Figure 4. Pattern variations in actual hybrid animals.

Artificial hybrids between female (rows) and male (columns) salmonid species and the binarized images of their body patterns (taken from Fig. 2 and study by Suzuki and Fukuda23). Interspecific hybrids within the 'white spots' group (a) have white spots. Intergeneric hybrids between the 'white spots' group and the 'black spots' group mostly display labyrinthine patterns (b, c). Interspecific and intergeneric hybrids within the 'black spots' group (d) have black spots. Scale bar, 10 cm. (e) Quantification of colour patterns. The complexity of each colour pattern (lower score means higher complexity; see Methods section) is plotted against the overall colour tone of the pattern (defined as the ratio of white area). Hybrids between 'white spots' species and 'black spots' species (red circles) have more complex patterns than those of the parent species (white or black squares), whereas they have intermediate values for the overall colour tone. Hybrids within the 'white spots' group (white circles) and within the 'black spots' group (black circles) have similar values for both indices to the parents. Blue dots denote calculated patterns using the RD model.