Similarity in sex and reproductive state, but not relatedness, influence the strength of association in the social network of feral horses in the Blauwe Kamer reserve

Amos Bouskila, Emmanuel Lourie, Shirli Sommer, Han de Vries, Zef M. Hermans, Machteld van Dierendonck

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

© 2016 Informa UK Limited, trading as Taylor & Francis Group.Relatedness is likely to affect the decisions of animals regarding their affiliations with conspecifics. Social network analysis provides tools to describe the social structure of animals. Here, we investigate the social network of a population of 27 unmanaged Konik horses in the Blauwe Kamer Nature Reserve, in the Netherlands. We test three hypotheses: (1) that related individuals will have stronger associations; (2) that individuals with low values of average relatedness to their neighbors in the network will have more links and (3) homophily, the tendency of individuals to associate with similar others, will lead to stronger associations among individuals of similar sex, reproductive state, age and rank in the social network. We videotaped 22 horses (excluding foals) and their interactions. Relatedness was calculated from the pedigree, which was based on parentage, determined by DNA analysis. The social network was based on spatial proximity data. There was no significant influence of relatedness on strength of associations in the network or an influence of age- or rank-homophily. We argue that the lack of a relatedness effect is not likely to have been caused by an inability to detect kinship. Strength of associations in the social network was significantly affected by the tendency of the horses to associate with individuals of the same sex and the same reproductive state. This social network pattern is not common in mammals, and the study of unexplained variation in choice and strength of associations may have important implications for other equids increasingly confined to reserves worldwide.
Original languageEnglish
Pages (from-to)106-113
Number of pages8
JournalIsrael Journal of Ecology and Evolution
Volume61
Issue number2
DOIs
Publication statusPublished - 2016

Keywords

  • female defense polygyny
  • feral horses
  • kin detection
  • long-term affiliation
  • proximity

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