Genetic analysis of fluctuating asymmetry for skeletal characters in mice

Fluctuating asymmetry (FA)--nondirectional variation between left and right sides of bilateral characters--has become increasingly used as a measure of developmental stability. In the comparison of stability levels among various populations, however, it often has been assumed that FA does not have a genetic basis (i.e., its heritability is zero). To test this hypothesis, heritabilities were estimated via maximum likelihood correlations of parents and offspring for FA in eight quasi-continuous skeletal characters (primarily presence/absence of various foramina) in randombred house mice. Genetic correlations between left and right sides for each of the characters also were calculated to test whether they were one, as would be predicted if differences between sides are purely environmental in origin. Heritabilities of FA in all eight characters were not significantly different from zero, as hypothesized, their mean value being very low (0.032). Similarly, genetic correlations between sides were not significantly different from one for most of the characters. It was concluded that for this specific population of mice, there was no detectable additive genetic variance for FA.