----- Original Message ----- From: "Peter O'Byrne" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Sunday, August 29, 2004 4:35 PM Subject: Dendrobium bigibbum, D. phalaenopsis, and allies
Dear Peter, Thanks for your very reasoned, excellent reply. I do like a lot of what you are saying, and I think I can understand all your points. There are good reasons to lump all the plants into a single species. That is, if you are a lumper. I like to attempt to see the picture from what I hope to be an evolutionary point of view. While these taxa certainly must have been a single species in the past, I wonder whether they have evolved separately for just long enough to now have developed separate ways of making a living. Are they all using the same pollinator? Are there barriers in place which prevent the admixing of the DNA of the various taxa? There certainly is allopatry in play here - the New Guinea-form and the Timor Laut-form cannot share their DNA with the Australian forms, or each other, they live too far away? As for the smaller flowered compactum, one can assume (from a distance) that they are utilising a smaller species of insect to effect pollination. The pollinators are always important - I believe that insects are the World's best taxonomists - and anyone wishing to understand the relationships between related plants should ask insects for their view: ie. see who is doing what to whom. I see your insistence that there be two consistently different characters as a bit limiting. DNA studies are now showing, for example, that some "species" of mosquitos in fact comprise four genetically, absolutely distinct species. They all just look the same even though they could never breed with one another at all. Plants are not mosquitos of course, and their genetic differences seem to hold a different rank to those of animals, but DNA studies of these Dendrobium taxa could be useful. I think that I must be a splitter at heart, even though regarding Acrolophia, a genus with which I am now trying to get to grips, I feel that at least two of the currently accepted species should be sunk, one as a sub-species and one altogether. However, from your descriptions of the Dendrobium bigibbum/phalaenopsis complex, I would go for all 4 taxa as separate species at present, until it could be proved otherwise. Regards, greig russell "Valhalla", Osborne Lane, 7975 KOMMETJIE, Western Cape. (021) 783 3962 http://www.geocities.com/pennypoint9/ http://tygerorchids.itgo.com PASSION IS THE ONLY REASON _______________________________________________ the OrchidGuide Digest (OGD) [EMAIL PROTECTED] http://lists.orchidguide.com/mailman/listinfo/orchids
