[Taxacom] Diagnosing species

[Ken Kinman]

Richard,
     I'll get to the "younger subspecies" idea, but first a little 
speculation.  It's not surprising to me that corals are more like plants in 
retaining speciation "messiness".  Corals are very primitive metazoans and 
also sedentary as adults.  Even among more derived bilaterian metazoans, I 
would expect some sedentary forms (like bryozoans, bivalves, and even 
arthropod barnacles) might share some of this plesiomorphic "messiness" with 
plants.  In some ways (including reduced speciation "messiness"), active 
forms like insects and vertebrates would share certain evolutionary trends 
such as the ability to be more selective in their mate selection.  After 
all, they not only share an active life-style, but eyes to examine 
prospective mates.  So even though eyes may be "polyphyletic" among Metazoa, 
the possession of eyesight (as well as mobility) may produce convergent 
trends in mate selectivity that makes many insects more like vertebrates in 
having less speciation "messiness", while primitive (sedentary and eyeless) 
metazoans like sponges and corals are more like plants.

    As for "younger" subspecies, the way I look at it is that a species 
begins as a small single subspecies.  As it expands geographically and in 
numbers, the original population is likely to change very little compared to 
later developing ("younger") populations or subspecies that are invading new 
territories.  Therefore I look at it as a mother subspecies giving rise to 
daughter subspecies.  If they speciate, they simply become mother species 
and daughter species.  The mother group originates first, and is therefore 
older, and staying in the original area means it is probably going to change 
less.  Therefore, I would say the tendency to fix mutations would not only 
be affected by population size, but perhaps more significantly by living in 
a slightly different habitat with a different mix of challenges and 
resources (even IF the daughter population eventually exceeds the mother 
population in size).
    -----Ken
*********************************
Richard Pyle wrote:
>I guess it depends on which animals you're talking about.  Corals seem to 
>be
>more like plants.  I have a hunch (not much more than that, at this point)
>that we'll eventually come to recognize this sort of "messiness" among reef
>fishes.  But of course, vertebrates are the exception, not the rule.  In 
>the
>world of animals, it seems to be really all about insects, when it comes to
>speciation.
>

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