A paper on Siboglinid phylogeny just came out in Biological Bulletin. I
mention it to the Annelid list because Siboglinids are a good case where
morphology and molecules agree. A recent paper by Greg Rouse using a
morphological cladistic analysis and the paper by Halanych et al. (using
16S rDNA and 18S rDNA) reach similar conclusions.
A pdf for the Halanych et al. paper is available from Biological Bulletin, or I
can be contacted at the address below for reprints.
Halanych, K. M., R. A. Feldman, and R. C. Vrijenhoek. 2001. Molecular
evidence that Sclerolinum brattstromi is closely related to vestimentiferans,
not frenulate pogonophorans (Siboglinidae, Annelida). Biol. Bull. 201:65-
75.
Rouse, G. 2001. A cladistic analysis of Siboglinidae Caullery, 1914
(Polychaeta, Annelida): formerly the phyla Pogonophora and
Vestimentifera. Zoological Journal of the Linnean Society 132(1):55-80
Ken
Abstract. Siboglinids, previously referred to as pogonophorans, have
typically been divided into two groups, frenulates and vestimentiferans.
Adults of these marine protostome worms lack a functional gut and harbor
endosymbiotic bacteria. Frenulates usually live in deep sedimented
reducing environments, and vestimentiferans inhabit hydrothermal vents
and sulfide-rich hydrocarbon seeps. Taxonomic literature has often treated
frenulates and vestimentiferans as sister taxa. Sclerolinum has traditionally
been thought to be a basal siboglinid that was originally regarded as a
frenulate and later as a third lineage of siboglinids, Monilifera. Evidence
from the 18S nuclear rDNA gene and the 16S mitochondrial rDNA gene
presented here shows that Sclerolinum is the sister clade to
vestimentiferans despite lacking the characteristic morphology (i.e., a
vestimentum). The rDNA data confirm the contention that Sclerolinum is
different from frenulates, and further supports the idea that siboglinid
evolution has been driven by a trend toward increased habitat
specialization. The evidence now available indicates that vestimentiferans
lack the molecular diversity expected of a group that has been argued to
have Silurian or possibly Cambrian origins.
************************************
Kenneth M. Halanych
Biology Department
MS 33
Woods Hole Oceanographic Institution
Woods Hole, MA 02543
http://www.whoi.edu/science/B/people/khalanych/kmhpage.html
Phone: (508) 289-3565
Fax: (508) 457-2134
<khalanych at whoi.edu>
************************************
-- ANNELIDA LIST
Discuss = <annelida at net.bio.net> = talk to all members
Server = <biosci-server at net.bio.net> = un/subscribes
Archives = http://www.bio.net/hypermail/annelida/
Resources = http://www.annelida.net/
--
