April 5, 2010

Ulrike Siebeck
Post Doctoral Fellow
School of Biomedical Science
University of Queensland
Sir Fred Schonell Dr
St Lucia QLD 4067

Dear Dr. Siebeck:
I have read a brief review (Secret Code, NATURE vol. 464 no. 7285 March 4, 2010 page 10) of your article (Curr. Biol. Doi:1016/j.cub.2009.12.047 (2010)) about damselfish.  You have shown that they can see by ultraviolet, and that this permits them to attack members of their own species that intrude into their territory without bothering to challenge members of other species.

Perhaps as a light chauvinist I overstate the case, but the included pictures of a couple of species of damselfish looked very similar.  I would suspect they compete for the same food and hide from the same predators. 

Why then would one attack a member of its own species but ignore a member of a different species?  What threat does a conspecific intruder bring that a heterospecific intruder does not?

Well if they are so alike, the only danger is that the intruder of the same species might bring in genes to contribute to the local gene pool.  That might increase local genetic diversity.  Were that a good thing, the intruder should be welcomed.  Indeed it will tend to crowd out the DNA or the defender, but this would be a trifling matter compared with the DNA competition from a different species seeking the same good stuff.

So based on your work alone, it would seem that increasing genetic diversity is a bad idea, an idea so bad that it is worth some risk to the fish to prevent it.

That may seem like a lot of theory to hang on a limited set of evidence gathered for a completely different purpose.  But there is an enormous amount of evidence to support this posted at nobabie.net, where I also put my thoughts and correspondence.  The March 25, 2010 posting, which is a poster I presented at a meeting of the American College of Medical Genetics in Albuquerque last month is probably the easiest access to most of the data. 

Let me know what you think.  It appears to me that this is a case where great attention to detail in a limited field produces results with implications far from the initial focus.  Alas, my own instinct is to look at the biggest possible picture.


M. Linton Herbert MD

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