Behavioural trait assortment in a social network: patterns and implications

D P Croft, J Krause, S K Darden, I W Ramnarine, J J Faria, Richard James

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205 Citations (SciVal)


The social fine structure of a population plays a central role in ecological and evolutionary processes. Whilst many studies have investigated how morphological traits such as size affect social structure of populations, comparatively little is known about the influence of behaviours such as boldness and shyness. Using information on social interactions in a wild population of Trinidadian guppies (Poecilia reticulata), we construct a social network. For each individual in the network, we quantify its behavioural phenotype using two measures of boldness, predator inspection tendency, a repeatable and reliably measured behaviour well studied in the context of co-operation, and shoaling tendency. We observe striking heterogeneity in contact patterns, with strong ties being positively assorted and weak ties negatively assorted by our measured behavioural traits. Moreover, shy fish had more network connections than bold fish and these were on average stronger. In other words, social fine structure is strongly influenced by behavioural trait. We assert that such structure will have implications for the outcome of selection on behavioural traits and we speculate that the observed positive assortment may act as an amplifier of selection contributing to the maintenance of co-operation during predator inspection.
Original languageEnglish
Pages (from-to)1495-1503
Number of pages9
JournalBehavioral Ecology and Sociobiology
Issue number10
Early online date15 Jun 2009
Publication statusPublished - 1 Aug 2009


  • Poecilia reticulata
  • Guppy
  • Co-operation
  • Personality
  • sticklebacks
  • evolution
  • tit-for-tat
  • risk
  • Predator inspection
  • fish shoals
  • cooperation
  • predator inspection
  • assortative interactions
  • Evolutionary graph theory
  • Behavioural phenotype
  • individual-differences
  • guppy poecilia-reticulata


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