Re: [dinosaur] Party like it's 1758!

[David Marjanovic <david.marjanovic@gmx.at>]

Gesendet:ÂSamstag, 13. Juni 2020 um 04:05 Uhr
Von:Â"Paul P" <turtlecroc@yahoo.com>

> Phylogenetic nomenclature has its own set of problems. For example, things 
> like "the clade originating in the most recent common ancestor of A and B" 
> becomes a mess if A or B turns out not to belong to that clade.

You mean if the phylogenetic hypothesis of the day changes so much A or B may 
be said not to belong to the taxon, as traditionally understood, which has 
traditionally borne the name in question?

One half of the answer is everything Mickey has said.

The other half is that steps can and should be taken both to prevent such 
situations, and to remedy them once they do arise. The most important mechanism 
of prevention is peer review. Unlike the zoological or the botanical code, the 
phylogenetic code _requires peer review_ as a prerequisite for the validity of 
any nomenclatural act (Article 4.2). Where that isn't enough, definitions can 
be amended, in some cases by just another peer-reviewed publication, in others 
by the Committee on Phylogenetic Nomenclature*, which also has the power to 
suppress or conserve names.

* ...to which I currently belong; you can join the Society and vote me out in 
2022. :-)

> And the termite example given in the press release in support of the 
> Phylocode is silly--termites could simply have been demoted to suborder or 
> infraorder instead of family. In fact, I think they were. Nothing else has to 
> change.

That is not so. The first sentence of the Wikipedia article "Termite" is:

"Termites are eusocial insects that are classified at the taxonomic rank of 
infraorder Isoptera, or as epifamily Termitoidae within the order Blattodea 
(along with cockroaches)."

Here we already see several parts of the problem. First, in the zoological 
code, all taxon names at ranks in the family group _have to_ be formed from the 
name of the type genus. There _cannot_ be an epifamily called Isoptera. Second, 
Isoptera doesn't have a type genus, because (under the zoological code) only 
taxa at ranks in the family group have such a thing; upon demotion into the 
family group of ranks, a type genus had to be chosen and the choice published 
as a nomenclatural act. In this case it's obvious enough that the type genus 
should be *Termes*. But, to pick two examples from my field, Microsauria and 
Cotylosauria both drifted over the decades to end up excluding the genera they 
were originally erected for.

Third, within the infraorder Isoptera, the classification presented in the 
Wikipedia article recognizes a parvorder called Euisoptera, which in turn 
contains a nanorder called Neoisoptera. This illustrates another problem: there 
are never enough ranks for all the clades people want to talk about and 
therefore name, but a name without a rank does not officially exist under the 
rank-based codes. The article as it currently stands fails to notice the fourth 
problem: you can have a parvorder (above the family group of ranks) inside an 
infraorder, but not inside an epifamily (in the family group of ranks). There 
don't seem to be any superfamilies recognized, so I suppose Neoisoptera could 
be Superfamily Termitoidea, and Euisoptera could be given another rank invented 
by Gaffney in the 1980s (hyperfamily?) and renamed to something with Termit- as 
well.

In short, the decision of whether the termites should be an infraorder or an 
epifamily is not merely arbitrary, it causes cascading changes in the _names_ 
of other taxa up and down the tree. Rank-based nomenclature really is based on 
the ranks.

Under the PhyloCode this problem does not exist. Call Iguanidae (registration 
number 52) a family or a superfamily or a suborder or nothing at all, its name 
does not change, and the previous Iguaninae cannot become Iguanidae as a side 
effect.

> Many groups are already defined phylogenetically.

In some fields like ours, yes. But this wasn't regulated until now â it can 
and does happen _even in situations where everybody agrees on the phylogeny_ 
that different people use different names for the same clade (even the same 
definition) or different definitions, which apply to different clades, for the 
same name. This leads to completely unnecessary confusion which the PhyloCode 
stops: once a combination of name and definition is validly published & 
registered, it's official, and any other uses of that name or that definition 
can be treated as wrong.