Selection for tameness alters play-like behaviour in red junglefowl in line with effects of domestication.

Abstract

The phenotypic alterations brought by domestication have been hypothesized to be driven by selection for tameness. To explore this, we selected red junglefowl (RJF) for high (HF) and low (LF) fear of humans for 14 generations. We previously found that domesticated chickens performed more play-like behaviours during early ontogeny, and therefore, in this study, we explored potential effects of tameness. Groups of three to four chicks were randomly created from each selection line, and each group was moved to an enriched play arena twice per week, from day 6 until day 53 post-hatch. The frequency of 14 different play-like behaviours, categorized as locomotor, social and object play-like behaviour were recorded for 30 min at every observation instance. Every group of three or four birds constituted the independent statistical replicates and measures were averaged within the groups. The frequency of total play-like behaviour as well as object, and locomotor play-like behaviour was significantly higher in LF, while social play-like behaviour was significantly more common in HF. This largely mirrors previous observations of differences between domesticated and ancestral chickens. Hence, our results support the important role of tameness for the evolution of domesticated behaviour.