Mr. Mushrooms said: "Hawaii, for example, is completely isolated from the continents and probably has had plenty of time for new mushroom species to occur. And yet they haven't. Plenty of other lifeforms have evolved there and Hawaii is a textbook case for allopatric speciation or the founder effect. How do you answer that?"
When you first mentioned the islands of Galapagos and Hawaii as being textbook cases for speciation, I assumed you were referring to the famous studies of how allopatric speciation has occurred within, and entirely within these archipelagos (disregarding the founding individuals). For example, studies of the adaptive radiation of Galapagos finches and the diversification of Hawaiian fruit flies have shown how geographically isolated populations inhabiting neighbouring islands have evolved into different species, under different selection pressures. I made the point that, in contrast to finches and fruit flies, mushroom populations living on neighbouring islands would not be significantly isolated.
I now understand that you were taking a broader view of these scenarios, and asking why islands such as these don?t have an endemic mycoflora, with reference to neighbouring continents.
My answer is that to some extent they do. However, I would argue that perhaps even in Hawaii, the most isolated group of islands, the extremely high dispersibility of mushroom spores is still the major factor affecting species distribution, acting to homogenize mycoflora on a hemisphere and even global scale. You say that "plenty of other lifeforms have evolved [in Hawaii]", but fail to consider that all of the examples you're thinking of are nowhere near as dispersable as mushrooms.
Having said this, I will backtrack a bit and concede that local speciation events are important - but if you look to isolated islands for evidence of this you will be disappointed. It is very likely that Hawaii, before European settlement, supported a more diverse endemic mycoflora, a small fraction of which persists today, having been outcompeted by introduced species. There is much convincing evidence to support this. Genetic analysis of some common Hawaiian mushroom species have shown that they are almost certainly recent, alien arrivals from overseas. The legislation that Mjshroomer cites prohibiting species importation is a response to what has already been a catastrophic reduction in the diversity of Hawaii?s endemics due to invasive species. Many ecology textbooks present Hawaii as a prime example of the susceptibility of long-isolated island ecosystems to invasion (I am talking about a 80-90% reduction in some major groups). So, the impoverished mycoflora of today?s Hawaii gives little clue to the diversity that may have existed several hundred years ago. The same holds true for other islands - in fact the fungal community may be the first to be replaced during invasion events.
Mr. Mushrooms also said: "My point was, and is, that the species line blurs. You should ask Lizard King about the widely varying macroscopic morphological differences in Psilocybe weilii to the point that a person would think they are picking a half a dozen different mushrooms. This is why we normally rely on the microscopic differences to differentiate between species. This is bluemeanie's whole point. He has been working on the various species from Australia for some time now."
Apart from making provisional identifications, I am really not interested in morphological species concepts for mushrooms, be they macro- or microscopic. They?re inconsistent. The relatively simple cellular organization of mushrooms serves poorly to record their evolutionary history. As I have explained, on the *genetic* level, mushroom species or lineages are readily differentiable and distinguishable, given sufficiently detailed analysis. (I do not mean that ?species? are always readily understandable according to a strict biological species concept, but instead that genetic analyses, combined with judiciously selected mating tests, provide a level of resolution that is much more useful than any BSC-constrained definition.) Field collectors or cultivators of psilocybes may not find genetic definitions of mushroom species very useful, but there?s no argument that species boundaries are usually and persistently blurred beyond our comprehension, just because microscopes and eyeballs cannot detect properties of genetic divergence.
Bluemeanie said: "any one have the means to conduct a compatibility / isozyme test/comparison? I had a guy in Canada doing it, but he hasnt replied for a while."
I can do better than isozymes (DNA sequence analysis + selective crossing tests), send me a message if you?re interested. Given the right material I could resolve relationships between your australian species without much difficulty - I'd be happy to take this on.
Teonan ? I agree completely with your critique of MJShroomer?s post. To me, MJShroomer seems to be an excellent morphological taxonomist.
Finally, to return to the original questions about speciation mechanisms, I?ve compiled a background reading list:
Ko, S.K., Young, Lim, W.K., Yang, H.K., and H.S. Jung (2001) Phylogeographic divergences of nuclear ITS sequences in Coprinus species sensu lato, MYCOLOGICAL RESEARCH 105(12) pp.1519-1526
[This Korean study, published in a British journal, gives an example of how the original locality of a speciation event may be determined for a globally-distributed species. It also quantifies ITS divergence and phylogeography within four coprinoid species, and shows how some types of DNA data give evidence for the existence of cryptic species]
Vilgalys, R. and B.L. Sun (1994) Ancient and recent patterns of geographic speciation in the oyster mushroom Pleurotus revealed by phylogenetic analysis of ribosomal DNA sequences, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES USA 91 pp4599-4603
[relationships between genetic divergence, reproductive isolation and biogeography are examined using sequence data in this study by America?s most prolific mushroom sequencer, Rytas Vilgalys]
Hibbett, D.S., Hansen, K. and M.J. Donoghue (1998) Phylogeny and biogeography of Lentinula inferred from an expanded rDNA dataset, MYCOLOGICAL RESEARCH 102 pp.1041-1049
Hibbett, D.S., Fukumasa-Nakai, Y., Tsuneda, A. & M.J. Donoghue (1995) Phylogenetic diversity in shiitake inferred from nuclear ribosomal species, MYCOLOGIA 87 pp618-638
[studies by Hibbett, a leading American evolutionary mycologist, which continue the molecular approach to studying mushroom speciation, with an emphasis on between-species relationships]
[The past decade has seen a proliferation of studies like this, which focus on different mushroom groups at different levels of resolution. Some ponder evolutionary questions relating to speciation mechanisms, but most are concerned primarily with relationships ? i.e. pure systematics. I will not bother to list these here but feel free to msg me if these are of interest]
Chase, T.E. and R.C. Ulrich (1990) MYCOLOGIA 82 pp.73-81 and 67-72
[studies of the mushroom species Heterobasidion annosum which suggest that reproductive isolation of mushroom populations may evolve rapidly through the action of just a few intersterility loci, which override mating compatibility]
Ramsdale, Mark, and Alan Rayner (1994) Distribution patterns in number of nuclei in conidia from heterokaryons of Heterobasidion annosum and their interpretation in terms of genomic conflict, NEW PHYTOLOGIST 128 pp123-134
Ramsdale, Mark, and Alan Rayner (1996) Imbalanced nuclear ratios, post-germination mortality and phenotype-genotype relationships in allopatrically-derived heeterokaryons of Heterobasidion annosum, NEW PHYTOLOGIST 133 pp303-319
[these two papers co-authored by the highly eccentric Rayner begin to present an original and thought-provoking way of understanding speciation (this is my interpretation rather than something explicitly stated) in terms of the dynamics of conflict and co-operation between potentially co-existing populations of nuclei]
hope these are of interest, if anyone?s managed to read this far 
(I think this will be my last post on this subject, as it?s an inappropriate forum - perhaps an email group or some other forum would be more suited ? contact me if you have any ideas) 
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