>Why do certain fishes, for
> guard and protect fry that aren't theirs? They're related.
The fish that guards another parent's progeny may just not have any mechanism built into it that can overide the guarding behavior in the presence of eggs or fry. In other words, the guarding behavior is elicited by the stimulus of eggs or fry in a particular setting. This certainly explains why some other animals care for babies not their own (witness even cross-species nurturing in some mammals). Do you know of data that show that a fish parent is more likely to guard the progeny of close kin than of individuals from an altogether different population, but same species?
Of course, it is possible that the behavior is not overridden because in real life situations in nature, any eggs or fry encountered are likely to be closely related.
(of course, you have to believe in [Neo]Darwinian
> to begin with... but that's another matter).
I don't "believe in" evolution. Instead I accept the theory as the best available scientific explanation of the facts as known. That's the way science works. We don't have beliefs. We have conclusions. Of course, among the facts to be explained are such things as the fact that the kinds of fishes on earth today are quite different from the kinds that were on earth back in Silurian and Devonian times! Some consider theories something to be "believed in," like having faith. Oh, well. Better drop it, the lists managers prefer that we not discuss such matters.
David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email: dlmcneely-in-lunet.edu
telephone: (405) 466-6025; fax: 405) 466-3307
home page http://www.lunet.edu/mcneely/index.htm
"Where are we going?" "I don't know, are we there yet?"
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