Re: Genetic Analysis Of Coelacanths

[Aidan Karley <aidan_karley@yahoo.co.uk>]

In article <Pine.GSO.4.10.10506202229040.7641-100000@asuwlink.uwyo.edu>, 
Richard W. Travsky wrote:
> Since then, most coelacanths have been found along the east coast of
> Africa as far north as Kenya, with a concentration around the Comoro
> Islands, northwest of Madagascar.
>
       This makes me suspicious of the quality of reportage to start with. 
No mention of the Indonesian population [Nature, v395, p335, 1998] makes me 
think "hack job reporter" ... OK, later they mention the Indonesian 
population, but it's a strange way of sidelining a population that increases 
your target organism's range by a factor of 4+. 
       
> A genetic analysis of 47 coelacanths by German researchers shows, however,
> that the fish are probably all part of a single inbreeding population.
>
       I always get worried about this sort of report. By all accounts, 
Latimeria is a pretty rare tetrapod, so unless they've got pretty careful 
capture-sample-release, they could be directly or indirectly causing a 
substantial increase in fishing pressure on the population.
       
> found almost no genetic variation
> among the specimens. (By comparison, the researchers found a much greater
> variation between these coelacanths and the only other known living
> species, which was discovered in the late 1990's in Indonesia.)
>
       Now that's odd. Could that indicate a recent population bottleneck 
for the Comoro-area specimens? (There's an implication that they've sampled 
in the Comoro area, with limited access to Indonesian specimens; but it's 
not clear from what's quoted. Does anyone have a PDF of the Nature article?) 
The obvious missing datum is the within-group variation in the Indonesian 
specimens, so I'm wondering if they got 2 samples from Indonesia?
       This would be a fair argument that the Indonesian and East African 
populations actually represent different sub-species if not separate 
species. I know there was some controversy over some blood-type evidence 
(haemoglobin gene sequences?) about the Indonesian specimens a couple of 
years back, which aired arguments over whether there is one or two species. 
       
-- 
 Aidan Karley,
 Aberdeen, Scotland,
 Location: 57°10' N,  02°09'  W (sub-tropical Aberdeen), 0.021233
 Written at Tue, 21 Jun 2005 08:47 +0100



        
        
                
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