Data from: Dialogues in colour and behaviour: Integration of complex signalling traits and physiology

Animal communication can be complex and costly, involving multiple traits
that vary in redundancy. To understand how dynamic signals are integrated,
we staged male-male interactions between size-matched individuals of
Psammophilus dorsalis, and measured display behaviours, the maximum
chromatic contrast of dynamically changing skin colours, and size of
ultraviolet patches. We also measured testosterone and corticosterone
levels induced by the social interaction. All signalling traits condensed
in a principal component analysis into two main components – PC1,
comprising of behaviours (number of headbobs and shudders) and ultraviolet
(UV) patch size, and PC2, representing the dorsal and lateral body
colours. Testosterone levels were positively associated with PC1, and both
testosterone and corticosterone levels were negatively associated with
PC2. Our results suggest that the chromatic contrasts of colours are
non-redundant with the intensity of behaviours, and that size of UV
patches better reflect behavioural intensity than other colour components.
We also found that individuals matched the intensity of display behaviours
and the contrast of their dorsal (but not lateral) colours with their
opponents. Overall, these results highlight how multiple dynamic signals,
which change in response to opponents during social interactions, can be
maintained by both internal mechanisms (i.e. hormones) as well as through
non-redundancy.