Fig. 5

Summary of ERV sequence clustering. a Number of ERV-ORF clusters associated with each ERV-ORF domain. The x-axis represents the sequence identity established via clustering. The y-axis represents the number of clusters and also shows the original number of sequences before clustering occurred (gray shaded area) for comparison. A logarithmic scale was used on the y-axis. b Pairwise comparison of shared sequences clustered at ≥60% identity level in 19 mammalian species. The color bar represents the number of shared sequences. Gray indicates that no shared sequences were identified. C) The number of ERV-ORF sequences in each cluster containing at least one human ERV-ORF identified in the CHESS database. The x-axis represents clusters with ≥60% identity; however, the cluster name is not shown due to limited space. Individual bar colors indicate which ERV-ORFs in each cluster are derived from which species shown in Fig. 1a [e.g. Apes (blue) contain ERV-ORFs from human, chimpanzee, gorilla, and/or orangutan]. Clusters containing ERV-derived genes are indicated by red triangles and the specific gene name. d ERV-ORF clusters shared among at least eight species at ≥60% identity levels. Domain names are shown on the top. Clusters containing ERV-ORFs with transcriptional potential (purple triangle) and known genes (red triangle) are highlighted. The red-scale color bar represents the percent identities for sequences against a reference sequence within the cluster. The highest identity in each species is shown. Blue represents the absence of a specific sequence in the given cluster. The clusters containing human ERV-ORFs with transcriptional potential (purple triangle) and known mammalian ERV genes (red triangle) were indicated on the top of heatmap. The amount of sequences forming single-species clusters (middle) and those that failed to form any cluster (right) are also shown for each species