Behavioural experiments showed that male aggression related to territory
selection and its defence is reduced in SP males. Further, SP females were never chosen. At the brain level we
demonstrated that GnRH3 neuronal optical density of staining was reduced. Finally, at the pituitary level we
showed that SP males showed low levels of β-LH, PRL and GH in the pituitary, and that SP females showed no
significant differences in the pituitary content of any hormone. Taken all together these results suggest that
in C. dimerus the photoperiod is a relevant environmental cue related to reproductive behaviour and
physiology.