CASTELLANO,, M.; HARA,, E.; HEWS,, D. K. : Female Sceloporus virgatus lizards exhibit a left eye – right hemisphere preference when performing aggressive rejection displays to conspecific males

In a small but taxonomically diverse number of vertebrates, there is a left-eye preference / right hemisphere specialization for aggression. Laterality for aggression has been demonstrated only in males. Here we present results consistent with the hypothesis of a left-eye / right hemisphere specialization for aggressive courtship rejection display in female striped plateau lizards, Sceloporus virgatus. Many lizards use postural displays to signal aggression, and lateral eye placement prevents binocular vision of such displays. The rejection display of gravid female S. virgatus involves dorsolateral flattening and arching of the back. In a field study we introduced stimulus males into either the left visual field (LVF) or right visual field (RVF) of free-ranging gravid females. When males were introduced in the RVF, females were equally likely to use either the LVF or RVF to perform their first aggressive display. In contrast, when males were introduced into the female’s LVF, females were significantly more likely than expected by chance to continue to use their LVF to view the intruder when performing the first aggressive display. These results suggest that mechanisms mediating lateralization may be similar in males and females. This is one of only a few examples of laterality of brain function demonstrated in a free-ranging vertebrate and the first for females.