Opsin expression predicts male nuptial color in threespine stickleback

Abstract

Theoretical models of sexual selection suggest that male courtship signals can evolve through the build‐up of genetic correlations between the male signal and female preference. When preference is mediated via increased sensitivity of the signal characteristics, correlations between male signal and perception/sensitivity are expected. When signal expression is limited to males, we would expect to find signal‐sensitivity correlations in males. Here, we document such a correlation within a breeding population of threespine stickleback mediated by differences in opsin expression. Males with redder nuptial coloration express more long‐wavelength‐sensitive (LWS) opsin, making them more sensitive to orange and red. This correlation is not an artifact of shared tuning to the optical microhabitat. Such correlations are an essential feature of many models of sexual selection, and our results highlight the potential importance of opsin expression variation as a substrate for signal‐preference evolution. Finally, these results suggest a potential sensory mechanism that could drive negative frequency‐dependent selection via male–male competition and thus maintain variation in male nuptial color.

Microhabitat contributes to microgeographic divergence in threespine stickleback

“…2017; Brock et al. 2018; Veen et al. 2017) have mostly ignored effects of distance, assuming there is no IBD for nests within an area spanning tens of meters.…”

“…2017; Brock et al. 2018), opsin gene expression (Veen et al. 2017), and immune cell repertoire and activity (Bolnick et al.…”

“…2017; Brock et al. 2018). Typically, nest depth varies perpendicular to the shoreline (e.g., between nests a few horizontal meters apart), rather than along shore.…”

Parallel shifts of visual sensitivity and body colouration in replicate populations of extremophile fish

“…African cichlids (Seehausen et al 2008) and threespine stickleback (Boughman 2001) are among the few systems where sensory drive seems to explain patterns of co-evolution between shifts in female visual perception and male nuptial colouration. In general, few studies have described a pattern of coevolution between visual perception and body pigmentation (but see (Brock et al 2018)) or determined the pattern of evolution of each trait in relation to ambient light. Thus, it remains unclear what ecological mechanisms most often drive shifts in body pigmentation and visual sensitivity.…”

Parallel shifts of visual sensitivity and body coloration in replicate populations of extremophile fish

“…African cichlids (Seehausen et al, 2008) and threespine stickleback (Boughman, 2001) are among the few systems in which sensory drive seems to explain patterns of co‐evolution between shifts in female visual perception and male nuptial coloration. Previous work has attempted to understand this connection by linking the evolutionary rate of opsin genes (Bloch et al, 2015; Bloch Price et al, 2015) or opsin gene expression (Brock et al, 2018; Sandkam, Young, Breden, Bourne, et al, 2015) with male nuptial coloration, or with ambient light (Fuller et al, 2004, 2005). To tease apart the most common ecological mechanisms that drive shifts in body pigmentation and visual sensitivity, further studies are needed.…”