Vegetation Reconstruction From Siberia and the Tibetan Plateau Using Modern Analogue Technique–Comparing Sedimentary (Ancient) DNA and Pollen Data

Abstract

To reconstruct past vegetation from pollen or, more recently, lake sedimentary DNA (sedDNA) data is a common goal in palaeoecology. To overcome the bias of a researcher’s subjective assessment and to assign past assemblages to modern vegetation types quantitatively, the modern analogue technique (MAT) is often used for vegetation reconstruction. However, a rigorous comparison of MAT-derived pollen-based and sedDNA-based vegetation reconstruction is lacking. Here, we assess the dissimilarity between modern taxa assemblages from lake surface-sediments and fossil taxa assemblages from four lake sediment cores from the south-eastern Tibetan Plateau and northern Siberia using receiver operating characteristic (ROC) curves, ordination methods, and Procrustes analyses. Modern sedDNA samples from 190 lakes and pollen samples from 136 lakes were collected from a variety of vegetation types. Our results show that more modern analogues are found with sedDNA than pollen when applying similarly derived thresholds. In particular, there are few modern pollen analogues for open vegetation such as alpine or arctic tundra, limiting the ability of treeline shifts to be clearly reconstructed. In contrast, the shifts in the main vegetation communities are well captured by sedimentary ancient DNA (sedaDNA). For example, pronounced shifts from late-glacial alpine meadow/steppe to early–mid-Holocene coniferous forests to late Holocene Tibetan shrubland vegetation types are reconstructed for Lake Naleng on the south-eastern Tibetan Plateau. Procrustes and PROTEST analyses reveal that intertaxa relationships inferred from modern sedaDNA datasets align with past relationships generally, while intertaxa relationships derived from modern pollen spectra are mostly significantly different from fossil pollen relationships. Overall, we conclude that a quantitative sedaDNA-based vegetation reconstruction using MAT is more reliable than a pollen-based reconstruction, probably because of the more straightforward taphonomy that can relate sedDNA assemblages to the vegetation surrounding the lake.

Sedimentary ancient DNA reveals past ecosystem and biodiversity changes on the Tibetan Plateau: Overview and prospects

“…From the above examples and our prior studies on many lake surface sediments (Jia et al, 2022;Liu et al, 2021e;Stoof-Leichsenring et al, 2020, we conclude that future applications of plant DNA metabarcoding on the Tibetan Plateau seem promising. Worth mentioning is that more projects on terrestrial and aquatic plants from other lakes, such as Lake Ximenco, Lake Mugeco, Lake Qionghai, and Lake Donggi Cona (Fig.…”

Plants, pollinators and their interactions under global ecological change: The role of pollen DNA metabarcoding

“…Pollen preservation in ancient sediments, in combination with ancient sedimentary DNA (Capo et al, 2021 ), provides a resource for understanding past ecosystems. Usually, the pollen grains are examined morphologically, while the sediments are analysed through DNA sequencing to provide complementary data sources (Liu et al, 2021 ; Parducci et al, 2017 ). The ability to access the DNA inside pollen grains, for either single pollen grain analysis or DNA metabarcoding, would enable investigation of population dynamics in ancient ecosystems, something which is otherwise not possible in plants.…”

Pollen DNA metabarcoding and related methods in global change ecology: prospects, challenges, and progress

“…Pollen preservation in ancient sediments, in combination with ancient sedimentary DNA (Capo et al, 2021), also provides a resource for understanding past ecosystems. Usually, the pollen grains are examined morphologically, while the sediments are analysed through DNA sequencing to provide complementary data sources (Liu et al, 2021;Laura Parducci et al, 2017). This approach has been used to determine conservation baselines for offshore islands in New Zealand (Wilmshurst et al, 2014).…”

“…For example, the presence of pollen in environmental samples can be used to determine plant species composition, which can be helpful for surveying changes in biodiversity (Leontidou et al, 2021;Matthias et al, 2015), comparing current ecosystems to historical samples (Gous, Swanevelder, Eardley, & Willows-Munro, 2019;Simanonok et al, 2021), the early detection of biological invasions (Tremblay et al, 2019), and monitoring airborne allergenic pollen impacting human health (Suanno, Aloisi, Fernández-González, & Del Duca, 2021). Pollen can also be used to assess changes in phenology (Burkle et al, 2013), detect plant-pollinator interactions (Bänsch et al, 2020;Gresty et al, 2018;Kaluza et al, 2017;Lucas, Bodger, Brosi, Ford, Forman, Greig, Hegarty, Jones, et al, 2018;Richardson et al, 2021;Sponsler, Shump, Richardson, & Grozinger, 2020), reconstruct pollen transport networks (Tur, Vigalondo, Trojelsgaard, Olesen, & Traveset, 2014), and reconstruct past vegetation and, from this, climate (Courtin et al, 2021;Liu et al, 2021;Niemeyer, Epp, Stoof-Leichsenring, Pestryakova, & Herzschuh, 2017;Laura Parducci et al, 2019). The identification of pollen from the bodies of animals is particularly useful for the reconstruction of plantpollinator interaction networks because it increases the temporal scale of information obtained, leading to more connected networks than those reconstructed through observations of flower visitation (Arstingstall et al, 2021;Bosch, Gonzalez, Rodrigo, & Navarro, 2009;de Manincor et al, 2020).…”