Evolutionary genetics of fluctuating asymmetry in the peacock butterfly( Inachis io )

Fluctuating asymmetry (FA) and trait size were analysed for two pupal and two adult traits in the peacock butterfly ( Inachis io L.). Natural families were raised in the field and the laboratory. The amount of FA relative to trait size was lower for the measured pupal traits. Although there were clear differences in trait sizes between the sexes and between the laboratory and field, no differences in FA were detected. Individuals that died in the pupal stage or hatched with crippled wings did not differ in their amount of FA from healthy adults. Differences for the trait sizes between families were large and significant and the heritabilities ( h 2 ) were high. For FA most differences between families were not significant and h 2 s were close to and not different from 0. Only for one of the pupal traits was a significant difference detected between families but its h 2 (0.15) was not significantly different from 0. Differences in survival between families were not related to their average FA. Although half of the phenotypic correlations between trait sizes were significantly different from 0, only one correlation between FA (for the adult traits) was significant, albeit weakly ( r =0.11). Some of the genetic correlations between trait sizes were strong and significant, but genetic correlations between FA were practically absent because of the low amounts of genetic variation for FA. A purely random cause of FA seems more likely for these traits than any influence of sex, environment, quality or genes.