Supplemental datasets: Opsin gene expression plasticity and spectral sensitivity in male damselflies could mediate female colour morph detection

The visual systems of Odonata are characterized by many opsin
genes, which form the primary light-sensitive photopigments of the eye.
Female-limited colour polymorphisms are also common in Odonata, with one
morph typically exhibiting male-like (androchrome) colouration and one or
two morphs exhibiting female-specific colouration (gynochromes). These
colour polymorphisms are thought to be maintained by frequency-dependent
sexual conflict, in which males form search images for certain morphs,
causing disproportionate mating harassment.  Here, we investigate
opsin sensitivity and gene expression plasticity in mate-searching males
of the damselfly Ischnura elegans during adult maturation and across
populations with different female morph frequencies. We find evidence for
opsin-specific plasticity in relative and proportional opsin mRNA
expression, suggesting changes in opsin regulation and visual sensitivity
during sexual maturation. In particular, expression of the long-wavelength
sensitive opsin LWF2 changed over development and varied between
populations with different female morph frequencies. UV-Vis analyses
indicate that short- and long-wavelength opsins absorb wavelength of light
between 350 and 650 nm. Assuming opponency between photoreceptors with
distinct short- and long-wavelength sensitivities, these sensitivities
suggest male spectral visual discrimination ability of andromorph and
gynomorph females. Overall, our results suggest that opsin sensitivity and
expression changes contribute to visual tuning that could impact
conspecific discrimination.