Hello Greig. Apologies for spelling your name wrong in my last posting.
Some of the assumptions you used as a basis for your arguments in your posting (OGD V6 #365) are very familiar to anyone who has followed Mark Clements' and David Jones' work on Australian orchids. The problem is, they are largely unproven. Let's have a look at them: 1) Pollinators. You said: "Are they all using the same pollinator?" and "As for the smaller flowered compactum, one can assume that they are utilising a smaller species of insect to effect pollination. The pollinators are always important " It is generally assumed that each orchid species has only one insect species acting as a pollinator. While this has been shown to be true for a handful of terrestrial orchids and a smaller number of epiphytes, there is no reason to suppose it is always true. Those orchids where the "one insect" hypothesis has been validated are, without exception (I think ... I'm sure someone will tell if I'm wrong) those species that have really weird insect-attractant mechanisms, eg involving pseudocopulation or collection of pheronomes, etc. One species of carpenter bee is known to cause pollination of several species of large-flowered tropical Asian orchids (both species and hybrids). Males fruitflies of several Bactrocera species are known to be attracted to the flowers of Bulbophyllum patens ... the orchid must produce 2 different attractants since these fruitfly species are not all attracted by the same substances (Tan & Nishida in J. Chem. Ecol., 26,2:533-546 (2000). Things do not look good for the "one orchid species, one insect species" hypothesis. Consequently, my response to your question "Are they all using the same pollinator?" would have to be "so what if they aren't ?" 2) Allopatry. You said: "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? ". That doesn't follow, either. In the last 5 years I have found more than 12 examples of orchid species, supposedly "endemic" to New Guinea, growing quite happily in Sulawesi. The distance between these islands is considerable, but the orchids have crossed it. Last year I showed that Entomophobia kinabaluensis, supposedly a narrow-band endemic confined to Mount Kinabalu in north Borneo, is widespread and common in the Central Sulawesi mountains. The species is probably native to Sulawesi that has colonised a solitary outpost in Borneo ... but how did it get there ? Several years ago I found many specimens of a Thrixspermum, supposedly native to Vietnam and Taiwan, growing on a mountaintop in Malaysia.... that is really moving around. Six weeks ago I found specimens of what appears to be Chinese-Himalayan Cheirostylis species flowering happily in Sulawesi .... ie, thousands of kilometers from "home". Geographic separation is not the barrier we assume it to be. True, the New Guinea-form and the Timor Laut-form cannot share their DNA directly. But their seeds can possibly cross the gap and grow on the other side ... then the DNA will mix freely. 3) DNA studies. You said: "DNA studies are now showing that some "species" of mosquitos in fact comprise four genetically, absolutely distinct species". DNA studies on orchids tend to point in the other direction. At species level, it is often difficult to find any consistently-reliable genetic differences at all. At generic level, all the indications are that we'll end up with fewer, larger genera by the time the molecular biologists have finished. Finally, something that is not an assumption. You said: "I see your insistence that there be two consistently different characters as a bit limiting." It isn't mine. It is the taxonomic standard for botany. Traditionally, one difference results in a rank of "variety" or "subspecies" (I grieve that these sometimes-useful subspecific ranks are now outlawed by those who write the rules), while 2 differences are required for a species. If you want to challenge this, you'll have to take on some very influential people.... far more influential than lil' ol' me. Cheers, Peter O'Byrne Singapore _______________________________________________ the OrchidGuide Digest (OGD) [EMAIL PROTECTED] http://lists.orchidguide.com/mailman/listinfo/orchids
