[Taxacom] Lynn's taxa (was: clade age)

Lynn Raw lynn at afriherp.org
Fri Nov 11 11:17:52 CST 2011


Hi Ken,

The original distribution (and habitat) was narrow and so these individual isolates do not extend far enough upstream to meet. In the area further upstream where the valleys are shallow and the overall habitat is fairly uniform there is a related but distinct species. These species all seem mutually exclusive and there is no evidence of any interbreeding. Calling them subspecies does not seem the right approach on that basis.

On 11 Nov 2011, at 14:25, Kenneth Kinman wrote:

Hi Lynn,                 
         Sounds like a case of subspeciation, but not
necessarily speciation.  Since they are morphologically distinct, one
could certainly justify naming them (at least as subspecies).     

     But if the differences in morphology are caused by few genes (as
few as one), then chances are that such mutations would not have
resulted in an inability to interbreed.  I just wonder if more intensive

sampling in upstream areas might reveal areas where some of these taxa
actually still meet and interbreed (where the valleys are not as deep).                 
                  -----------Ken  

                                  
---------------------------------------------- 
Lynn Raw wrote: 
         The second question was not theoretical. It
resulted from the geosynclinal uplift of a once single habitat followed
by the incision of deep river valleys that has resulted in 7
morphologically distinct, dare I call them, taxa. DNA studies were
unable to separate them, my guess is that this looked at a stable
sequence in this group that did not change. Perhaps choosing another
region could show some differences but I can see just how a tree /
cladistic approach would not be able to deal with it. 



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