Re: [Killietalk] Tank fish in the wild

[rscalf at jps_net]

>In a recent thread, wisely closed by the moderator, a particularly ill 
>informed comment was made.
>
>"For such reasons many of our aquarium fish could probably never make it 
>in the wild."

Could it be that we are still mucking our way through the Darwin vs Lamark view of evolution? 

Well more than a century after science became convinced that aquired traits are not inherited (unless they are coincident with a change to the genes, which is extremely rare) some people still have a Lamarkian edge to their world view.  I hear this even in conversations about humans. 

Per Darwin (and Mendel):  Seems to me that breeding fish in a tank could affect their genetic makeup by favoring those best adapted to survival in a tank. Let's say a species has fry whose mouth sizes run a certain range; That 30% can take bbs at hatching, 70% cannot.  If breeders feed bbs as first food, I'd bet you'd see a gradual increase in mouth size at hatching for this species. Perhap 30-70 might drift to to 75-25 after many generations. Perhaps it's possible that having a larger mouth might be maladaptive in the wild.....  but that doesn't seem likely.

Per Lamark: If fry survival from P1 to F1 and on is reasonably high, it's difficult to imagine that a population would evolve to being incompetent in the wild by merely being in a tank. That would imply that a species could aquire 'tank-ness'  which is different from 'wild-ness'  by somehow absorbing the essence of it's environment.

  Just my take on all of this. 

            Rusty Scalf
            Berkeley, CA







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