An argument that only something that isn't descended from within the (very large and expanding) Omicron clade can get a new @WHO Greek letter isn't consistent with the stated criteria, and it misses the point of how evolution works.
1/
1/
Think about birds. In phylogenetic terms, they are nested within "reptiles" (and thus *are* reptiles if "reptiles" is to be a clade and not paraphyletic).
(I talked about clades, monophyly, and paraphyly here:
2/
(I talked about clades, monophyly, and paraphyly here:
https://twitter.com/TRyanGregory/status/1582762102435246084?s=20&t=skPGcIhmT9c6iO6Tdd9loA)
2/
BUT, we talk about birds separately from "reptiles" all the time. Ornithology is not part of herpetology. Why? Because the rate of change in various traits in the avian lineage is much faster and they are quite different from other "reptiles".
3/
3/
With SARS-CoV-2 variants, you could get something very different if it evolves from a deeply divergent branch and not from within Omicron, OR you get some lineages of Omicron that change a lot very quickly. (Also, recombination across distinct lineages could do it).
4/
4/
The Greek naming system was introduced when it was just deeply divergent lineages. But now we have rapid diversification within a clade and the naming hasn't kept pace.
5/
5/
• • •
Missing some Tweet in this thread? You can try to
force a refresh
