Queen acceptance in a socially polymorphic ant

Abstract

A central question in social evolution is what processes regulate the number of breeders in each social group. Here, we tested whether differences in the rate of acceptance of new queens by resident workers could be a proximate cause explaining the coexistence of single-and multiple-queen colonies in an ant population. We found that Formica selysi workers discriminated against foreign (non-nestmate) queens, which contributes to maintaining the genetic integrity of the social group essential to kin selection. All the young and newly mated foreign queens introduced into experimental groups of workers died within 48 h. In contrast, workers frequently accepted young newly mated nestmate queens. The survival of nestmate queens was not significantly lower in groups of workers originating from single-queen colonies than in groups of workers originating from multiple-queen colonies. Finally, virgin queens had significantly higher survival than mated queens. Together, these results show that the maintenance of singlequeen and multiple-queen colonies in the same population is unlikely to be caused by strong differences between the two types of colonies in their rate of acceptance of new queens by workers. They also suggest that the discrimination of queens by resident workers restricts the dispersal of foreign queens among colonies, but not the acceptance of additional nestmate queens.

Bidirectional Shifts in Colony Queen Number in a Socially Polymorphic Ant Population

“…A degree of lability in social structure is consistent with previous experiments that showed that F. selysi queens from both social forms can establish colonies either independently or in associations (Reber et al 2010) and that colonies of both social forms tend to reject unrelated queens, but will often accept nestmate queens (Meunier et al 2011). However, cross‐fostering experiments revealed that size differences between monogynous and polygynous queens, as well as the development time and growth rate of worker brood, matched their social origin, rather than their fostered environment (Meunier and Chapuisat 2009; Purcell and Chapuisat 2012).…”

“…Overall, our results highlight the great diversity of reproductive strategies exhibited by social insects (Heinze and Keller 2000). In particular, joining unrelated colonies or taking over queenless nests appear to be viable options for young queens, in addition to staying in the maternal nest (Meunier et al 2011) or founding a new colony independently (Reber et al 2010).…”

The influence of social structure on brood survival and development in a socially polymorphic ant: insights from a cross‐fostering experiment

“…These overall patterns are probably consistent across socially polymorphic ant species, because social structure variation is generally associated with similar life history changes and morphological variation in queens and workers (Bourke & Franks, ; Heinze & Keller, ; Schwander et al ., and references herein). However, we do not yet have direct evidence that the social forms of F. selysi differ in their dispersal and colony founding strategies (Reber et al ., ; Meunier et al ., ).…”

Can alternative pathways mediate the influence of queen number on nestmate discrimination in ants?

“…In particular, both types of workers were more aggressive towards introduced foreign workers from the alternative rather than identical social form, 11 and monogyne workers were significantly more aggressive towards foreign queens of monogyne than polygyne origin. 12 The influence of queen number on the chemical signatures of workers has also been reported in two other ant species. In Messor barbatus, 13 where the social origin of introduced workers influences their acceptance in monogyne colonies, 14 and in the fire ant Solenopsis invicta, 15 where nestmate discrimination depends on the alleles of the gene Gp-9 present in the individuals and in the recipient colony.…”