Adaptive production of fighter males: queens of the ant Cardiocondyla adjust the sex ratio under local mate competition Journal Article


Author(s): Cremer, Sylvia; Heinze, Jürgen
Article Title: Adaptive production of fighter males: queens of the ant Cardiocondyla adjust the sex ratio under local mate competition
Affiliation
Abstract: Hamilton's concept of local mate competition (LMC) is the standard model to explain female-biased sex ratios in solitary Hymenoptera. In social Hymenoptera, however, LMC has remained controversial, mainly because manipulation of sex allocation by workers in response to relatedness asymmetries is an additional powerful mechanism of female bias. Furthermore, the predominant mating systems in the social insects are thought to make LMC unlikely. Nevertheless, several species exist in which dispersal of males is limited and mating occurs in the nest. Some of these species, such as the ant Cardiocondyla obscurior, have evolved dimorphic males, with one morph being specialized for dispersal and the other for fighting with nest-mate males over access to females. Such life history, combining sociality and alternative reproductive tactics in males, provides a unique opportunity to test the power of LMC as a selective force leading to female-biased sex ratios in social Hymenoptera. We show that, in concordance with LMC predictions, an experimental increase in queen number leads to a shift in sex allocation in favour of non-dispersing males, but does not influence the proportion of disperser males. Furthermore, we can assign this change in sex allocation at the colony level to the queens and rule out worker manipulation.
Journal Title: Proceedings of the Royal Society of London Series B Biological Sciences
Volume: 269
Issue 1489
ISSN: 0962-8452
Publisher: Royal Society, The  
Date Published: 2002-02-22
Start Page: 417
End Page: 422
URL:
DOI: 10.1098/rspb.2001.1892
Open access: yes (repository)