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

Abstract

The evolution of social life is usually associated with capabilities of individuals to protect group boundaries against foreign individuals. In colonies of ants, the number of reproductive queens is known to influence the accuracy of nestmate discrimination by resident workers. However, the pathway by which this effect is mediated remains unclear. The major hypothesis has long been that workers from multiple-queen colonies commit more discrimination errors against foreigners because their colonies contain a broader diversity of genetically determined cues characterising colony membership. Until recently, this hypothesis has received little attention and poor empirical support. In a recent study, Meunier et al.¹ proposed an alternative, albeit not mutually exclusive hypothesis. The presence of one or multiple queens modifies chemical signals on colony members that trigger aggressive or cooperative behaviours during foreign encounters. Here, I detail how this new hypothesis is congruent with previous results and discuss potential limits and evolutionary implications of the two suggested hypotheses.

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Figures and Tables

Figure 1 The social origin of workers, queens and queen-laid eggs significantly influences the level of aggression they receive from foreign conspecific workers from (white) monogyne and (black) polygyne colonies in the ant Formica selysi. Workers' aggressiveness is (+) high, (++) very high or (−) non-significant. Results are detailed in references 1, 11, 12 and 20.

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