Late Pleistocene variation in lignin and fatty acids from core TKN-2004 in a small mountain basin in central Japan

Abstract

We generated a record of lignin and fatty acid compositions from the TK-2004 core in Takano Basin, central Japan, during 39-162 ka by TMAH-thermochemolysis-GC/MS. We tested lignin and fatty acid compositions in the sediments of a small lake (1.88 km 2 watershed) as a paleovegetation proxy to understand the responses of terrestrial vegetation in central Japan to global climate change. Variation in terrestrial organic carbon contents estimated by C/N and ∑8 was parallel to the total organic content (TOC) variation, suggesting that the inflow of terrestrial organic matter was a major factor determining the TOC. The ratio of mid-chain C 20 -C 24 n-fatty acids to short-chain C 14 -C 18 n-fatty acids (MFA/SFA ratio) and the ratio of cinnamyl to vanillyl phenols (C/V ratio) of lignin gradually increased from mid-MIS 6 to early MIS 3. The increase in both parameters suggested increase in the contribution of submerged and floating plants as the flats were expanded in the lake margin. The ratio of syringyl to vanillyl phenols (S/V ratio) corresponded to the pollen vegetation index. This correspondence indicated that the S/V ratio reflected the relative abundance of angiosperms to gymnosperms in the Takano Basin. The consistency of the S/V ratio at the site of core TKN-2004 and the other two locations suggests that the S/V ratio in a small basin is a robust proxy for terrestrial vegetation on a regional scale.

Late Pleistocene climate change and population dynamics of Japanese Myodes voles inferred from mitochondrial cytochrome b sequences

“…Kohli et al (2015) considered the time period of 45,000 years for the expansion of M. rutilus from the Eurasian continent, accounting for paleoclimatic evidence in which the Verkhoyansk Mountain Range in northeastern Siberia was covered with ice during the glacial period of 80,000–55,000 years ago. While there are several instances of transitions between warmer and colder periods during the late Pleistocene (Hedges and Mann 1979; Igarashi and Oba 2006; Yamamoto et al 2014), MIS 4 may be one of the most prominent in terms of the coldness that is essential to bottleneck events. Accordingly, the fairly strong influence of the paleoclimate on the two M. smithii haplotype groups distributing in central Honshu (IIId-1) and the coast of central-to-western Honshu (IIId-2) are predicted to have occurred during MIS 4.…”

Estimation of Evolutionary Rates of Mitochondrial DNA in Two Japanese Wood Mouse Species Based on Calibrations with Quaternary Environmental Changes

“…3B (d = 0.0049 T + 0.17). Calibrations (x 1000 years ago) were set in consideration of the vegetative changes during the last ice ages (Igarashi and Oba, 2006;Yamamoto et al, 2014). Evolutionary rates (μ, substitutions/site/million years) were estimated using the formula d = 2Tμ.…”

“…Considerable vegetative changes during the last ice ages have been well demonstrated using various lines of evidence. For example, in a lake in central Honshu, Japan, an index of the contributions of angiosperms versus gymnosperms (S/V ratio; Hedges and Mann, 1979) showed peaks during interglacial periods (e.g., mid-MIS 5e, the MIS 5d/5c boundary, MIS 5a, and early MIS 3) (Yamamoto et al, 2014). Taking into account the vegetative fluctuations, including those in the past 130,000 years, one can specify the five periods that are associated with high values of the pollen temperature index the ratio of temperate taxa (e.g., Quercus) to all taxa (temperate + subalpine taxa) (Kanauchi et al, 2007); 129,000-119,000, 115,000-100,000, 82,000-76,000, 53,000-49,000, and 15,000-0 years ago ( Fig.…”

Quaternary Environmental Changes Shaped Mitochondrial DNA Diversity in the Large Japanese Wood Mouse Apodemus speciosus in Hokkaido, Japan

“…Meanwhile, Hanazaki et al (2017) investigated the local population dynamics of the small Japanese wood mouse A. argenteus based on variation among mtDNA sequences and assessed population expansion events. Considering fossil pollen data (Igarashi et al 1993;Igarashi and Oba 2006;Igarashi et al 2011;Igarashi 2013Igarashi , 2016 and fatty acid compositions (Yamamoto et al 2014), Hanazaki et al (2017 determined that a critical stage in the onset of population expansion occurred during early MIS 3 (ca. 53 000 years ago).…”