Triangle plots illustrate the relationships between opsins within the single and double cones of Lake Malawi and Victoria cichlids. Malawian single and double cones vary along two axes, whereas Victorian single and double cones only vary along one. Bar graphs below each plot show expression of the corresponding opsins and emphasize the qualitative differences in expression profiles between lakes. No Lake Victoria taxa express more than trace amounts of SWS1 or Rh2B (open bar), and all express high levels of LWS (filled bar). Opsin expression was measured using real-time PCR. Each point or column represents a different taxon (see Table S1). Triangle plots were generated using a freely available Excel worksheet [74].