s*, infecting, respectively, the beluga whale and birds. To date there is no evidence of coronavirus infection in reptiles, even if the presence of a *Letovirinae* coronavirus in amphibians encourage more coronavirus investigation in reptiles. Coronaviruses infecting human can cause mild respiratory symptoms and conjunctivitis ([@B10], [@B11]), such as *Human coronavirus 229E* and *Human coronavirus NL63* (*Alphacoronavirus*), or mild enteric and respiratory disease, such as *Betacoronavirus 1 OC43* and *Human coronavirus HKU1* (*Betacoronavirus*); whereas *Severe acute respiratory syndrome-related coronavirus* (SARS) and *Middle East respiratory syndrome-related coronavirus* (MERS), both belonging to *Betacoronavirus*, can cause severe disease and are example of spillover of animal viruses to human. COVID-19 associated virus was recognized by CSG as forming a sister clade to the prototype human and bat severe acute respiratory syndrome coronaviruses (SARS-CoVs) of the species *Severe acute respiratory syndrome-related coronavirus*, and it was designated as SARS-CoV-2 ([@B12]).

The considerable diversity of coronaviruses is driven by their genetic and evolutionary features. Specifically, mutation and recombination appear to be particularly important in coronavirus evolution ([@B13]--[@B16]). As RNA viruses, CoVs tend to accumulate random mutations at a far higher rate than their hosts. In spite of the proofreading-repair activity of their polymerase, increasing copying accuracy up to 14-fold ([@B17]), coronaviruses form mutant spectra (mutant clouds, quasispecies); viral populations consisting of dynamic and complex mutant distributions, rather than unique genomic sequences ([@B18]). Quasispecies correlate to enhanced virulence and evolvability and render difficult to prevent and control viral diseases. The ability to exist as mutant clouds in an individual host have been described both in animal CoVs, such as the bovine enteric and respiratory coronaviruses ([@B19]) and in human SARS-CoV ([@B20], [@B21]). Furth