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About Species and "Unique" Varieties

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First, I should confess that I approach the whole question of taxonomy or classification with the bias of an evolutionary biologist. Specifically, I'm inclined to think of a "species" as one or more populations of something which interbreed with each other and do not or cannot interbreed with others. I.e., there is a geneflow barrier between this group and other groups. From an evolutionary perspective this is very important, of course, because it defines a "unit" of evolution ... anyone inside the group can potentially exchange genes with anyone else in the group to produce new offspring and so that "pool" of genes is that on which selection operates.

Now, the rest of biology doesn't operate this way ... and, to be truthful, some of my former colleagues in biological anthropology don't either. To much of biology "species" is simply one level in a hierarchy of classification with genus and family above it and subspecies and populations below it. No special assumptions are made about geneflow and quite often two plants or animals which are from different species are actually interfertile and thus crosses or intermediate forms are possible. This drives me nuts, but I can't change it, so I'm stuck with what other people do when operating in a realm like this.

Plants, if anything, are "worse" than animals in this regard, particularly cultivated ones since humans are constantly messing around with the reproduction process. At the extreme with grapes we have propagation without sexual reproduction by budding resulting in clones which are genetically identical. Of course, sometimes that which is called a clone is really a "selection" since more than one original plant is included in the propagation and thus the offspring are not genetically identical. (See this Swan Winery Newsletter for a nice discussion of the various terms.)

So, we are starting off with a large number of grape "varieties" classified into multiple species and even genera ... and they are all interfertile ... and people have been mucking about crossbreeding them, probably for thousands of years, most of which with no records. I.e., we have very little idea what we have and how it got that way.

Until fairly recently, classifying grapes was mostly a combination of "ampelography" and tradition. Ampelography, relying on the physical characteristics of the vines and grapes, is necessarily imprecise, especially since different climate, soil, etc. can cause the same genes to manifest themselves differently. Not to mention, of course, that there is no magic formula to tell one whether a particular difference is significant or not. Tradition is naturally less precise, especially since a great many crosses were created at times when we didn't even have a modern understanding of genetics.

Mixed up in all of this is a lot of local color ... take a grape from one country and move it to another and there is a good chance that someone will decide to change its name to something that fits the local language. Plant that grape in Alsace and have many years of the land changing hands between the French and the Germans and this can get very colorful. And, of course, the whole history of Europe and many other wine growing regions is full of moving political and language boundaries.

Now, of course, we have The Answer -- DNA testing. Well, sort of an answer, anyway. Given two or more sets of samples from two or more possible varietals, one can decide that they either seem to be the same or they seem to be different. Now, it isn't really quite that simple, of course, since we don't really have any standards for how different things can be and still be considered the same. E.g., what happens if one starts using DNA testing on all the Pinot Noir "clones" ... might they end up being so different in some cases that one wouldn't call them both Pinot Noir?

And, how similar is similar enough to be considered identical? I think of Zinfandel, Primativo, and Crljenak Kaštelanski where it appears that Zinfandel and Crljenak Kaštelanski, while historically related with Crljenak Kaštelanski as the parent, have had over 100 years with no on-going geneflow, but lots of selection, human and natural, among the Zinfandel grapes. With most organisms, one would expect that to have produced a certain amount of genetic diversity such that one would want to both recognize the parentage, but also the uniqueness of the offspring.

We just have precious few rules established at this point and that is hardly surprising since we know from other organisms that a single mutation can result in no geneflow, lack of interfertility, true evolutionary divergence ... so how can we have a clear scale for deciding what is "different enough"?

On top of which, only a tiny percentage of known grape varieties have been tested so, mostly we just don't have the data. And, most of the testing is taking a small number of possibilities and comparing them to each other, without comparing them to the universe of other things that have also been tested. Important and interesting work, but scratching the surface of the problem.

Consequently, there is a lot in this database and the source materials from which it is drawn that is not clear, hard science. I am noting elsewhere a number of examples where our only source is tradition and that tradition is not clear so we are left with ambiguity. For someone "simply" trying to tally up their list of 100 "unique" varieties, this can be frustrating, but it is also the current state of the science, so we can't simply apply some simple rule and make it all clear.