The conventional gender roles associated with male and female shorebirds are reversed when there are more adult males in a species. The finding is reported in a paper published in Nature Communications this week.
In nature, there seems to be a set of conventional roles associated with males and a separate set of roles for females. Males often compete for access to females while females are usually devoted to parental care. Some species have, however, been shown to reverse these roles.
Andras Liker and collaborators prove for the first time that social environment has a strong influence on the breeding system in shorebirds. Their data suggest that shorebird species with more adult females than males will show conventional sex roles, but species with more adult males than females will present reversed sex roles, with females competing for mates and males carrying out parental care. Male and female behaviour can thus change in evolutionary terms in response to adult sex ratio.
Adult sex ratio not only appears to be associated with mating and parental behaviour but it might influence other aspects of social behaviour. The authors discuss the possibility of homosexual pairing or cooperative breeding to be also influenced by adult sex ratio, although additional research will be required to provide a further line of evidence on that front.