Plasticity of threespine stickleback nuptial signals: laboratory manipulation of ambient light causes a shift in male reflectance patterns

I caught courting male threespine stickleback (Gasterosteus aculeatus) in Hotel Lake, BC, Canada, and transferred them to one of three experimental lighting environments. Male signal reflectance was measured upon capture from the lake, at one-day post transfer to the experimental light, and at onset of courtship behaviour under artificial light. Male signals responded rapidly to the change in lighting environment following transfer from the wild to the artificial lighting environments and in different ways dependent upon the artificial light composition. Males under red-shifted light had higher signal reflectance in the short wavelength range of the spectrum and less reflectance in the medium and long wavelength range of the spectrum relative to the males in blue-green shifted and full-spectrum lighting. Given the relative prominence of the male stickleback nuptial signal in the behavioural ecology literature, the increasing evidence for the signal's ambient light dependent expression, and the large body of literature based on experiments conducted under artificial light, it would be prudent to repeat some of the classic mate choice experiments under more realistic lighting conditions. ### Competing Interest Statement The authors have declared no competing interest.