Greetings & a happy new millennium to all Annelida members,
Phizzzzz, whooosh, kapowweee! There you go - imagine if you can some
virtual fireworks making sinuous wormy shapes in the sky in celebration of
the occasion. :^)
Now back to earth (& sea) with the progress of worm research. Damhnait
McHugh's latest paper is a nice wide-ranging review of the state of play
with the annelid molecules. Here's the cite and abstract.
McHugh, D. 2000. Molecular phylogeny of the Annelida. - Canadian
Journal of Zoology Revue Canadienne de Zoologie 78(11):1873-1884.
"Traditionally, the Annelida has been classified as a group comprising the
Polychaeta and the Clitellata. Recent phylogenetic analyses have led to
profound changes in the view that the Annelida, as traditionally formulated,
is a natural, monophyletic group. Both molecular and morphological
analyses support placement of the Siboglinidae (formerly the
Pogonophora) as a derived group within the Annelida; there is also
evidence, based on molecular analysis of the nuclear gene elongation
factor-1 alpha, that the unsegmented echiurids are derived annelids. While
monophyly of the Clitellata is well-supported by both molecular and
morphological analyses, there is no molecular evidence to support
monophyly of the polychaete annelids; the Clitellata fall within a
paraphyletic polychaete grade. Relationships among groups of polychaete
annelids have not yet been resolved by molecular analysis. Within the
Clitellata, paraphyly of the Oligochaeta was indicated in a phylogenetic
analysis of cytochrome c oxidase I, which supported a sister relationship
between the leeches, including an acanthobdellid and a branchiobdellid,
and two of the four oligochaetes in the analysis. There is some evidence
from analysis of 18S rRNA sequences for a sister-group relationship
between the clitellates and the taxon Aeolosoma. There is no agreement
regarding the body form of the basal annelid, and while molecular analyses
provide strong support for the Eutrochozoa, the identity of sister-group to
the Annelida among the Eutrochozoa remains enigmatic. It is
recommended that future investigations include additional conserved gene
sequences and expanded taxon sampling. It is likely that the most
productive approach to resolving annelid phylogeny, and thus increasing
our understanding of annelid evolution, will come from combined analyses
of several gene sequences.
--
Geoff Read <g.read at niwa.cri.nz>
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