The role of boundary length and adjacent patch contrast in guppy mate choice: Dataset, Matlab and R codes

The presence of various combinations of adjacent colours within polymorphic species' colour pattern could have a major impact on mate choice. We studied the role of pattern geometry in predicting mate choice in guppies using boundary strength analysis (BSA). BSA estimates the visual contrast intensity between two adjacent colour patches (ΔS) weighted by the lengths of the boundaries between these adjacent colour patches. We measured both the chromatic (hue and saturation) and achromatic (luminance) ΔS for each pair of adjacent patches. For each male's colour pattern, we measured BSA as both mean (mΔS) and coefficient of variation (cvΔS) of all ΔS weighted by their corresponding boundary lengths. We also determined if specific colour patch boundaries had an impact on female preferences and whether these predicted overall male contrast (mΔS). We found that males with a higher mΔS were more attractive to females and that six boundaries containing either fuzzy black or black as one of the pair colours significantly affected female preferences, indicating that (1) females favoured highly conspicuous males and (2) melanin-based patches could be used as a signal amplifier, not only for orange but for other colours.