Locality data

Jim McKenney jamesamckenney@verizon.net
Tue, 30 Oct 2012 15:39:56 PDT
Leo wrote: " I have been led to believe we name species based on differences in plant structures,not geography."

What Leo wrote is certainly an accurate description of the way things have been done in taxonomy for centuries. 

However, once genetics emerged as a science, the time honored  primacy of morphology (structures) was challenged by a radically different concept, the concept of the gene pool. What the gene pool concept asserts is that species, at least in theory, are determined by the limits of their breeding population (gene pool), not by their appearance (i.e. structures, morphology). 

>From my point of view, contemporary DNA studies are fairly viewed as a  minutely granular version of morphology ( maybe better thought of as "meta-morphology"). And from that point of view, DNA studies are no better suited for determining species limits than traditional gross morphological studies.  Why? Because morphological studies, no matter how detailed, do not address or answer the questions which determine the boundaries of the breeding population. To be sure, morphological studies can accurately determine when two entities are NOT the same species, but morphology in and of itself cannot determine when two entities ARE of the same species (although morphology/DNA studies can provide highly probable guesses).  

Where does geography fit into this? Breeding populations typically have a discrete geographical range. In areas where only one species of a genus occurs, if you know the geographic source of the entity, you know the specific identity. In areas where sympatric species occur (i.e. multiple related species in the same area) then you have to resort to traditional morphological distinctions for purposes of identification. 

Jim McKenney

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