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Polychaete molecular phylogeny

Geoff Read g.read at niwa.cri.nz
Thu Dec 16 22:25:20 EST 1999

Interested in this paper? Please contact Pat Hutchings, 
path at amsg.austmus.gov.au (PatH),  who will have available reprints of the 
following recently-published contribution to the annelid phylogeny debate.  

Note: Comment to the list are welcome, but  DO NOT SEND REPRINT  
REQUESTS to the list (or to me). Thanks, - GBR.

Brown, S., G. Rouse, P. Hutchings, & D. Colgan. 1999. Assessing the 
usefulness of histone H3, U2 snRNA and 28S rDNA in analyses of 
polychaete relationships. -- Australian Journal of Zoology, 47(5):499-516.  

"DNA sequence data from for histone H3 (34 species), U2 snRNA (34 
species) and two segments (D1 and D9-10 expansion regions) of 28S 
rDNA (28 and 26 species, respectively) have been collected to investigate 
the relationships of polychaetes. Representatives of all of the major 
morphologically identified clades were used, as well as members of the 
Sipuncula, Echiura, Turbellaria, Clitellata and Siboglinidae (formerly the 
phyla Pogonophora and Vestimentifera). Maximum parsimony analyses of 
the separate data sets gave conflicting results and none conformed closely 
to previous results based on morphology. Instead each data set provided 
corroboration of a few of the morphological groupings, usually pairing, 
though inconsistently, members of the same family. Higher groupings 
proposed on morphological grounds were rarely recovered. Maximum 
parsimony analysis of the combined data, excluding areas of uncertain 
alignment, recovered some morphological groupings such as Cirratulidae, 
Terebellidae, scale worms and eunicimorphs, and did not significantly 
contradict others. However, some expected groupings were not recovered. 
Surprisingly, the fanworms (Sabellidae and Serpulidae) were not shown as 
sister taxa, and monophyly of Phyllodocida, a morphologically well 
corroborated clade, required four more steps than most parsimonious 
trees. Aciculata was not seen in our analyses, although it was the most 
strongly supported large clade in Rouse and Fauchald (1997, Cladistics 
and polychaetes. Zoologica Scripta 26, 138-204). Trees constrained to 
show Aciculata as monophyletic were 18 steps longer than the most 
parsimonious trees. If trees are rooted on sipunculans rather than the 
nematode, Aciculata is nearly recovered, being rendered paraphyletic by 
the inclusion of the sister-pair of Oweniidae and Chaetopteridae. As 
suggested by some recent morphological and molecular analyses, 
Siboglinidae and Clitellata may well have sister groups among polychaetes. 
The morphologically aberrant Sternaspidae are closest to members of 
Terebellida in the present analyses, supporting the placement of Rouse and 
Fauchald. Interesting results deserving further assessment concern the  
placement of Chaetopteridae, Oweniidae and Sipuncula.   

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