Message 2004-06-0011: RE: LITU, and lineage names

Mon, 14 Jun 2004 14:35:37 +0200

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Date: Mon, 14 Jun 2004 14:35:37 +0200
Subject: RE: LITU, and lineage names

Hi, folks,
i post a short debate with Fredrik Pleijel [hi, Fredrik!], to know where =
*you* stand...

>> I would vote for your LITU's: at long last, a clean concept appeared! =

>> We paleobiologists (paleontologists, if you wish) face another =
>> we got used to consider "species" being parts of phylogenetic =
>> between two apomorphies -- and we need names for them. These are not =
>> unlike LITU's, so what we should do? Although extant "species" can =
sure be=20
>> transformed into clades, non-terminal extinct ones can not.=20
>> Just as clades are defined by single nodes, these "chronospecies" are =

>> the internodia, or their parts. Yes, and we need names to refer to =
>> (and there is to be much more these "chronospecies" than =
>> (actually as many as independent apomorphies recognized)).
>> Litu has no sense when you include time within the play:=20
>> what is LITU today will become a clade tomorrow (read: after =
radiation event(s)).

> I would say LITUs certainly make sense when you include time (after=20
> all, we are historicians). A LITU does not make any absolute=20
> statement=20
> about the group being indivsible, it only states that it's=20
> the smallest=20
> (least inclusive) group that we have recognised at present (whether=20
> recent or extinct). The moment someone subdivides it, it=20
> ceases to be a=20

however, it is not the entity I would like to refer to: I need to =
*exclude* all
its decsent that differs!

> As for the species problem in palaeontology, I think it's just a=20
> special case of a much larger one, namely identifying paraphyletic=20
> groups.=20

If I got it right: yes, "species" is, by definition(s ;-), a =
paraphyletic group of individuals
as it can evolve into other "species"

> I just don't think we should recognise them as taxa, and that=20
> for a number of reasons, possibly the most important being that we=20
> don't know what we're naming - 1 lineage, or 100 different lineages,=20
> only united by their lack of diagnostic features? That is the problem=20
> one runs into in the case you mention with "species" being parts of=20
> phylogenetic lineages between two apomorphies. My view is that we=20
> should know something about the things we label... And when we think=20
> about it, how important is it to name all of these 'things" that we=20
> don't know much about in  terms of lineages? What do they permit to=20
> conclude?=20
usually, only that entity1 differs from entity2 :-( but, isn't it enough =
for a name?
surely we should *not* mix these entities (whatever they are called) =
with clades,
and perhaps we should *not* include them (recall: speaking about =
"species") within the phylocode.
then, however, I would vote for a "Nomenclature for Species", making =
these two independent,
for the sake of clarity -- of course biologists should refer to them =
both, but I am against
expressing (hypothesized) clade membership within the "species" names -- =
put the connections to the database.
Thus, we can have, e.g.:
	merula (Aves: Turdus)=20
as a name and hypothesized relationship, as it can appear in papers...
or something alike.
> For the rare cases when it really is important to relate to=20
> them, then I would just use an informal name. But I guess I'm in=20
> minority...

Love to know your opinion(s),

Peter A. Cejchan
Lab of Paleobiology and Paleoecology
Prague, EU



Feedback to <> is welcome!