The unique climate shapes distinct life-history traits of abundant bacteria in Tibetan Plateau grassland soil.

The unique geographical patterns of the Qinghai-Tibet Plateau have shaped the different climatic characteristics of the Lhasa and Nyang River watersheds. However, our understanding of climate-dependent life history strategies in riparian grasslands is very limited. In this research, we have compared the causes and consequences of variations in the composition of soil abundant and rare bacterial taxa in the Nyang and Lhasa River watersheds. The results showed that the abundant bacteria, rather than the rare bacteria, exhibited distinct life history strategies between the Lhasa and Nyang watersheds that were a consequence of climate patterns. The wetter climate of the Nyang watershed led to a high ratio of r-strategists among the abundant bacteria (Abundant K:r = 0.323), while in the less favourable climate of the Lhasa watershed, K-strategists were more common among the soil abundant bacteria (Abundant K:r = 0.542). The assembly processes of abundant and rare bacteria in the Lhasa region under relatively harsh climatic conditions seemed to be more affected by variable selection than those in the Nyang region. Moreover, abundant bacteria in the Lhasa region developed stronger potentially cooperative relationships and exhibited a stronger metabolic capacity than those in the Nyang region. The 26 different functional genes identified in LS were highly associated with 38 abundant bacterial species. In contrast, the 16 identified functional genes in NY were highly correlated with 16 abundant bacterial species. These results provide new insights into climate-dependent life history strategies of soil bacterial communities with different abundances in riparian grasslands of the Tibetan Plateau. Contrasting the life history strategies of bacterial taxa with different abundances contributes to a better mechanistic knowledge of their impact on ecosystem functioning under current and future effects of global climate change.