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Synodontis 'fin clip' results
Posted: 06 Feb 2010, 02:51
by Dave Rinaldo
I sent clippings of these two fish to Jeremy J. Wright.
Here are his results.
jjwright wrote:Hi Dave,
Good news - the first molecular analysis finished up this morning! Better news (for me, anyway) - my preliminary IDs are supported by the results. Both of your samples shared a close sister relationship with S. njassae, with 100% posterior probability support (Bayesian phylogenetic reconstruction). This is based on a combined analysis of cytochrome b (mitochondrial) and ribosomal protein-coding gene S7 (nuclear) genetic data.
Best wishes,
Jeremy
Here's a thread discussing the fish in the first pic.
Re: Synodontis 'fin clip' results
Posted: 06 Feb 2010, 03:38
by Birger
Thanks for your PM Dave...This is good news for you, It will be interesting to see the rest of Jeremy's study...if or when released. This fish had us fooled.
Birger
Re: Synodontis 'fin clip' results
Posted: 06 Feb 2010, 11:54
by sidguppy
looking good!
I must say these have all the characteristics of a njassae except the pattern, but i guess there's a lot of variety in that
they do display the low elongated shape and the long straight downwards curve from the dorsal to the point of the snout
the hybrid mad scientists never get this straight; they're still fooling around with highbuild syno's that have huge adisposes, a bent or crooked line from dorsal to snoutpoint and huge blobby spots.
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 19:41
by Jools
Hi Dave,
Nice fish - did this come from the PVAS auction of 2008?
Jools
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:04
by Mike_Noren
Not to rain on anybody's parade, but the result as reported isn't conclusive. "Close sister-group relationship" to njassae presumably means that it was the fish most closely related to njassae included in the analysis, but without additional information it doesn't necessarily mean the same species - the result would be compatible with these fish being members of a different species closely related to njassae. Also, that the result is from a combined analysis of mitochondrial and nuclear analysis means that the fish can theoretically be a hybrid with njassae as one of the parent species (probably mother, as the cytb fragment is faster-evolving and therefore likely to overrule the nuclear S7 fragment in the analysis).
It is sometimes harder than one might think to identify animals to species with DNA data. Sometimes it's obvious, othertimes not, especially in groups where there aren't many already sequenced DNA sequences to compare with.
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:09
by Dave Rinaldo
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:13
by Jools
Indeed, I was also thinking that, to now, there isn't much other analysis of this type of the genus and so to start using it now is a little fraught.
I have a funny feeling about S. courteti.
Jools
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:15
by Jools
Both pics are the same fish? Anyway, the reason I ask is because of the Syno that I posted for ID elsewhere today reminded me of this fish and I know it was sold at the PVAS auction in 2008 and that you were there too.
Jools
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:28
by Dave Rinaldo
Jools wrote:
Both pics are the same fish?
Jools
Two different fish purchased at different times.
I forget how the first pic was labeled.
The second came labeled as
Re: Synodontis 'fin clip' results
Posted: 07 Feb 2010, 20:30
by Jools
OK, many thanks, that clears it up.
Jools
Re: Synodontis 'fin clip' results
Posted: 08 Feb 2010, 06:22
by racoll
Mike Noren wrote:Not to rain on anybody's parade, but the result as reported isn't conclusive. "Close sister-group relationship" to njassae presumably means that it was the fish most closely related to njassae included in the analysis, but without additional information it doesn't necessarily mean the same species - the result would be compatible with these fish being members of a different species closely related to njassae. Also, that the result is from a combined analysis of mitochondrial and nuclear analysis means that the fish can theoretically be a hybrid with njassae as one of the parent species (probably mother, as the cytb fragment is faster-evolving and therefore likely to overrule the nuclear S7 fragment in the analysis).
It is sometimes harder than one might think to identify animals to species with DNA data. Sometimes it's obvious, othertimes not, especially in groups where there aren't many already sequenced DNA sequences to compare with.
This was exactly my interpretation Mike.
The Bayesian analysis will tell us that the fish in question is more closely related to
S. njassae than anything else. This doesn't mean that it
is S. njassae or not, as two
S. njasse with identical DNA will still form a sister relationship, as will any
other species close to
S. njassae, but not in the dataset already.
Basically, what I saying is that it is hard to interpret branch lengths in a Bayesian tree, so I would be interested to know what the raw cytb
P-distance between the two specimens is.
