Effects of UV Light Exposure on Relative UV Opsin Genes rh3 Expression and Sexual Behaviour in Cosmophasis umbratica
by Rachel Seah Wan Xin | Author
Abstract ID: 186
Event: The 3rd AsiaEvo Conference
Topic: The evolution of invertebrate sensory ecology and behaviours
Presenter Name: Rachel Seah Wan Xin

Surrounded by a world of light and colours, the visual systems of animals help them to detect and discern different wavelengths of light. While the visible wavelength of light falls within the 400-700nm range, the ultraviolet range of light (280nm - 400nm) is a field of vision that only some animals are privy to. Visual pigments found in retinas called opsins are responsible for light sensitivity in organisms. Among invertebrates, the opsin gene rh3 is responsible for the detection of UV light. Studies have revealed that the visual systems is highly plastic; exposure to different lighting conditions can induce significant changes in opsins gene expressions among vertebrates. Due to a dearth of studies on the plasticity of the visual systems in invertebrates, our study makes use of Cosmophasis umbratica, a tropical ornate spider that is well known for using UV light for communication and sexual behaviour. We aim to determine the effects of UV light exposure on both the behavioural and molecular levels in the different life stages of C. umbratica. On the molecular front, the results of our study indicate that the interaction between the life stage of C. umbratica and the lighting conditions that they are exposed to, influences the relative expression of rh3. Between the dark and light (UV-) treatment, our study found no significance difference in rh3 gene expression for all life stages (juveniles, adult females, adult males). However, UV light treatment (UV+) induced a decrease in rh3 expression in juveniles, an increase in rh3 expression for females but there was no significant difference in rh3 expression in males. These preliminary findings suggest the high plasticity of the UV visual systems in relation to the life stages and environmental lighting conditions of C. umbratica. In conclusion, this study offers insights into the role of UV in influencing visually guided sexual behaviour and opsin gene expression. It is our hopes that this study sets the wheels in motion for further investigations into the genetic basis of sexual behaviour mechanisms that underlie the plasticity of visual systems in invertebrates.