The genetics of spot pattern characters in the meadow brown butterfly Maniola jurtina (Lepidoptera: Satyrinae)

Abstract

The control of spot pattern variation on both hindwing and forewing in 16 F1 broods of Maniola jurtina is analysed. Substantial additive genetic variance was demonstrated for each of the spot pattern characters. For example, estimates for heritability of hindwing spot-number were 0·66±0·11 in males and 0·89±0·11 in females. These estimates were essentially the same when four broods with extremes of low or high mortality were excluded from the analysis. The hindwing traits showed a consistent pattern of a closer resemblance of offspring to the same sex than to the opposite sex parent. This can also be expressed in a genetic correlation between the same trait in the two sexes that is (much) less than 1·0. Further analysis strongly suggested that this follows from a partially sex-dependent expression of some of the individual spots. In constrast to the hindwing traits, there may be a maternal effect in the inheritance of the forewing “eyespot”. The fact that relative differences in spot-number between populations tended to be maintained when wild larvae were reared in the laboratory and experiments which showed no significant influence of varying temperature or relative humidity during periods of the pupal stage on spot phenotype suggest that the estimates of heritability are likely to be close to those which pertain in natural conditions. Analysis of data for relative hindwing spot-size in the broods provides some support for a threshold model for spot development.