[Taxacom] Phylogenetic Classification?

[Winston Edwards]

Hi John,

"Most molecular phylogenies will not reveal this problem (or at best only
hint at it) because they sample only one individual of each species."

Actually, most molecular phylogenetic studies use more than one individual
per species, and if they didn't, I wouldn't really trust their results.
There are a huge number of molecular population studies using coalescence
theory that you may want to look at.

Sincerely,

Winston T. Edwards

On Fri, Jul 31, 2009 at 12:23 PM, Kenneth Kinman <kennethkinman at webtv.net>wrote:

> Hi John,
>         Paraphyletic species are very common among both animals and
> plants.  Homo erectus is the paraphyletic mother species of our own
> species Homo sapiens.  I simply classify it as the species Homo erectus%
> (the % symbol indicates it's paraphyletic), and then divide it into
> subspecies plus a {{Homo sapiens}} marker showing which of those
> subspecies it probably evolved from.
>       In a phylogenetic analysis of species, the cladogram would most
> likely show them as sister species, and I suspect strict cladists most
> often simply don't realize the paraphyly exists and or don't dig enough
> to find out.  When they do recognize the paraphyly, I believe that they
> sometimes apply the name "metaspecies" to the paraphyletic mother
> species.  I have no problem with that if they don't want to call it
> paraphyletic and having a term metaspecies would make it more palatable.
> However, I do have a problem with strict cladists who don't even like
> metaspecies and want to split up this mother species into additional
> species just to solve the unwanted paraphyly.  The phylogenetic species
> concept thus recognizes a lot more species than an evolutionary species
> concept.  At least such splitting seems to be a lot more common than
> their other alternative (lumping the daughter species into the mother
> species).  I'm not sure what strict cladists plan to do with Homo
> erectus, but I suspect that they would advocate splitting it up.
>        ----------Ken Kinman
> -----------------------------------------------------------
>
> John Boggan wrote:
> Maybe this has already come up but I don't have the time or patience to
> wade through all the discussion in the archives.  How are paraphyletic
> species to be treated in strictly cladistic classifications?  I don't
> know about animals, but in plants paraphyletic species are probably
> quite common, i.e., one or more morphologically distinct and
> reproductively isolated species have been derived from a common and
> widespread ancestral species that still exists.  Recognizing those
> derived species makes the ancestral species paraphyletic, but it is
> still a species (or is it?) in that it consists of interbreeding
> populations that are united by gene flow while reproductively isolated
> from their relatives (including the descendant species).  Should the
> derivative species be synonymized under the ancestral species?  And if
> not, what are the phylogenetic implications of the subsequent history of
> these two taxa, one monophyletic but the other not?
>
> Most molecular phylogenies will not reveal this problem (or at best only
> hint at it) because they sample only one individual of each species. But
> taking the problem to a reasonable extreme, it's theoretically possible
> for a single founding individual of a species, landing on an island, to
> undergo an evolutionary radiation and give rise to numerous new genera
> and species even while the ancestral species still exists on the
> mainland, remaining more or less unchanged.  In practice, extinction of
> populations and entire species probably saves us from this problem. But
> if it could be shown that the founding individual (and thus all its
> descendants) was more closely related to one population of the ancestral
> species than another, the classification of that group could get awfully
> messy...
>
>
>
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