Fig. 3

Richness, abundance, and diversity profiles of representative genes in different cold seep sites. In the bar graphs of functional genes, the red bars on the left signify richness, which is scaled with the left y-axis, representing how many distinct GSCs are present for that particular functional gene. The blue bars on the right signify abundance, which is scaled with the right y-axis, indicating the average number of reads that successfully mapped to the reference sequences of the corresponding functional gene at the cold seep site. The middle ^qD profiles depict the taxonomic diversity, specifically referring to the diversity of GSCs, while the ^qPD profiles on the right represent the phylogenetic diversity. Different colors of the curves correspond to distinct cold seep sites. ^qD and.^qPD vary in order q which determines the measures’ sensitivity to GSC relative abundances. The weight assigned to GSCs with higher relative abundance augments as the q-value increases. Smooth curves indicate high evenness. The colors of functional gene names represent the metabolic processes in which they participate. a–c mcrA for anaerobic oxidation of methane (orange). d–f dsrA for dissimilatory sulfate reduction (green). g–i nifH for nitrogen fixation (blue). j–l narG, and m–o nosZ for denitrification (light blue)