Bangaii photo

[roguemonk]

Can I get on the wait list for some of the fry when their "weaned", if you do raise them?

I could probably take them as fry and raise them myself (I have lots of cultured copepods).

:-)

Brad

["Umm, fish?"]

Of course, but oh man! Knock on wood somewhere if you would, please! It's right after people talk about wanting babies that the male tends to swallow them....

[roguemonk]

Consider the wood knocked. :-)

Brad

[Linkia]

Will keep you in mind. Did you read the article (can't remember which one right now) that said additional males will pick up extra eggs in the wild? So if you have an extra male you could even have 4 males carrying at once in your tank. My theory on the reason yours get along is because of your surplus of food. Amazing what 10 extra feeding a day will do to a tank huh.

["Umm, fish?"]

I never heard that. That's crazy. I wonder what the evolutionary story on that is. (I'm not a big fan of evolutionary stories, a la selfish gene theories, as they never really make sense to me. It seems to me that a lot of animals do things that can't be easily summed up in some kind of probabalistic, advantage to the DNA kind of story. But I digress.)

My theory on the reason yours get along is because of your surplus of food.

Yeah, but aren't most people who are conditioning to breed over-feeding their fish? Maybe they just aren't going over the top enough? Gotta feed to breed.

I still see some aggression, but it's not even every day. I think it really helps, too, that they can all have places where they can't see each other. That said, I'm separating them when I get the chance. Well, maybe.... I need to get back to work, but I'll expand on that later.

[roguemonk]

Mutation produces variation, selection just picks from what's available, and the advantage is rarely absolute, mainly it's incremental. Altruism is a part of every species' makeup, just in varying degrees (more so in those that DON'T generally eat their own young)... Picking up the eggs may help to increase the size of the local school which may help everyone in the school survive at a higher rate, for example. And, if everyone in the school is loosely related (cousins and second cousins), then most of the males and females in the school have the same genes, so they're sort of "evolutionary communists" increasing their own representation in the gene pool by increasing that of their siblings and cousins. So carrying someone else's eggs (when you don't have any of your own anyway) may actually give your genes a better shot at increasing their representation in the next generation.

Certainly, in general, the imperatives are different for species that reproduce by the hundreds than those that reproduce one at a time. :-)

Brad (I'm not an evolutionary biologist, but I did stay at a Holiday Inn Express last night)

["Umm, fish?"]

Yeah, see that's my problem with genetic natural history stories. They all sound plausible (even competing stories), and not a single one of them is actually scientific (can't prove, can't disprove, can't even design a test).

On second thought, not all of them even sound plausible. (Not yours, Brad. Yours sounds pretty reasonable.)

So, your telling me that the cardinalfish's _genes_ know that it's related to most of the other cardinalfish around? Hmm.

[roguemonk]

Genes don't know. Natural Selection is truly results oriented. If the actions of a being with an "altruistic" gene makeup add to the survivability of his own or closely-related genes, then those genes will proliferate. In the case of fish, if a particular population is able to produce more offspring than nearby populations because its members are predisposed by their genes to pick up extra eggs when they don't have any of their own, then the next generation of the species will have a larger representation of those genes that predispose the fish to take on extra eggs, and a smaller representation (as a percentage) of the genes of more selfish fish that won't raise anyone else's eggs. And the next generation, the representation of the altruistic genes will increase, and so on, until perhaps the entire species bears the genes related to the predisposition.

A note on "just so" stories: They are seized upon by opponents of evolutionary theory as representing holes in the theory, since they cannot be proved. But they do not exist to bolster the theory (clearly only actual observed evidence can do this), but to rebut the objections that sceptics raise against the theory: that no one knows how certain transitions happened (thus they must have happened by some other process, aka a Miracle).

We can't always (barring the invention of a time machine or recovery of fossil evidence that, because of sampling, we may never be likely to find) go back and discover the fine details of the full story of how certain traits arose, how certain speciation events happened, or how certain stages in chemical evolution took place. That is not a scientific criticism of the theory, because a theory does not have to explain all events, but has to be the best explanation of all events by scientific method in order to be accepted. (A quick example: we can't analyze supernovae that exploded before recorded history, but that does not invalidate the theories constructed about the life cycles of stars that were made on the basis of more recent observations that have been made over far less than the span of almost any single star's life span.) But when that criticism is offered: "It is impossible for mutation and natural selection to explain the altruism of some male Banggai Cardinalfish who will take on eggs fertiliized by other males", it is only fair to accept that any plausible explanation is sufficient to rebut it. In other words, my scenario is not intended to explain the altruism of Banggai Cardinalfish (although it might :-)), but to rebut the allegation that mutation and natural selection can't account for it. Clearly, they can, even if this scenario doesn't represent the real sequence of events that produced their altruism.

To put it briefly, "just so" stories are not meant to fill out natural history, but to rebut unfair and unscientific criticisms of the theory of evolution. Those who use them to attack the theory of evolution are being doubly dishonest, because they don't have a better scientific explanation to offer, and they are making arguments from silence rather than attacking the observed evidence that overwhelmingly supports the theory.

Thanks,

Brad