AR: Species ancestry
WARNING: This is gonna get technical. You may want to hit that DELETE key, or
just file the following for future reference.
Tom Tadfor Little wrote:
: arilbreds descend rather directly from C.G. White's first fertile
: amphidiploids, which were mostly of unknown parentage. They are classified
: OGB rather than OB in recognition of the fact that we really don't know
: which arils might be present somewhere in their ancestry.
True! The classification system that established the OB & OGB codes followed
the "one-drop" rule. We don't know WHICH arils were ancestors to each of C.G.
White fertile amphidiploids, but we do know that he used regelia species in
developing them. Although they don't display many regelia traits, every one of
C.G.White's fertile amphidiploids that I've examined had the tell-tale hairs at
the base of the midribs on the inside of the standards -- a clear indicator of
: There is probably
: some regelia in them, but nowhere near half--more likely a few bits that
: made their way into the oncocyclus genome through crossover.
There has been speculation that the compatibility of oncos and regelias is such
that some individuals chromosomes may function as if they are homologous, even
though the complete sets are not. There are a few halfbreds, like ARDRUN, which
have been determined to have a complete set of regelia chromosomes (in this
case, I. korolkowii v. violacea), a complete set of onco chromosomes (I.
barnumae subsp. mariae) and two sets of TB chromosomes (species origin unknown).
What happens in advanced generations is still a matter of conjecture but my
opinions, after some 20 years of working with such lines:
1. A full set of regelia chromosomes? Highly unlikely.
2. One or more regelia chromosomes? Quite possible.
3. Regelia genes incorporated via crossover. Also possible.
No easy answers, but many intriguing possibilities -- and what an interesting
Sharon McAllister (firstname.lastname@example.org)
Cleaning up computer files while waiting for a VERY special seedling to open