Talk:Green-beard effect

Relevance

I don't understand how any of the examples cited actually demonstrate the Green-beard effect. They may indeed be valid examples, but their relevance is not clear. If someone could elaborate on their relevance, I think that would improve this article.

Sukitrebek (talk) 03:18, 1 October 2009 (UTC)

Green beard or monster male?

The first example offered in the section Green-beard effect#Examples is the killing off of certain homozygotes in the red imported fire ant. However, heterozygotes killing off homozygotes is not what is predicted for g.-b. e. genes.

On the other hand, as far as I have understood, killing off homozygotes is a common and perfectly normal behaviour in social hymenopterans: The elimination of "monster males". Recall that these insects are bisexual, with the females (both the reproductors and the workers) being diploid, while the males (only reproductors) are haploid (cf. Haplodiploid sex-determination system). The physical (phenotypic) maleness is directly caused by the haploid individuals being homozygotic in a certain locus (by necessity, since they have only one chromosome of the relevant type, and thus actually are hemizygous), while the females have different variants at that locus, in their two chromosomes of this type.

This biological mechanism has one inherent 'defect': A diploid individual may be homozygotic at the sex-determining locus, since its two chromosoms have identical gene variants. Such individuals will have some male characteristics, but will still be distinguishable from the 'true' (haploid) males. They are sometimes named "monster males"; and they are killed, by the workers or reproducing females (the queens). (This actually may induce some problems for modern honey-bee keepers; due to intentional pure-breeding of bees with good honey production rates, the variability at the sex-determination locus may have fallen drastically, making a tangibly large proportion of the diploid young bees to "monster males", which are killed by their elders.)

Hence, I'd like to know, whether the killed homozygotic BB ants actually were entirely (phenotypically) female, or instead were killed as part of the 'purging out monster male' behaviour. Likewise, I'd like to know, whether a third or more gene variants have been found at this locus; and what happens to other homozygotes.

In particular, are (homozygotic) bb individuals killed or spared? JoergenB (talk) 18:29, 17 May 2012 (UTC)

A response: I think the Green Beard effect here is that the homozygous queens are ok in their own, homozygous, colonies, but when introduced to a polygyne colony are selectively killed by heterozygous workers, rather than homozygous workers (which is why they stay alive in their own colony). So it's not necessarily a trait that all workers respond to, (a monster male, for example), but actually a phenotype-dependent killing response. -Chris — Preceding unsigned comment added by 155.101.104.146 (talk) 18:59, 26 May 2015 (UTC)

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