[Taxacom] Elimination of paraphyly: sensible or not?

[John Grehan]

In response to Stephen's assertion that  "Perhaps the elimination of
paraphyly is being driven instead by economic factors, doing phylogenies
being a more cost efficient way for institutional scientists to spend their
time on than alpha taxonomy?" I would have to ask what economic factors are
driving my work where I consciously look to construct non paraphyletic
groups? I certainly spend a lot of time on alpha taxonomy but not in a
phylogenetic void. So where are my economic rewards? Of course I duly note
that Stephen says 'perhaps' which also means 'perhaps not' so perhaps no
one knows either way anyway, or perhaps not :)

John Grehan

On Thu, Feb 8, 2018 at 5:42 PM, Neal Evenhuis <neale at bishopmuseum.org>
wrote:

> I had a similar discussion with a pattern cladist once and his response
> was “Hey, you’ve got a point …. but if you comb your hair differently, it
> won’t show.”
>
>  -Neal
>
> On Stardate 2/8/18, 12:07 PM, Star-trooper "Taxacom on behalf of Stephen
> Thorpe" <taxacom-bounces at mailman.nhm.ku.edu<mailto:taxacom-bounces@
> mailman.nhm.ku.edu> on behalf of stephen_thorpe at yahoo.co.nz<mailto:
> stephen_thorpe at yahoo.co.nz>> wrote:
>
> Hi all,
> I have been giving some thought to the cladistic obsession of eliminating
> paraphyly in taxonomic classification. For many taxa (above species), the
> subtaxa consist of one or more clearly monophyletic groups, plus a possibly
> paraphyletic residue (i.e. no apomorphies to bind the residue together into
> a monophylum). So, if we must eliminate paraphyly (or possible paraphyly),
> the only options are to either: (1) subsume the monophyletic subtaxa into
> the paraphyletic residue; or (2) break up the paraphyletic residue into
> monophyletic subtaxa. Effectively the two options may actually be
> equivalent. An example might help to illustrate my point. Let's take a
> simplistic view of reptiles as scaly tetrapods, birds as feathery winged
> bipeds derived from reptiles, and mammals as hairy tetrapods derived from
> reptiles. So, amniotes (reptiles, birds and mammals) are a monophyletic
> group, as are birds and also mammals, but not reptiles (reptiles being the
> "paraphyletic residue"). We wish to retain birds and also mammals as useful
> monophyletic taxa, for obvious reasons. So, what to do? Luckily, within
> reptiles there are some monophyletic subgroups of sufficient diversity to
> be useful, but this might not have been the case if all reptiles were just
> basically "skinks", with only species or perhaps also generic differences
> between them. Had this been so, amniotes would have to be taxonomically
> split between numerous (maybe hundreds) virtually identical taxa of
> "skinks", plus birds and also mammals as just two taxa at the same level
> (not necessarily a ranked level, but direct child taxa of amniotes). Would
> this be a useful classification of amniotes? I suggest that it would be far
> more useful to recognise a single paraphyletic taxon of reptiles (all the
> "skinks" in the hypothetical example), plus birds and also mammals (i.e.
> just 3 direct child taxa of amniotes). I wonder for plants, fungi and also
> invertebrates, if there might be many taxa analogous to the above
> hypothetical example, with a paraphyletic residue consisting of hundreds of
> "skinks", but also with just one or two very distinct and diverse
> monophyletic subtaxa? If so, would it be sensible to eliminate paraphyly or
> best just to live with a known paraphyletic residue as a unified subtaxon?
> Given the amount of limited resources which are being allocated to projects
> to eliminate paraphyly, to the detriment of alpha taxonomy, it would be
> nice to think that there was a clearly good reason for the elimination of
> paraphyly, but I'm not so sure that there is! The usual argument seems to
> be that you cannot make meaningful predictions from paraphyletic taxa, but
> how much biology does rely on the making of predictions based on taxon
> membership, and what proportion of those predictions end up being true
> anyway? For example, you might predict that a newly discovered braconid is
> a parasitoid, but a few braconids are phytophagous anyway. So, I guess that
> the main question that I am posing is whether we think that the benefits of
> monophyly justify the spending of so much limited resources on the
> elimination of paraphyly? Perhaps the elimination of paraphyly is being
> driven instead by economic factors, doing phylogenies being a more cost
> efficient way for institutional scientists to spend their time on than
> alpha taxonomy?
> Stephen
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