Speciation. Was: Lycoris squamigera in bloom here in Maryland

Speciation. Was: Lycoris squamigera in bloom here in Maryland
J.E. Shields (Sat, 06 Aug 2005 10:15:25 PDT)

Hi Jim McK.,

I'm not a taxonomist, but I do read a bit in the field
occasionally. Sexual reproduction has never to my knowledge been one of
the criteria for a species. The aforementioned apomictic rain lilies are
not reproducing sexually, albeit they may use what appear to be
seeds. Reproductive isolation is the primary factor, even when it is
achieved by physical isolation -- across a mountain range, for
instance. Hybridization and reproductive isolation are both mechanisms for
speciation. Failure of sexual reproduction with other species is just one
way to make a species, but it should be sufficient.

If you want a hairy problem in "what is a species?" look at the
bacteria. They appear to occasionally exchange DNA quite promiscuously
with clearly unrelated bacteria. Otherwise they mainly reproduce
clonaly. I expect to see hierarchical taxonomic classifications of
bacteria replaced by phylogenetic trees based solely on DNA, with the
"species" being labelled with serial numbers instead of names. Indeed,
this seems a prime example of where the evolutionary unit is not the
species nor even the individual, but is the gene, a la Richard Dawkins' books.

Of course, with each generation of clonal reproduction, mutations can
occur, and these accumulate and are passed on from mother to daughters. So
there is genetic drift possible even in apomictic or sexually sterile
organisms.

Nature is truly marvelous to behold! There is seemingly no end to the
variations in ways to change organisms -- many don't work, of course. The
most amazing thing is that so many of them do occasionally work! They are
working all the time. The Hymenocallis are in a dynamic state, especially
the species in the southeastern USA. Their DNA makes them look almost like
a single species, I've heard. Twenty thousand years ago, there probably
was nothing in the present USA that could be called a Hymenocallis. They
returned out of Mexico and the Caribbean as the northern glaciers
retreated, and have been forming new species since then.

Regards,
Jim Shields

At 12:36 PM 8/6/2005 -0400, you wrote:

Jim Shields wrote: "Since L. squamigera is reproductively isolated from
other Lycoris species including, I presume, both its original parents..."

I'm just about sure you are right in saying that Lycoris squamigera is
reproductively isolated from other Lycoris; but the reason it is
reproductively isolated is that it does not reproduce sexually. Or
are there such things as sexually reproducing Lycoris squamigera?

I've always assumed it to be a clone.

I don't have a problem with species which arise via hybridization, as long
as they form sexually reproducing units. To me, that's just a nomenclatural
problem: the parental species in those cases are really themselves
conspecific, and the proof of that is the ease with which the purported
"hybrid" species forms a sexually reproducing unit.

This happens because "bad" botanists have given species rank names to
populations which, although they are different in appearance, are really no
more different than breeds of domesticated animals such as dogs.

Also, to my way of thinking, it makes no sense to call an entity which does
not reproduce sexually a species. If there is not a sexually reproducing
entity which corresponds to what we know as Lycoris squamigera, then it's
not a species.

Jim McKenney
Montgomery County, Maryland, USA, USDA zone 7, where I'm happy to have my
Lycoris reproduce any way at all.

-----Original Message-----
From: pbs-bounces@lists.ibiblio.org [mailto:pbs-bounces@lists.ibiblio.org]
On Behalf Of J.E. Shields
Sent: Saturday, August 06, 2005 10:48 AM
To: Pacific Bulb Society
Subject: Re: [pbs] Lycoris squamigera in bloom here in Maryland

Hi Jim McK, and all,

Get a copy of the Chinese paper (in English) on Lycoris species from Jim
Waddick, if Jim W. still has any left. Since the hybrid origin is not all
that clear (as far as I can recall -- wait for someone to do DNA) I suspect
that the only properly published name is squamigera.

In any case, it seems that new species arise by hybridization in
nature. Since L. squamigera is reproductively isolated from other Lycoris
species including, I presume, both its original parents, it is probably a
good species anyway. Hybrid origin per se would not disqualify it;
reticulate evolution in action. I think there are parthenogenic
(apomictic) species of Zephyranthes (rain lilies) that are considered good
species botanically.

I don't have bloom size squamigera planted here, but I have one scape each
showing on LL. sprengeri, chinensis, and longituba. More should be popping
up any day now.

Regards,
Jim Shields
in central Indiana (USA)

At 10:27 AM 8/6/2005 -0400, Jim McK. wrote:

Lycoris squamigera is starting to bloom now here in zone 7 Maryland.
........

Can anyone tell us what the correct name for this plant would be according
to the rules? I don't think we can use Lycoris squamigera, because it was
published as rank species. Does a combination exist for plants of the
parentage assumed for what we call Lycoris squamigera?

Jim McKenney

*************************************************
Jim Shields USDA Zone 5 Shields Gardens, Ltd.
P.O. Box 92 WWW: http://www.shieldsgardens.com/
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344 or toll-free 1-866-449-3344 in USA

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