Fig. 1.
Phenotypic evolution of M/LWS pigments in Rodentia and Afrotheria. (A) Values of λmax for M/LWS for extant and ancestral taxa. The values obtained in this study by either direct measurement (*) or estimation from critical sites (†). Published λmax values are based on either direct measurements or sequence-based predictions (Dataset S1). Across the two clades, branches and λmax values are colored by wavelength sensitivity, as yellow (550 nm to 556 nm), green (≤549 nm), and blue (490 nm). Gray indicates no value. Predicted values are shown in italics. For branches leading to gerbil and elephant-shrew, all amino acid substitutions are shown, with critical sites identified here underlined. Other focal branches show known critical substitutions only (bold) (7). For gerbil and elephant-shrew, recorded absorbance peaks (difference spectra) and λmax values for all three pigments are shown. (B) Phylogenetic tree showing position of the focal orders Rodentia and Macroscelidea (7). Published λmax values for each mammalian order are shown as either ranges (black bars) or single point values (black triangles). The λmax values measured in this study are indicated by red triangles (Dataset S1).