Random Question About Genetic Traits

[ZeeJustin]

I was reading the thread entitled "How can gayness have a genetic basis?" and it got me to thinking...

Are there "cases" of genetic traits that are not desirable for reproduction that pass on anyway, and with "reason" (or perhaps I should say non-randomness)?

Let's call it a "Martyr Gene". A tribe needs a martyr to survive, but the martyr would not live long enough to reproduce. Naturally, he wouldn't pass on the gene.

HOWEVER, if instead his mother had a gene that said, "If I have a baby, there is a 1/100 chance he will be a martyr", then that mother's tribe will have a greater chance of surviving, assuming of course the martyr is able to sacrifice himself in a way that is beneficial to the society.

I'm not trying to make a point with this. Maybe it's an extremely elementary question, and if it is, I apologize, but I would really appreciate it if someone could indulge me and link me to a study or two.

[Leaky Eye]

By not desirable do you mean harmful to reproductive success, or just not helpful?

A trait does not have to make its host more fit, it just has to be fit within its host. A trait that actively makes its host less fit has a hard time.

As for your martyr scenario, I do not believe selection can occur in that fashion. Genetic traits that are helpful to societal productivity exist because they also directly help the carrier. In a society that has a certain concentration of cooperative individuals your survival and reproductive success is helped by also being cooperative. Someone here once posted a really old Dawkins video where he was using the selfish gene and the prisoners dilemma to demonstrate this elegantly.

[ZeeJustin]

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By not desirable do you mean harmful to reproductive success, or just not helpful?

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Harmful to reproductive success. Specifically his own. He could be helpful to the reproductive success of others.

[chezlaw]

It doesn't need to be rare - ant workers are infertile. Rare example are probably rarer as its harder to evolve, but its consistant with darwinism.

chez

[Alex-db]

Im fairly sure this is described to some extent in The Blind Watchmaker.

[Piers]

There stuff like Sickie-cell disease where inheriting the allele from both parents results in sickie-cell disease, but inheriting from just one parent gives increased protection from malaria.

[Bill Haywood]

Genes can reproduce in a way other than procreation -- by helping a related individual to procreate.

In a tiny group on the plains of Africa, the individuals will be closely related. A trait that might kill one individual, but help the group to survive, can be selected for.

Dawkins' _The Selfish Gene_ addresses this.

[Rduke55]

Kin Selection

Along Bill's line, there are plenty of examples of inbred colonies of animals that have self-sacrificing individuals (often in defense of the nest for example). You have to be careful not to extrapolate it to a larger level (species, etc.) because they must be closely related for this to work genetically.

Also, it's pretty complex neutral traits can get passed on regularly and negative traits can get passed on because they have a positive effect in other gene combinations, individuals, or situations (brought up in the gay threads). Also, including eusociality, sometimes it seems like a trait is really negative but actually has a positive effect (sexual cannibalism in mantids and some spiders for example)

[soon2bepro]

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Are there "cases" of genetic traits that are not desirable for reproduction that pass on anyway, and with "reason" (or perhaps I should say non-randomness)?

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Yes.

[soon2bepro]

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It doesn't need to be rare - ant workers are infertile.

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Exactly.