GeoBio-CenterLMU Bericht 2008/2009 - Ludwig-Maximilians ...

downstream fragment appears to bear adequate resolution (Erpenbeck et al.
2006). Therefore, a concerted effort is now needed to evaluate the usefulness of
DNA signature sequences for poriferan species discovery and description, and
warrants comprehensive, phylum-wide coverage. Due to the fact that the highly
conserved COI-barcoding primers are prone to amplify sponge commensals
and/or symbionts, the primary task in the first phase of the project has been to
optimize sponge-specific primer design. Additionally, to resolve closely related
species, we will supplement the standard ca. 650 bp fragment with 440 bp of
downstream sequence. The addition of an unlinked marker such as either rDNA
ITS or the C2D2 region of the 28S rDNA gene might prove pivotal to accomplish
the project’s aims. The second task will then be, after sufficient initial data have
been gathered, to evaluate the potential of those DNA signature sequences
for species distinction, i.e. the error rate associated with certain thresholds of
genetic distances commonly used for species designation (see also Meyer and
Paulay 2005, Hickerson et al. 2006). It is imaginable that once a sufficiently
and densely covered reference system has been established and evaluated,
identification of any given specimen, using the standard barcoding marker, at
least to genus level should be possible. From there, species designation would
be contingent on more variable signature sequences such as rDNA ITS or a
fragment of the 28S rDNA. However, all this will take place in combination with
conventional comparative morphology. Therefore, we will focus the initial phase
of the SBP on appropriately identified and curated type specimens to build a
taxonomically sound and solid backbone for a DNA sequence aided taxonomy.
Samples will be obtained from associated partners e.g. the Queensland Muse-
um in Brisbane/Australia, which provides 17,000 sponge for extraction, funded
by the Marine Barcode of Life initiative (MarBol). All efforts will be undertaken
to support developing countries in their efforts to produce DNA barcodes from
specimens of their sponge fauna. Sequences and associated data (voucher
and taxonomic information) will be made publicly available at the project’s da-
tabase (see below) on its website (www.spongebarcoding.org) and submitted
to the Barcode of Life Data Systems and Genbank/EMBL databases. Such a
system could also enable a “reverse” taxonomic system, in that in large-scale
biodiversity surveys, all collected samples are genotyped for DNA signature
sequences, followed by pooling all specimens with identical or highly similar
sequences. This will enable focused morphological work on distinct genetic
lineages.
The Sponge Barcoding Website (www.spongebarcoding.org)
The Sponge Barcoding Database (SBD) is developed with the aim to function
as the primary access point for DNA signature sequences together with provi-
ding information on conventional morphological taxonomic characters to aid
Kurzbericht
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