that ( i ) SARS - CoV-2 genomes are overall conserved under purifying selection .
A spatial and temporal landscape of 54 critical mutants is constructed
Interrogating 22,078 SARS - CoV-2 genome sequences of 84 countries , we demonstrate with convincing evidence that ( i ) SARS - CoV-2 genomes are overall conserved under purifying selection .
A spatial and temporal landscape of 54 critical mutants is constructed based on their divergence among viral haplotype clusters , of which multiple mutants potentially conferring viral transmissibility , infectivity and virulence of SARS - CoV-2 are highlighted .