Figure 1

Xiphophorus species/strains used. Adult morphologies of X. helleri (A) and X. maculatus (C) used in this study as representatives of the swordtail and platyfish lineages. Overview and nomenclature of adult fin rays (B) in the sword [21] of X. helleri and in the gonopodium [33] that is formed by swordtails and platyfish males. The caudal fin ray overgrowth mutant brushtail (D). Note that C and D show different strains of X. maculatus that exhibit dissimilar body colouration independent of the brushtail mutation.