Figure 2.

Exemplary chromatograms of direct PCR‐sequencing for partial exon 3 and exon 5 of M/LWS opsin genes from (a) a female howler monkey with one standard LWS and one standard MWS opsin genes on each X chromosome and (b) a female howler with one X chromosome carrying a standard LWS and a standard MWS opsin genes and the other X chromosome carrying a standard LWS opsin gene and an M‐L hybrid opsin gene. Amino acid site number is indicated in the top row. Amino acid abbreviations are given in the second row. The nucleotide reads are indicated in the third row. Letters and chromatograms for adenine, guanine, cytosine, and thymine are colored with green, black, blue, and red, respectively. The three spectral tuning amino acid site numbers, 180, 277, and 285 are highlighted in blue and enclosed in boxes. The L‐type and M‐type amino acids at the three sites are colored with red and green, respectively. Amino acid heterozygosity is apparent at the three sites by the double peaks. Note that double peaks are approximately the same height except at site 285 of the normal plus hybrid opsin gene (b)