Ostracod Genetic Variability in Response to Lake Level‐Driven Salinity Dynamics in Nam Co, Central Tibetan Plateau, in the Past Two Millennia

Ecology and Evolution, vol. 15, pp. e72706

Abstract

ABSTRACT Sedimentary ancient DNA metabarcoding has revolutionized the reconstruction of past lake biodiversity, providing insights into species assemblages spanning thousands of years. We apply this approach to investigate ostracod community dynamics and genetic diversity in a two‐millennia sedimentary record from Nam Co, the third largest lake on the Tibetan Plateau, where hydrological fluctuations have driven shifts in salinity and habitat conditions. Using stratigraphic sedaDNA analyses, temporal diversity indices, and environmental proxies, we linked ostracod assemblages to lake‐level and climatic changes. Species richness peaked between 628 and 765 CE during moister conditions with increased minerogenic influx, and again since the mid‐1970s amid recent warming and glacier‐melt–driven lake‐level rise. In the earliest sedaDNA record (~230 BCE ), Tonnacypris gyirongensis indicated warm, nutrient‐rich, shallow estuarine conditions. Between ∼600 and ∼830 CE , Candona candida and Ilyocypris angulata reflect freshwater, organic‐rich littoral habitats. During the Medieval Climate Anomaly (~948–1143 CE ) and Little Ice Age (~1600–1678 CE ), alternating dominance of Limnocythere sp. and Leucocytherella sinensis primarily signals changes in water level and salinity due to their different ecological tolerances. Genetic data reveal generally low lineage diversity in parthenogenetic taxa, punctuated by transient increases in phylogenetic diversity during moister intervals at the end of the Late Antique Cold Period (490–830 CE ), the late Medieval Climate Anomaly period (1250–1400 CE ), and recent warming. Sediments spanning the Little Ice Age exhibit stable richness but shifts in dominance patterns, indicating a change in salinity and alkalinity. Since the 1950s, a marked turnover has occurred with declining L. sinensis and rising Limnocythere inopinata , coinciding with reduced monsoon runoff; in contrast, the post‐1970s freshening has promoted the resurgence of L. sinensis , alongside minor occurrences of I. angulata and L. inopinata . Our results demonstrate the sensitivity of Tibetan Plateau ostracod communities to hydrological and climatic variability. By integrating sedaDNA with paleoenvironmental proxies, we reveal both community‐level and intra‐species genetic responses to past climate change, underscoring the power of sedaDNA metabarcoding for paleoecological and evolutionary research.

Authors 13

1. Katharina Dulias corresponding

   Technische Universität Braunschweig

   Affiliation as printed

   Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany

2. Sten Anslan

   University of Jyväskylä

   Affiliation as printed

   Department of Biological and Environmental Science University of Jyväskylä Jyväskylä Finland

3. Luis Victoria Nogales

   Technische Universität Braunschweig

   Affiliation as printed

   Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany

4. Anja Schwarz

   Technische Universität Braunschweig

   Affiliation as printed

   Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany

5. Wengang Kang

   Chinese Academy of Sciences · Institute of Tibetan Plateau Research

   Affiliation as printed

   Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

6. Paula Echeverría‐Galindo Aachen Institute of Organic Biogeochemistry in Geo-Systems

   RWTH Aachen University

   Affiliation as printed

   Institute of Organic Biogeochemistry in Geo‐Systems (OBG) RWTH Aachen University Aachen Germany

7. Nicole Börner

   Technische Universität Braunschweig

   Affiliation as printed

   Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany

8. Ping Peng

   Chinese Academy of Sciences · Institute of Tibetan Plateau Research

   Affiliation as printed

   Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

9. Yongqin Liu

   Chinese Academy of Sciences · Institute of Tibetan Plateau Research

   Affiliation as printed

   Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

10. Keshao Liu

    Chinese Academy of Sciences · Institute of Tibetan Plateau Research

    Affiliation as printed

    Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

11. Bernd Wünnemann

    Southwest Jiaotong University · Technische Universität Braunschweig

    Affiliation as printed

    Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu China

    Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany

12. Junbo Wang

    Chinese Academy of Sciences · Institute of Tibetan Plateau Research

    Affiliation as printed

    Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

13. Antje Schwalb

    Technische Universität Braunschweig

    Affiliation as printed

    Institute of Geosystems and Bioindication Technische Universität Braunschweig Braunschweig Germany