that ( i ) SARS - CoV-2 genomes are overall conserved under purifying selection .
Notably , genes <*> are under adaptive evolution
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 .
Notably , genes related to coronavirus infection and host immune system defense are under adaptive evolution while genes related to viral RNA replication , transcription and translation are under purifying selection .