Fig. 6

Microdiversity and positively selected genes. A Genome-level microdiversity indicated by π values. B Gene-level microdiversity indicated by π values. C Selection pressures of viral genes indicated by pN/pS values. D Percentage of genes under positive selection (i.e., pN/pS > 1). E Categories of viral genes under positive selection in cryopeg brine (CB) and sea ice brine (SB). Left pie graph, all genes are divided into two groups: genes under positive selection and purifying selection based on pN/pS values. Middle pie graph, genes under positive selection are divided into annotatable and un-annotatable groups by comparing to genes in databases. The number of genes in the above groups is indicated in parentheses after the group names. Right pie graph, the annotatable genes from the middle pie graph are grouped into different gene categories. The percentage of genes assigned to different categories is indicated after the category name. Sample labels: CB, cryopeg brine; SB, sea ice brine; SW: seawater