Forager-farmer transition at the crossroads of East and Southeast Asia 4900 years ago

Neolithic to Bronze Age human maternal genetic history in Yunnan, China

Yunnan in southwest China is a geographically and ethnically complex region at the intersection of southern China and Southeast Asia, and a focal point for human migrations. To clarify its maternal genetic history, we generated 152 complete mitogenomes from 17 Yunnan archaeological sites. Our results reveal distinct genetic histories segregated by geographical regions. Maternal lineages of ancient populations from northwestern and northern Yunnan exhibit closer affinities with past and present-day populations from northern East Asia and Xizang, providing important genetic evidence for the migration and interaction of populations along the Tibetan-Yi corridor since the Neolithic. Between 5500 and 1800 years ago, central Yunnan populations maintained their internal genetic relationships, including a 7000-year-old basal lineage of the rare and widely dispersed haplogroup M61. At the Xingyi site, changes in mitochondrial DNA haplogroups occurred between the Late Neolithic and Bronze Age, with haplogroups shifting from those predominant in the Yellow River region to those predominant in coastal southern China. These results highlight the high diversity of Yunnan populations during the Neolithic to Bronze Age.

Different trajectories of floristic diversity in forested and open landscapes in China over the past 20,000 years

Recently accelerating rate of biodiversity change has triggered exploring the trajectory of plant diversity change from a paleoecological perspective, but the discrepancy and cause of long-term diversity trends from distinct landscapes or ecosystems are largely unknown. Given this, the present study used 41 pollen records from China to investigate the trajectories of plant diversity changes in two distinct land-cover types, i.e., forest and open landscapes, over the past 20,000 years, and discussed the relative roles of long-term climate and anthropogenic land-use changes on plant diversity dynamics. Our results unraveled different trajectories of richness and evenness, and inconsistent relationships between richness and evenness in forest and open vegetation. We speculated that these discrepancies were caused by different mechanisms that structure the communities. At a general level, dispersal and migration processes were more important for diversity change in open vegetation, whereas species competition was more important in forest. Trends of temporal β diversity show a basically consistent pattern, indicating that the rates of change in diversity were comparable between the two landscapes on multi-millennium time scales. Anthropogenic land-use change controlled trajectories of diversity change in both landscapes during the Holocene but its effects have not yet overridden the cumulative impact of climate change since the last deglaciation. Our study unraveled that plant diversity dynamics over the past 20,000 years was primarily a result of the changes in compositional turnover, which emphasizes the need for a regional approach to conservation planning that focuses not only on species losses but also on species replacements.