Science Forums 2

[mynah]

I've thought of a way in which a shortage of females may occur... Just my own speculation and possibly a bit far out, but here it is:

In birds, females are the heterogametic sex, i.e. the one with two different sex chromosomes (as opposed to mammals, where it is the male). Having just one copy of the sex chromosome leaves the carrier vulnerable to a wider range of genetic problems than would otherwise have been the case. Could polyandrous species have suffered from an unusually severe load of sex-linked problems, leading to a markedly skewed male:female ratio? It would be interesting to know whether or not the ratio is skewed in polyandrous species. (It is in polygynous species, where conspicuous males encumbered with extravagant display feathers often fall prey to predators.)