Meeting Abstract

P1.95  Monday, Jan. 4  O, DARWIN, OUR OPSIN GENES ARE SO MANY, BUT OUR EXPRESSED OPSINS ARE SO FEW – A GENE EXPRESSION ‘TALE’ OF THE 10-OPSIN GENE REPERTOIRE IN GUPPIES (Poecilia reticulata) CHRISTOPHER, R.J. Laver*; JOHN, S. Taylor; University of Victoria; University of Victoria claver@uvic.ca

Despite the remarkable physiological similarities among vertebrate eyes, it is increasingly clear that visual perception can vary, among and even within closely related species, with many animals evolving or ‘tuning’ their visual-pigments (opsins) to spectral selective pressures in the environment. Such tuning has resulted in a diversity of opsin gene repertoires that can vary greatly in sequence, copy number, and expression among species. Remarkably, the guppy (Poecilia reticulata) contains 10 opsin genes predicted to be most sensitive to different wavelengths of light. This observation, coupled with studies showing that guppy male reproductive fitness is positively correlated with conspicuous red, orange, and yellow colorations, suggests that increased spectral discrimination of male coloration might be a selective force driving opsin gene duplication and divergence in this species. Since guppy embryos as well as juveniles do not show these characteristic colors, and by definition are not sexually active, we hypothesize that variation in long-wavelength sensitive (LWS) opsin expression will coincide with sexual maturity. Using real-time RT-qPCR, we show that juveniles and adults predominantly express (>95% relative abundance) three or four of their nine cone opsin genes, with sex-specific upregulation of LWS A180 in males and LWS S180 in females. Although the functional significance of this expression pattern is unknown, males and females are likely to exhibit differential wavelength sensitivity and/or discrimination. Intriguingly, the only other taxa with sex-specific differences in opsin gene expression are the lycaenid butterflies, where color-based sexual selection has also been demonstrated.