SIGNATURE WORK
CONFERENCE & EXHIBITION 2023

Cyanobacterial harmful algal blooms (CyanoHABs) are widely distributed environmental threats and their currently increasing intensity is believed to be caused by their exceptional biological functions and the related environmental changes, especially the anthropogenic eutrophication. This eco-physiological interaction has been well confirmed, but the evolutionary explanations on how cyanobacteria acquire those biological functions and whether human activities contribute to it are still unstated. This study investigated various bloom-forming cyanobacteria by applying evolutionary and phylogenetic analyses on their whole and core genomes. The results indicated that cyanobacterial genes related to bloom-forming abilities have not been positively selected by anthropogenic elevated nutrient level. Phylogenetic results reveal that closely related species/strains are found in distant geographic regions despite their shared bloom-forming abilities, which suggests the absence of positive selection on related genes. Selection pressure analysis also supports this result since all cyanobacterial species share similar dN/dS and r2N//r2S values that are close or less than 1 for housekeeping and bloom-related genes. Therefore, it is likely that the genetic foundation of bloom-forming related biological functions were gained by cyanobacteria before anthropogenic eutrophication.