Insectes Sociaux

, Volume 53, Issue 2, pp 127–135 | Cite as

Kin recognition and the paradoxical patterns of aggression between colonies of a Mojave desert Pheidole ant

Research article


Populations of the desert seed-harvesting ant Pheidole xerophylla are often characterized by high nest density leading to competitive interactions between foragers from different nests. We investigated the inter-nest aggression, spatial distribution and genetic structure of a P. xerophylla population of the Mojave Desert in Southern California. Inter-nest aggression was quantified by standardized staged encounters in a neutral arena. Genetic relatedness within nests and relatedness between nests were calculated using allelic frequencies at four microsatellite-DNA loci. We found a bimodal distribution of inter-colony aggression levels with a first mode at low aggression levels and another mode at much higher aggression levels. Inter-colony aggression levels were largely non-transitive. No effect of geographical distance on inter-nest aggression levels was detected. Despite high amounts of variation in inter-colony relatedness ( − 0.24 to 0.37) this variable did not correlate with the level of aggression between nests. Intra-nest relatedness ranged from 0.40 to 0.75 and close inspection of worker genotypes within colonies revealed a high proportion of polygynous colonies or a mixture of polygyny and polyandry. Aggression levels among nests was found to decrease with increasing intra-nest relatedness. These results do not support the idea that aggression is modulated by a nestmate recognition mechanism based on overall genetic similarity. Instead, the absence of transitivity found in inter-colony aggression and bimodal distribution of aggression levels are compatible with a common label acceptance model of nestmate recognition and suggest that label diversity may be encoded by a limited number of loci.


Nestmate recognition intraspecific competition endogenous cues exogenous cues common label acceptance model 


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Copyright information

© Birkhäuser Verlag, Basel 2006

Authors and Affiliations

  1. 1.Department of EntomologyUniversity of California DavisDavisUSA
  2. 2.Behavioral and Evolutionary Ecology CPFree University of BrusselsBelgium
  3. 3.Department of Ecology and Evolutionary BiologyUniversity of California Los AngelesLos AngelesUSA
  4. 4.Department of Ecology and Evolution, Bâtiment de BiologieUniversity of LausanneLausanneSwitzerland

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