12046[AZ] Re: 4ns and 2ns: Where We are Now : Change in Thinking
- Feb 2, 2009Bill
I respectively disagree with your position.
Here is the paper on line
Here is the conclusion
No diploid R. austrinum or R. atlanticum was found despite extensive
sampling of taxa from diverse sources and geographical origins (26 R.
austrinum and 30 R. atlanticum accessions collected throughout the
Southeast). The assessment of these species as diploids in previous
studies was based on a much more limited sampling (Ammal, 1950; Li,
1957; Sax, 1930). Therefore it seems unlikely that the lack of
diploid forms of R. atlanticum and R. austrinum in this survey
represents a sampling limitation, but rather a predominance of
polyploids in these species. This appears to be the case for R.
calendulaceum as well, where there are no reports (present study
included) of diploid populations.
Now yes Ranney did find that some things called austrinum were 2n and
3n but these are in my opinion and of the author are most likely not
austrinum had instead have been previously misidentified. The 2n
austrinmum came from the Biltmore Estate and the 3ns from the North
Carolina Arboretum. No plants thought to be austrinum in a native
population were anything but 4ns. The same was true of atlanticum.
Note: There were also some 4n flammeum not collected in the wild.
Note: But all of this has at least 3 major problems. One the
definition of species is not very precise. Two nature is not so
simple. Three and most importantly Ranney and Hall start by assuming
that species are as previously outlined and then go from there.
Despite these problems and the newness of the technigues employed it
is my position that the 3 findings outlined previously are simply too
supporting of one another to not be taken seriously.
Evidence is evidence and conclusions are just that conclusions and
you have every right to come to your own.
--- In email@example.com, "William C. Miller III" <bill@...>
> Regarding Ranney's findings: If you take another look at Jones,
> Lynch, and Krebs, you will note that Ranney (ARS, Vol 61, No. 4,Fall
> 2007, pp 220-227) found /austrinum/ to be 2n, 3n, and 4n usingflow
> cytometry. I think that's a significant finding given the relativewhat is
> small power of the sample size.
> If Hall selected a different sequence of the genome to evaluate,
> the possibility that an entirely different clade relationship mightbe
> sjperk5 wrote:
> > For many years the common belief, excluding canadense and vaseyi,
> > our native azaleas liked to cross with one another and producetime
> > fertile offspring.
> > What was interesting is R. calendulaceum a known 4n for a long
> > seemd to be able to produce fertile offspring in both directionswith
> > known 2ns. Now crossing 4ns and 2ns should usually producenonfertile
> > offspring but in native azaleas the literatures was full ofnorm.
> > documented cases of fertile offpring from such crosses being the
> > For years R. calendulaceum and R. austrinum have been crossed to
> > produce fertile hybrids. Dodd, Aromni, Sommerville, and many
> > have produced numerous beautiful hybrids using this combination.with
> > The theory was R. calendulaceum had some magicial powers to make
> > crosses with the 2n native azalea not result in nonfertile 3ns but
> > instead fully fertile 4ns. This magic power had something to do
> > R. calendulaceum being merely a 4n R. cumberlandense or a specialcounting
> > unreduced combination of R. cumberlandense and other native 2ns.
> > Three events changed the thinking. Ranney showed using new
> > technigues that austrinum and atlanticum where 4n. Hall showedthat
> > the 4ns and 2ns were at least in nature not crossing to any greatfinding
> > extend but instead formed distinct clades. Hybridizers of native
> > azaleas doing controlled crosses in the north and south were
> > that 4n X 2n were almost never successful and that 2n X 4n seemedto
> > usually produce infertile offspring.fact
> > Hall showed that R. cumberlandense and R. calenducaleum are in
> > not all that closely related. R. calenducaleum is more closelyand
> > related to luteum, austrinum, atlanticum, colemanii, canadense,
> > molle than to any of the memebrs of the 2n clade including R.seem to
> > cumberlandense.
> > So three different approaches to analyzing our native azaleas
> > have converged on instead of our native azaleas being one large2
> > interbreeding collection of species they are instead divided into
> > clades along basically ploidy lines that are reluctant to shareDNA
> > across multiple generations.
> > John Perkins
> > Salem, NH
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