Abstract
Optomotor studies have shown that three-spined sticklebacks (Gasterosteus aculeatus) are more sensitive to red during summer than winter, which may be related to the need to detect the red breeding colour of males. This study aimed to determine whether this change of red light sensitivity is specifically related to reproductive physiology. The mRNA levels of opsin genes were examined in the retinae of sexually mature and immature fish, as well as in sham-operated males, castrated control males, or castrated males implanted with androgen 11-ketoandrostenedione (11 KA), maintained under stimulatory (L16:D8) or inhibitory (L8:D16) photoperiods. In both sexes, red-sensitive opsin gene (lws) mRNA levels were higher in sexually mature than in immature fish. Under L16:D8, lws mRNA levels were higher in intact than in castrated males, and were up-regulated by 11 KA treatment in castrated males. Moreover, electroretinogram data confirmed that sexual maturation resulted in higher relative red spectral sensitivity. Mature males under L16:D8 were more sensitive to red light than males under L8:D16. Red light sensitivity under L16:D8 was diminished by castration, but increased by 11 KA treatment. Thus, in sexually mature male sticklebacks, androgen is a key factor in enhancing sensitivity to red light via regulation of opsin gene expression. This is the first study to demonstrate that sex hormones can regulate spectral vision sensitivity.
Highlights
Sexual selection requires the ability to find/attract a partner, and to discern a partner of high quality [1]
General Castrated males were observed to have lower body weights than sham-operated males, but otherwise no significant differences in body weight were observed between experimental groups of the same sex (Table 1)
Under both long and short day conditions, 12 of 15 of the castrated males treated with 11 KA exhibited breeding colours; the Kidney-Somatic Index (KSI) of castrated fish treated with 11 KA were higher than those of castrated control fish, and KSIs were slightly higher in the former maintained under long photoperiods than equivalents under short photoperiods (p = 0.05)
Summary
Sexual selection requires the ability to find/attract a partner, and to discern a partner of high quality [1]. Partners are located and attracted via various sensory systems. One or both potential partners emit signals, which can include pheromones, mating calls, or breeding colours. One or both partners recognize and react to the signals using the appropriate sensory system, such as olfaction, hearing, or vision [2]. All other things being equal, the more successful an organism is at sending and/or receiving signals, the more successful it will be at attracting/choosing partners of high quality and/or in high quantity, and at disseminating its genes [2]. Mating signals can be as important for rivals as they are for potential mates [4,5]. It is important for territorial males to be able to detect the presence of competitors [6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
