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[Annelida] Lab populations: Lessons from leeches

Geoff Read via annelida%40net.bio.net (by g.read At niwa.co.nz)
Wed Nov 1 20:17:10 EST 2006


There are some interesting results in this paper for those interested in
cryptic species and also peripherally alien invasives. The unnamed 
country referred to in the abstract might be the one south of Canada and 
north of Mexico, but that's just speculation on my part. :^)

Bely, Alexandra E. & Weisblat, David A. (2006)
Lessons from leeches: a call for DNA barcoding in the lab.
Evolution & Development 8 (6), 491-501.
doi: 10.1111/

Many evolution of development labs study organisms that must be
periodically collected from the wild. Whenever this is the case, there
is the risk that different field collections will recover genetically
different strains or cryptic species. Ignoring this potential for
genetic variation may introduce an uncontrolled source of experimental
variability, leading to confusion or misinterpretation of the results.
Leeches in the genus Helobdella have been a workhorse of annelid
developmental biology for 30 years. Nearly all early Helobdella research
was based on a single isolate, but in recent years isolates from
multiple field collections and multiple sites across the country have
been used. To assess the genetic distinctness of different isolates, we
obtained specimens from most Helobdella laboratory cultures currently or
recently in use and from some of their source field sites. From these
samples, we sequenced part of the mitochondrial gene cytochrome oxidase
I (COI). Sequence divergences and phylogenetic analyses reveal that,
collectively, the Helobdella development community has worked on five
distinct species from two major clades. Morphologically similar isolates
that were thought to represent the same species (H. robusta) actually
represent three species, two of which coexist at the same locality.
Another isolate represents part of a species complex (the "H.
triserialis" complex), and yet another is an invasive species (H.
europaea). We caution researchers similarly working on multiple
wild-collected isolates to preserve voucher specimens and to obtain from
these a molecular "barcode," such as a COI gene sequence, to reveal
genetic variation in animals used for research


For those interested in aliens the authors record Helobdella europaea
from North America for the first time (although despite the name it
could have originated in South America). Here's what the authors say:

"Consistent with its propensity to be dispersed by humans,
H. europaea was discovered in an artificial pond used
for holding various aquatic animals of diverse geographic origins
on the roof of a UC Berkeley laboratory building."

In the same issue:

Mitogenomics and phylogenomics reveal priapulid worms as extant models
of the ancestral Ecdysozoan

Bonnie L. Webster, Richard R. Copley, Ronald A. Jenner, Jacqueline A.
Mackenzie-Dodds, Sarah J. Bourlat, Omar Rota-Stabelli, D. T. J.
Littlewood, Maximilian J. Telford
Evolution & Development;
Volume 8, Issue 6, 2006Nov1, Page 502


   Geoff Read <g.read At niwa.co.nz>

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