Taxonomic Merge 125936
(הועלה ב 2023-05-16)
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@pieterwinter The varieties are not recognized in either POWO or FNA. What authorities do you know of which accept them?
Coleman, J. R. 1974. Verbesina section Ximenesia (Compositae): biosystematics and adaptive variation. Amer. J. Bot. 61:25-35.
GRIN Taxonomy for plants
I would say the FNA treatment superceeds any work from 1974.
USDA taxonomies are also not very modern.
Also USDA.
That's what I mean, GRIN is a product of the USDA, and therefore, not very modern.
Is there any evidence that these are not similar yet non-interbreeding species? Even if only a few observations are identified to that level, it would make it easier to update the data in cases where infraspecific names are later raised to species level. As a general practice, I recommend that if iNat recognized a subspecies, it should not be changed until there is good evidence that there is no breeding barrier whatsoever.
Not that I'm aware of. This evidence doesn't exist for for almost all species, let alone infraspecies, so if that was the threshold we'd basically never be able to do anything with curating subspecies.
In that case I would think that the precautionary principle should apply. If it doesn't itch, don't scratch. Science does not progress based on opinion, but on evidence-based rationale only.
I am curious about the assumption behind the objective of "curating subspecies". What is the intended outcome of such curation?
I mean, it's kind of well known that early authors created many subspecies / varieties based on poor evidence or a very limited quantity of material (e.g. finding a single population with white flowers and creating a alba variety). There is no evidence that this hypothetical variety is distinct from the rest of this hypothetical species in any character except flower color. At some point you have to get rid of these superfluous subspecies or they just make a big, confusing taxonomy which is not based on evidence itself.
Here's such an example (from http://floranorthamerica.org/Lepidium )
"Lepidium species are reasonably well-defined worldwide, and taxonomists often find no problems in telling them apart. The infraspecific taxonomy, especially some of the North American species, is in a state of disarray. The main reason is dependence on characters of questionable value to establish most varieties. For example, glabrous and pubescent forms were almost always recognized as distinct varieties despite the fact that they occur within the same population. The painstaking work of R. C. Rollins (1958) on Dithyrea clearly demonstrated that the presence versus absence of trichomes can result from a minor genetic difference. Rollins (1993) and others (e.g., N. H. Holmgren 2005b) were influenced by the excellent work of C. L. Hitchcock (1936, 1945, 1950), who then had no idea about the genetic basis of such differences. A similar situation exists in Draba, where tens of varieties were established based on glabrous versus pubescent fruits. In this account, we do not recognize such varieties, and the interested reader is referred to the discussion under 35. L. ramosissimum."
Please cite a reference that provides sound evidence to establish conclusively that this merge is inevitable.