"Rob Halgren" wrote in message
...
Al wrote:

"Orchids that have been bred in captivity for generations grow better in
pots than wild ones." That's quote but not mine. :-) Smart breeders do
not use plants for breeding if they are prone to disease, so one would
think
that domestic populations that are generations old might be more disease
resistant. On the other hand, the environment we provide for them is so
protected that one would also thing they would not live long if some well
meaning person were to repatriate them into their native habitat.

I'll bet you get lots of replies to this topic.



I'll bite...

Are there any good examples of orchids where the same species in
cultivation


tends to be quite different in some significant way from its wild
counterpart?


Virtually all of them... Any cattleya which has been in
captivity for more than a couple generations is quite different from its
wild cousins. If nothing else, many breeders have intentionally
converted them to tetraploid. Line bred Phal 'aphrodite' (quotes mine,
because it is likely that the line bred ones have some hybrid
background) are very distinct from wild ones. Doritis pulcherrima is
quite cute in its native form, but you couldn't get one awarded today,
as the line bred ones have flowers that are several times bigger.
There is some debate in judging circles as to whether this is 'fair'.
No, it isn't fair if you are a wonderful wild collected flower and
competing against a line bred specimen. Sorry. But we don't grow
orchids to be fair, we grow them for nice flowers.

Why is line breeding so different than nature's breeding? Human
selection is different than natural selection. For example, if we see
an albino flower (and like it) we 'fix' the phenotype. Orchids are
designed to cross pollinate, not self pollinate. So, since you get a
copy of each gene (allele) from your parents, the albinistic allele can
be masked or diluted by the normal allele from the other parent. But
humans are persistant, and we will self that albino flower to try to get
offspring which are homozygous for the albinistic allele. Once we do
that, the phenotype is 'fixed'. In other words, if we self that albino
offspring, we can only get albino offspring. Natural selection would
have diluted that trait in the gene pool, since the vast majority of
potential mates have the gene for 'normal' color.

Anyway, we can do that for any trait. The human selection process
is actively directed, natural selection is not. This is why we have
terriers and St. Bernards - somebody wanted little dogs and somebody
else wanted big dogs, and selected appropriately. We've been mucking
about with everything for a long time. I bet you've never seen the wild
maize that our modern maize is bred from, and if you did you probably
wouldn't recognize it. Orchid breeders select for features they like
(vigor is certainly one of those), and don't breed with plants which
have 'inferior' features. One of the features that we absolutely must
select for is growth in captivity. If the plant can't grow from seed to
bloom, it can't be bred with. So we have no choice but to select for
plants that grow well in flask and pots. Wild collected plants are
often difficult to get 'viable' seed (seed that grows in flasks, anyway)
from, but once you get to the next generation, it is almost always much
easier.

Anyway, don't buy jungle collected plants. They are of absolutely
no use to the hobby orchid grower. They will not be 'better' (whatever
that means) than domesticated ones. That is not to say that they aren't
valuable from a genetic diversity standpoint. If you have bred all the
color out of your captive plants, you can't get it back unless you have
a wild plant which has the alleles for it. Line breeding is a one way
street.

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit

There was an interesting comment in the Nova (PBS) program about how line
breeding in dogs makes them more susceptible to viruses and cancers,
something I've always heard, but never understood. Anyway, your comment and
one by Peter O'Byrne about how line breeding and hybrid lines in what are
supposedly species makes me wonder.

How identical *is* species DNA anyway?

Is the genome like a template? If one could put the entire DNA strands of a
species on an overhead projector acetate, could one overlay all the G-C and
A-T base pairs on top of one another would they all line up? Could you say
that any variation within that line-up would be something like 'different
colored eyes, and so same species' or 'different all together and so a
hybrid'? I mean, how can one isolate individual variation within a
species? And how would one know that the aberrant base pairs weren't
individual variation but the result of hybridization?

Who is to say what species DNA is? Lord knows there's enough bickering and
infighting amongst taxonomists who classify species according to set
international rules. Who would be the agency that would determine and stamp
approve what 'species DNA' looks like? And how would they know? What if
they missed a few individuals? Like if a Greater Alien Space Race came to
the Earth they'd think by preponderance of numbers that the human species
was Asian, and take that DNA as criteria of human-ness. The tiny Bushman
from the Kalihari Desert would be shit out of luck because they don't look
Asian. What then? Would The Aliens be justified in eating Bushmen because,
according to their definition of human-ness, they weren't human?

K Barrett