Dear Peter, Thanks for the continuing discussion. One the one side, perhaps you are gaining a convert to your idea - however, I will need to consult with the work of Clements & Jones first, and see if I may prefer their version better.
In the meanwhile, let me advance a few thoughts here: 1. Pollinators: I live in the midst of what is thought to be one of the most mature of Floral Kingdoms; the Cape Flora. The ecological sophistication brought to our local plants by an apparently long, little-interrupted evolution as a community, means that we have large numbers of good examples of oligophily - that is, pollination of a species by one to very few species of pollinator - not only amongst the orchids, but in numerous other plant families. For me oligophily is always uppermost in my mind. Of course, the Cape Floral Kingdom is also not the Australasian Tropical Rain Forest. Regarding "One species of carpenter bee is known to cause pollination of several species of large-flowered tropical Asian orchids":- Polytropy (the visiting of a wide range of plant species by one species of pollinator) does not logically exclude oligophily. I agree that the "one orchid species, one insect species" hypothesis is a gross simplification - there are many other factors which need to be taken into consideration, but there is a grain of wisdom in taking this hypothesis as a starting point, and then going out and disproving it in the species being studied. The process of disproving would be, in itself, very revealing. Regarding the significance of flower size in relation to a pollinator; I believe that for any particular flower size, where a number of different flower sizes occur in a group of related plants, correct placement of the pollinaria - so essential to successful pollination - only takes place on an appropriately-sized/shaped insect. 2. As plants are continuously evolving - I like to see a species, paradoxically, as a final product which is a "Perfect work in progress", and about which nothing is final. We see them as they are today. Seeds will fly around the place and make changes down the line. To evaluate breeding barriers in terms of allopatry; one needs to assess things as they are at present - the result of what has gone on so far. Today's species are not tomorrow's species - on a somewhat larger time frame. 3. As I pointed out, "Plants are not mosquitos of course, and their genetic differences seem to hold a different rank to those of animals", so I agree with you here. There appears to be much more of a continuum exhibited in the DNA profiles in plants, when compared to the clipped, defined DNA profiles that can be seen to represent animal species - the latter making the job of the animal taxonomist so much the easier. Finally. We may be comparing apples and onions here. There are a number of forms of "Species". Your taxonomic unit appears to be what is called a "Morphological Species": defined as "the smallest population structurally distinct and distinguishable from all others"; a very practical and pragmatic approach - the only fascile one that can be applied by the compiler of a Regional Flora. My taxonomic unit is probably the "Biological Species": which can be defined as "natural populations of living, reproducing, genetically related individuals isolated from other populations by barriers to gene exchange". This is a lot more airy-fairy - but its elegance appeals to the aberrant proteins that float around in my skull. This approach better suits the compiler of the Monograph of a genus. There are yet other forms of "Species". Regards, greig russell Kommetjie.
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