I blasted sars2 against sars and against ratg13. 88% coverage for the first and 99% for the second, so ratg13 seems to be a much more recent ancestor.
- sars2 v. sars: https://blast.ncbi.nlm.nih.gov/Blast.cgi?CMD=Get&RID=D7WE9PB...
- sars2 v. ratg13: https://blast.ncbi.nlm.nih.gov/Blast.cgi?CMD=Get&RID=D7WGNJG...
Why would ace2 be much better preserved between sars2 and sars than between sars2 and ratg13?
Apologies for being dense :) As you notice, I'm pretty new to bioinformatics. Just trying to understand what your argument is.
UPDATE: Sorry, I see a mistake I've been making that is confusing. I should be referring to Bat_CoV_ZC45 and Bat_CoV_ZXC21, not ratg13. ratg13 is the one that also has a close match to ace2, but the author claims is a forgery. The bat coronaviruses also seem to be more evolutionarily close to sars2 than sars, and they don't have the ace2 binding sites.