species and strains

David Fitch david.fitch at nyu.edu
Tue Jun 8 15:15:21 EST 1999

Just want to clarify a point of nomenclature about Caenorhabditis species
related to C. elegans that seemed generally problematic at the meeting, and
to make a general appeal--

There are 4 "sister species" of Caenorhabditis used in many comparisons.
Besides *C. elegans* and *C. briggsae*, there are:

1.  *C. remanei* (in some of the literature, previously referred to as "C.
vulgaris" or "vulgarensis" or "vulgariensis").  Strains include EM464,
EM546, SB146, VT733.

2.  *C. sp.* (as yet an undescribed species, previously and incorrectly
known as "C. remanei"--hence a great deal of confusion with the above
species).  The only strain available from the CGC is CB5161.

To avoid confusion, please use the STRAIN designations in all work.
Taxonomy will change, but strain designators will not.  Please see the WSRN
database for more info (including info on all non-elegans strains):

Although the relationships between these 4 Caenorhabditis sister species
are not yet clearly established, it is possible that CB5161 is less closely
related to C. elegans, C. remanei and C. briggsae than the latter 3 species
are to each other.

A fifth Caenorhabditis species (also undescribed) diverged more anciently.
The strain designation of this species (C. sp.) is PS1010.

To provide data for informative comparisons as well as to help resolve the
elegans-briggsae-remanei "trichotomy", I would like to encourage all who
are making such comparisons to obtain orthologous sequences from all 5 (or
at least the most closely related 4) Caenorhabditis species.  Only with
more data will this important phylogenetic problem be resolved.  Only with
a resolved phylogeny will certain functional comparisons make sense (e.g.,
establishing the statistical significance of coevolutionary correlations
requires a fully resolved phylogeny).

I would also like to encourage those with cDNA and genomic libraries of
these species to make them more generally available.

Thanks for the great meeting!
Best wishes,
Dave Fitch

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