livshultz at ansp.org
Wed Feb 4 11:04:54 CST 2009
I know the conversation has moved on but I just spotted the email below and since we are in the spirit of correcting errors . . . .
Asclepiadaceae as first circumscribed by Robert Brown and maintained by most botanists over the past ca. 200 years are also either para- or polyphyletic. See:
Livshultz, T., D. J. Middleton, M. E. Endress, and J. K. Williams. 2007.
Phylogeny of Apocynoideae (Apocynaceae) and the APSA clade.
Annals of the Missouri Botanical Garden. 94: 324-359.
(pdf available upon request.)
And Apocynaceae sensu lato is more practical in many ways. For a field botanist it is often easier to determine that a sterile or fruiting plant or an isolated seed is Apocynaceae s.l. than to figure out if it is Apocynaceae s.s. vs. Asclepiadaceae.
You are correct that there are two paraphyletic subfamilies, Rauvolfioideae and Apocynoideae, maintained in the current classification. In my research on evolution within the family, the entities I'm concerned with are the tribes of Rauvolfioideae and Apocynoideae, and their relationships to each other and to the three subfamilies that represent the former Asclepiadaceae. These tribes are, for the most part, monophyletic. My preferred solution to the paraphyly at the subfamily level is to elevate most of the tribes, or clades of 2-3 tribes, to subfamilies. This would result in ca. 20 subfamilies instead of 5, but subfamilies are for specialists (at least in botany). As a professor of college-level plant systematics, I only ever taught my students subfamilies for two families (Fabaceae and Rosaceae). And there is no reason that you have to teach all the subfamilies within a family.
Dr. Tatyana Livshultz | Curator of Botany
The Academy of Natural Sciences of Philadelphia | 1900 Benjamin Franklin Parkway | Philadelphia, PA 19103-1101 | U.S.A.
(215) 299-1051 | FAX (215) 299-1028
livshultz at ansp.org | www.ansp.org/research/biodiv/botany
>>> Kenneth Kinman <kennethkinman at webtv.net> 1/29/2009 2:07 PM >>>
Dr. Civeyrel is certainly correct, that sinking Asclepiadaceae
into a Apocynaceae (sensu lato) didn't really resolve the paraphyly
"problem" (which they felt "obliged" to correct). It just shifted the
paraphyly down to subfamily level. If their goal was to eliminate
paraphyly, they should have also split up the paraphyletic subfamilies
which made up Apocynaceae (sensu stricto) into more subfamilies.
As I said in my post last night, if you are going to allow
paraphyly, it would be much simpler to have a paraphyletic mother taxon
(Apocyanaceae sensu stricto) giving rise to a daughter taxon
(Asclepiadaceae). However, as long as strict cladism is the rage,
people are going to continue attacking paraphyletic taxa whether it is
helpful or not. With Takhtajan having also lumped these two families
together, fighting this move seems even more hopeless.
If you sink Asclepiadaceae in Apocynaceae, how come you can still have a
monophyletic Asclepiadaceae. At the most it would be monophyletic
Asclepiadoideae within monophyletic Apocynaceae. That is the intention
as well as the solution.
----- Original Message -----
From: "L. CIVEYREL" <civeyrel at cict.fr>
To: "Gurcharan Singh-satyam" <singhg at satyam.net.in>
Sent: Thursday, January 29, 2009 2:51 PM
Subject: Re: [Taxacom] [tdwg] Semantic Web: What is a species?
I am one of the researchers who worked on Asclepiadaceae and sadly from
my molecular results I was obliged to sink Asclepiadaceae within
Apocynaceae, but this resolve nothing.
Allright you have now a monophyletic Apocynaceae instead of a
paraphylectic Apocynaceae s. str., and a "more or less" monophyletic
But none of the subfamilies used for Apocynaceae are monophyletics (the
asclep sub fam are) and still they are used as valid subfamilies.
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