Species -- forms -- sports
- Subject: Species -- forms -- sports
- From: "Andrew Lietzow" <email@example.com>
- Date: Tue, 27 Jul 2004 19:10:08 -0500
RE:>>As you have pointed out, the variegated forms had to be sports of the species.
George -- I believe you were talking to Ben when you stated the above. Did you mean to say "hybrids of the species" or "sports of the species"? I want to get this right.
To George, Ben, Bill, and interested parties,
What is at issue for me are these terms--- "Species", "Form" and "Sport".
#1 - Species. There are several acceptable definitions but for the sake of the thread that started out as "Rules of thumb for Hybridizing Hosta" I am focused on two methods for arriving at a reasonably acceptable definition of what, in hypothesis, constitutes a "species" organism.
The first definition of species is used by biologists who utilize numerical taxonomy, attempting to classify organisms based on overall similarity through examination of morphological, visible traits. The technical term for this method, I believe, is phenetics. A taxonomist has the luxury, responsibility, and highly challenging task of classifying organisms into phyla, i.e. phylogenetically,. through numerical taxonomy.
The second definition of species is used by biologists who utilize cladistics, or phylogenetic systematics, attempting to classify organisms based on their evolutionary relationships. I don't know that people who subscribe to this technique are taxonomists but may be evolutionary geneticists. I think it likely that those who utilize isozyme extraction and electrophoresis, and the interpretation of the resulting banding patterns fall into this group. In addition, those, like Ben Z., who utilize DNA weighting as a primary taxonomic criterion may fall into this group.
The point is that it's important to be able to reach a consesus as to what constitutes a species with historically important tools, yet the time may be upon us soon that we are able to analyze mitochondrial DNA and build maps of plants that support or refute a plant being a cladistic species.
#2 - Form -- Are forms of species equal to sports of species? Why or why not?
#3 - Sport - There has been no introduction of new genetic material and the DNA weight shuld be very similar (there could be some small reduction due to the mutation, but there could be no increase). Sports can exist for both hybrids and species, but I personally would prefer to call a species mutation a "form" and a hybrid mutation a "sport".
Once I have these terms understood, then I'll move back to the question of a yellow ventricosa. Wouldn't it be great if the nomenclatiure were a little easier.
BTW, George, I have been enjoying the phrase "loculicidally dihescent". Very cool.
Ciao. Gotta go watch the convention!
I am thinking that my hangup is on the use of the term "form".
From: "W. George Schmid" <firstname.lastname@example.org>
Sent: Tuesday, July 27, 2004 3:57 PM
Subject: Re: [hostapix] Computer mistake
I apologize. This seems to be an e-mail mix-up. You apparently sent a copy of Andrew's e-mail, which I got later and if you inspect the copy as I got it below you will see how your signature might be taken for the originator of the entire e-mail. I promise I'll take lessons in reading e-mails. I assumed that you were the sender since it was undersigned by you.
Both you and I agree that there are no yellow species, period! In fact I know of no yellow sport. Fagerlind thoroughly examined a population of H. ventricosa and determined it to be apomictic. That does not rule out a sport, of course, but I have never seen one. I have grown this species since 1957 and have never seen it sport to yellow. To start with I had several sources (England, Germany and the US) and none of these ever produced a variegated or yellow seedlings even though I have tried. It also never produced a variegated or yellow offspring left alone and open pollinated. Its cultivar 'Auremaculata' however does produce all kinds of variegated and viridescent yellow seedlings and that is what I am referring to in my book. As you have pointed out, the variegated forms had to be sports of the species. The first time they were described was in the late 1860s by von Siebold and Miquel and they seem to be very stable because they have not changed significantly in culture for the last almost 150 years. They had to come from some sporting event judging by total DNA.
I am sending you a copy of the e-mail below to explain my hasty earlier reply. George
It came in:
Date sent: 27 Jul 2004 02:04:05 -0000
As usually is the case, vastly important to any scientific discussion is agreement on the meaning of the terms. Taxonomists have successfully divided, or joined, populations of organisms into morphologically derived species for quite some time. Of course, we're looking forward to a DNA mapped
definition, but what do you use as the best definition of a Hosta species?
> For example, H. ventricosa exists in at least three forms, all supposedly of the same species. The DNA weight of Ventricosa Stearn 4x is 39.4, v. Aureomarginata, 39.2, and Aureomaculata 38.9. These are all very close DNA weights, thus highly unlikely to be hybrids. So would these "forms" be
Yes They can be considered as old sports of the plain green one
> Do "forms" of species plants yield true to type plants when selfed,
or would v. Aureomarginata and v. Aureomaculata yield all ventricosa (Stearns 31b) forms?
Mostly true ventricosa but those of V maculata can be yellowish
> If a yellow edge can be a form of ventricosa, why not an entire gold plant?
Obviously, the synthesizing sequence exists in the genome to produce the
carotenoids in the edge, so I'm trying to understand why a gold form MUST be a hybrid.
No good yellow ventrico as a yet as a mutation to plain yellow is
very rare That is why I can say that all yello seedlings from species
> It does seem, however, that if a ventricosa was going to mutate to a gold
form, it certainly would have done so by now, lots of times. It might even be readily available (as are most forms of species plants). We'd see whole populations of it in its native China and N-Korea habitat.
> So far, Bill Meyer's reference to a gold seedling is the first instance
I have heard of a gold version yet W. George states,
"Several variegated and yellow forms exist" on page 116, right column, end of 1st paragraph. Are these guys holding out on us, hiding these in the hills of the Appalachians and not letting us see them?
He too names yellow hybrids species
> Anyone own a gold form of ventricosa, that stays yellow all season?
I like to measure one to be sure it is not a hybrid with another
Institute of Biology,Leiden University, Clusius lab
Wassenaarse weg 64, 2333 AL Leiden, The Netherlands
Fax: +31-71-5274999. min temp -10C (15F)
W. George Schmid
Hosta Hill - Tucker Georgia USA
Zone 7a - 1188 feet AMSL
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