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Re: New AVES definition refined (more testable?)
Paraphrasing (I think), you're saying that it is inappropriate
to make a list of characters and conclude that a species which
has X number of those characters must be related to another species
or group of species.
Your reason is that:
<As far as I know, some genetic agent that groups a certain number
of characters together, then expresses a random sampling of them
in every generation, is not known.>
My knowledge is hardly thorough enough to insist on the point,
but isn't it possible to say that (just inventing) someone's
descendants may be identified by either or both of two uniquely
shaped birthmarks? It is theoretically possible to have alternative
unique connections, no?
Also, and more significantly, as a lineage evolves through time,
some of the characters which linked a species to its ancestors
may disappear. Part of the complexity of cladistic logic is
that of linking one species to another, which in turn has characters
which help to identify certain characters as derived/shared from
the mrca. Thus, a descendant species need not have many of the
identifying marks of an ancestral species to be included.
The list of characters linking two species may not be the same
as the list of characters linking those species to their mrca,
In that sense, if you drew up a list of characters used in establishing
a whole hypothesis of relationships, some of those animals would
have some items on the list and others not.
If I'm reading you correctly, your observation is about the question
'Are these two species related' as opposed to the question, 'Do
these two species share a common ancestor?'
Cladistic logic, as I tromp along in its path, has an amazing
number of conditional assumptions and complex associations.
Parsimony is certainly the simplest part.
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