Fig. 2

PCR amplification of 18S rRNA genes from eDNA extracted from 299 marine sediment samples. A Success or failure of PCR amplification of 18S rRNA gene in every sample. Red and gray circles indicate PCR success and failure, respectively. Only the plots for which sediment ages are available are shown in the lower panel. The red dashed squares indicate successful amplification from all Expedition 347 sediment samples known to be younger than 105 years. B The summary of PCR success rates in the oxic and anoxic sediments. C The summary of PCR success rates in the three different sediment depth classes, 0–10, 10–100, and 100–677.9 mbsf. D The PCR success rates in the four different sediment age classes, 0–0.1, 0.1–1, 1–10, and > 10 million years ago