Moderate to high levels of genetic diversity were found at the species level. Precipitation was a decisive factor influencing the genetic structure of P. chienii. In addition, local adaptation to heterogeneous environments also contributed to maintain the fragmented distribution. Finally, incomplete lineage sorting led to the cyto-nuclear discordance. Overall, we show that pre-Quaternary and Quaternary climatic fluctuations and restricted gene flow exerted significant effects on the formation and maintenance of the fragmented distribution of P. chienii. The study provides new insights into the evolutionary history of plants in subtropical China. [ABSTRACT FROM AUTHOR]

Cherries (subg. Cerasus) belong to Prunus s.l. (Rosaceae) and are widely distributed in temperate and subtropical regions of the Northern Hemisphere. Given its ornamental and edible functions, it is a hugely preferred germplasm resource for human societies. However, the interspecific phylogenetic relationships, divergence times, and routes of this subgenus remain unclear. To reveal its enigmatic and intricate evolutionary history, we newly sequenced 12 subg. Cerasus species, reconstructed the plastome phylogeny with 24 previously published subg. Cerasus species. This study supports that subg. Cerasus split into five clades, among which P. mahaleb is the basal group of subg. Cerasus ; P. campanulata is genetically distantly related to P. cerasoides and is not recommended for treatment as a variety of the latter; P. subhirtella is involved in the speciation of P. yedoensis. Molecular dating and ancestral area reconstructions infer that subg. Cerasus originated in the Eastern Mediterranean–Central Asia before 11.57 Mya (95% HPD = 5.34–19.1 Mya) and subsequently spread into the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The first dispersal event of modern subg. Cerasus was facilitated by 'out-of-QTP', colonizing North America across the Bering Land Bridge and re-dispersing into Europe from the Late Miocene to Pliocene and forming the initial distribution pattern of extant subg. Cerasus in the Pliocene; The end of the Quaternary glacial period witnessed a second dispersal event, and core subg. Cerasus population diversity flourished radially in its separate refugia during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

The geographical distributions of the two cryptic species of the wetland moss Hamatocaulis vernicosus were mapped for western, central and northern Europe, based on identifications of the two by the nuclear ITS1 + 2 and the plastid rpl16 and trnL–trnF. The distributions of the two cryptic species overlap to a large extent. However, in the west and south-west only cryptic species 1 is present, whereas in the boreal north only cryptic species 2 occurs, which agrees with its distribution in Scandinavia. Despite these differences in distribution, no differences between the two cryptic species were revealed in habitat water chemistry, elevation distribution or climatic niches. The difference in distribution therefore suggests that cryptic species 1 could have survived the glacial period in southern Europe and cryptic species 2 in northern or eastern Europe. However, the studied molecular markers did not reveal geographical patterns suggesting origins in different glacial refugia. Although populations of both cryptic species have decreased in large portions of western Europe, a significantly negative Tajima's D may reflect the long-term expansion south of Scandinavia since the glacial bottleneck, potentially correlated with the expansion of earlier extensive agricultural management of wetlands. [ABSTRACT FROM AUTHOR]