The genetics of colour-patterns in the grasshopper Chorthippus brunneus

Abstract

Several alleles were found to determine the colour of the dorsal pronotum in Chorthippus brunneus; there was evidence for at least two loci (C and V). Brown (CB)was the universal recessive and green (CC) was dominant to all other colours. The white allele (CW)was codominant with green(CG)and purple (CP). Wing-patterns were determined by a separate, probably linked locus (W). A dominant plain wing-pattern (WP) was associated with colours other than brown. Striped(WS)and mottled(Wmo) were codominant and a plain recessive allele (WP) was also found. All three alleles were associated with the brown phenotype. A purple-sided allele (SPu) was sometimes obmd with Cpu.. SPu was dominant to brown sides (SB), A series of markings on the dorsal and lateral pronotum (linea intermedia, fascia postocularis, linea media, carina media and zona lateralis) were investigated and found to be controlled at separate loci which may be linked to W. These characters were expressed by dominant alleles. Epistatic effects by modifier loci were shown to have an important effect on the determination of wing phenotype. Allele Wo+, for example, suppressed the stripe-wing pattern, linea media, carina media and zona lateralis. It was concluded that colour patterns appear to be under genetic control and that dominant alleles were rare in the wild. Changes in shades of colours were shown to be age-dependent and minor.