Rhesus macaque cone ratio heritability

A defining feature of catarrhine primates is uniform trichromacy – the ability to distinguish red (long; L), green (medium; M), and blue (short; S) wavelengths of light. While the tuning of photoreceptors is conserved, the ratio of L:M cones in the retina is variable within and between species, with human cone ratios differing from other catarrhines. Yet, the sources and structure of variation in cone ratios are poorly understood, precluding a broader understanding of color vision variability. Here, we report a large-scale study of a pedigreed population of macaques. We collected foveal RNA and analysed opsin gene expression using cDNA. We estimated the additive genetic variance of cone ratios. The average L:M ratio and standard error was 1.03:1± 0.02. There was no age effect, and genetic contribution to variation was negligible. We found marginal sex effects with females having larger ratios than males. S cone ratios (0.143: 1± 0.002) had significant genetic variance with a heritabilit...