Speciation. Was: Lycoris squamigera in bloom here in Maryland

J.E. Shields jshields@indy.net
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 

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.

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.
>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
>pbs mailing list
>pbs mailing list

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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