Climatic Fluctuation of Marine Isotope Stage 9: A Case Study in the Southern Margin of the Chinese Loess Plateau

Marine Isotope Stages(MIS) 9 has been proposed as an analog for the present warm period. However, detailed studies of this geological time period are rare in loess-paleosol sequence. In the Chinese Loess Plateau(CLP), the corresponding stratum is the third paleosol layer(S3). Here, we report the terrestrial reconstruction of climatic fluctuations during MIS 9 by analyzing the paleo-climate indexes of S3 with high sampling density. Our results showed that:(1) During the period of MIS 9, the main climatic sub-cycle was 29 ka;(2) MIS 9 could be divided into five sections, MIS 9a, 9b, 9c, 9d, and 9e. Among them, MIS 9a, 9c, and 9e were warm stages, while MIS 9b and 9d were cool intervals;and 3) There were also three swift warm-wet events and one cool-dry event, which occurred around 332 –331, 324–323, 311–310, and 331–329 ka BP, respectively. The overall trend of paleo-climate fluctuation correlated approximately with SPECMAP, LR04 stack and Iberian margin deep-sea cores. This study suggested that the paleosol records in the southern margin of the CLP have global significance and contain more detailed climatic signals than marine deposits.

Effects of climate fluctuations on runoff in the headwater region of the Kaidu River in northwestern China

The aim of this study was to analyze the effects of climate fluctuations on runoff in the headwater region of the Kaidu River in northwestern China. For this purpose, precipitation and potential evaporation （PET） data from 5 meteorological stations and the runoff depth data from the Dashankou hydrological station in the headwater region of the Kaidu River from 1960 to 2009 were collected, then the trends and abrupt changes of precipitation, PET and runoff depth were analyzed by means of Mann-Kendall test （M-K test） and Mann-Kendall-Sneyers test （M-K-S test）, respectively. The runoff model driven by precipitation and PET was developed in this work and the sensitivity of runoff to climate fluctuation was simulated under different scenarios. Results showed that the annual precipitation and runoff depth both exhibited an increasing trend over the periods 1960-2009; however, this is not the case for the annual PET. The abrupt changes for annual precipitation, PETand runoff depth all occurred in the early 1990s. The established driving model could well reflect the compli- cated nonlinear relationship among runoff depth, precipitation and PET. The sensitivity analysis indicated that the precipitation had a positive effect on the runoff depth, opposite to what were observed between PET and runoff, and the runoff depth was more sensitive to precipitation than to PET in the headwater region of the Kaidu River.

Spatial dynamics of Chinese Muntjac related to past and future climate fluctuations

Climate fluctuations in the past and in the future are likely to result in population expansions,shifts,or the contraction of the ecological niche of many species,and potentially leading to the changes in their geographical distributions.Prediction of suitable habitats has been developed as a useful tool for the assessment of habitat suitability and resource conservation to protect wildlife.Here,we model the ancestral demographic history of the extant modern Chinese Muntjac Muntiacus reevesi populations using approximate Bayesian computation(ABC)and used the maximum entropy model to simulate the past and predict the future spatial dynamics of the species under climate oscillations.Our results indicated that the suitable habitats for the M.reevesi shifted to the Southeast and contracted during the Last Glacial Maximum,whereas they covered a broader more northern position in the Middle Holocene.The ABC analyses revealed that the modern M.reevesi populations diverged in the Middle Holocene coinciding with the significant contraction of the highly suitable habitat areas.Furthermore,our predictions suggest that the potentially suitable environment distribution for the species will expand under all future climate scenarios.These results indicated that the M.reevesi diverged in the recent time after the glacial period and simultaneously as its habitat's expanded in the Middle Holocene.Furthermore,the past and future climate fluctuation triggered the change of Chinese muntjac spatial distribution,which has great influence on the Chinese muntjac's population demographic history.

Inter-glacial isolation caused divergence of cold-adapted species:the case of the snow partridge

Deciphering the role of climatic oscillations in species divergence helps us understand the mechanisms that shape global biodiversity.The coldadapted species may have expanded their distribution with the development of glaciers during glacial period.With the retreat of glaciers,these species were discontinuously distributed in the high-altitude mountains and isolated by geographical barriers.However,the study that focuses on the speciation process of cold-adapted species is scant.To fill this gap,we combined population genetic data and ecological niche models(ENMs)to explore divergence process of snow partridge(Lerwa lerwa).Lerwa lerwa is a cold-adapted bird that is distributed from 4,000 to 5,500 m.We found 2 genetic populations within L.lerwa,and they diverged from each other at about 0.40–0.44 million years ago(inter-glacial period after Zhongliangan glaciation).The ENMs suggested that L.lerwa expanded to the low elevations of the Himalayas and Hengduan mountains during glacial period,whereas it contracted to the high elevations,southern of Himalayas,and Hengduan mountains during inter-glacial periods.Effective population size trajectory also suggested that L.lerwa expanded its population size during the glacial period.Consistent with our expectation,the results support that inter-glacial isolation contributed to the divergence of cold-adapted L.lerwa on Qinghai-Tibetan Plateau.This study deepens our understanding of how climatic oscillations have driven divergence process of cold-adapted Phasianidae species distributed on mountains.