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Estimating vegetation sensitivity during the Holocene will improve the predictions of future vegetation dynamics. We compiled 52 pollen sequences from the monsoon-influenced northern China to reconstruct the Holocene dynamics of three forest types dominated respectively by Pinus, Quercus and Betula, as well as steppe and desert indicated respectively by Artemisia and Chenopodiaceae. The sensitivities of these vegetation types to changes in intensity of the East Asian monsoon were calculated according to the elevation, temperature and precipitation groupings of sites. Our results show that the Holocene vegetation dynamics differed across vegetation types, with Pinus and Quercus at lower elevations more sensitive to monsoon-induced precipitation changes and Betula at higher elevations more sensitive to temperature changes at the beginning of the Holocene. We also found an increasing sensitivity for forests and steppe within different groups following evident reduction in monsoon intensity since 5 ka BP, caused most probably by climate drying in this drought-determined forest-steppe in northern China. Besides regional scale forest retreat caused by climate drying, elevational movement as well as site expansion and decline are also suggested to explain low vegetation sensitivities in some site-groups. Our study provides insights into the mechanisms of individualistic responses of plant taxa as well as the asymmetrical response of ecotonal vegetation to the Holocene monsoon development in China. [ABSTRACT FROM AUTHOR]

Background: Worldwide feralization of crop species into agricultural weeds threatens global food security. Weedy rice is a feral form of rice that infests paddies worldwide and aggressively outcompetes cultivated varieties. Despite increasing attention in recent years, a comprehensive understanding of the origins of weedy crop relatives and how a universal feralization process acts at the genomic and molecular level to allow the rapid adaptation to weediness are still yet to be explored., Results: We use whole-genome sequencing to examine the origin and adaptation of 524 global weedy rice samples representing all major regions of rice cultivation. Weed populations have evolved multiple times from cultivated rice, and a strikingly high proportion of contemporary Asian weed strains can be traced to a few Green Revolution cultivars that were widely grown in the late twentieth century. Latin American weedy rice stands out in having originated through extensive hybridization. Selection scans indicate that most genomic regions underlying weedy adaptations do not overlap with domestication targets of selection, suggesting that feralization occurs largely through changes at loci unrelated to domestication., Conclusions: This is the first investigation to provide detailed genomic characterizations of weedy rice on a global scale, and the results reveal diverse genetic mechanisms underlying worldwide convergent rice feralization.