Fig. 1. Global distribution of abundant Altiarchaeota (group Alti-1) and their predicted viruses in Altiarchaeota hot spots.

Distribution analysis is based on 16S rRNA gene sequencing (yellow dots) and the detection of hamus genes in metagenomes from IMG (blue and purple dots). Purple dots correspond to the four investigated sites of this study. Normalized host and virus coverage are given for the four subsurface habitats: Alpena County Library Fountain (ACLF, Michigan, USA), Horonobe Underground Research Laboratory (HURL, Japan), Mühlbacher Schwefelquelle, Isling (MSI, Germany), and Geyser Andernach (GA, Germany). Percent relative abundance of dominant Altiarchaeota compared to other community members is shown in Supplementary Table 1. Only Altivir_1_MSI and Altivir_2_MSI obtained from biofilm (BF) samples are shown. The letter C indicates circular genomes. n.d. none detected. World map has been generated using Ocean Data View v.5.3.0¹¹⁷. Color explanation of bars representing normalized coverage: orange-red = Altivir_1_MSI (virus), blue = Altivir_2_MSI, purple = Altivir_3_ACLF, rose = Altivir_4_ACLF, brown = Altivir_5_ACLF, light blue = Altivir_6_ACLF, green = Altivir_7_ACLF, and black = Altiarchaeota (host).