Heritability examples

Examples of studies of the heritability of behavioral phenotypes

Why might additive genetic variation persist over evolutionary time? There are four mechanisms which commonly explain this:

balancing selection, in which more than one phenotype is favored. This could occur among animals in the same generation (as in calling males and satellite males in a mating chorus) or between generations, as environmental conditions shift.
epistasis, or interactions among genes. While one phenotype may be favored, the alleles's effects on other genes may be deleterious, preventing fixation of the allele in evolutionary time.
correlated characteristics in males and females. If a trait which is important in one sex, either for competition for mates (as in horns or antlers in male ungulates) or in mate choice, is produced by both sexes, then the deleterious effect on the other sex may outweigh selection for maximizing the trait. For example, Cuervo et al. (1996) found that in barn swallows tail length varies in both males and females but is a sexually selected trait only in males.
the handicap principle. If producing a phenotype is costly enough, selection against extreme individuals may counterbalance selection favoring that phenotype. This is a form of balancing selection, driven by the cost of the phenotype.

Example 1: Mating in a moth

Male lesser wax moths, Achroia grisella, attract their mates with ultrasonic calls. Male calls vary, and the variation is heritable. However, females also show heritable variation in their choice of calls. This variation in female preference is a good explanation for the persistence of heritability in the males; when the females prefer alternative phenotypes, the additive genetic variation persists.

Example 2: Dominance behavior in Japanese quail

Example 3: Mating in a Drosophila.

There are many species of fruit fly other than the common laboratory version. These display many interesting variations in mating behavior. In the picture winged fly, Drosophila sylvestris, male aggression, size, and shape all have low (not significantly different from zero) heritabilities, as did overall mating success. This result suggests that traits used in mate choice have been subjected to intense selection, which has exhausted the additive genetic variance.

Example 4: Neural centers for song production in zebra finches

Boake C. R. B., Konigsberg L. 1998. Inheritance of male courtship behavior, aggressive success, and body size in Drosophila silvestris Evolution 52: (5) 1487-1492.
Cuervo J. , de Lope F., and Moller A. 1996. The function of long tails in female barn swallows (Hirundo rustica): an experimental study. Behavioral Ecology, Vol 7:132-136.
Jang, Y. W. et al. 1998. Absolute versus relative measurements of sexual selection: assessing the contribution of ultrasonic signal characters to mate attraction in the Lesser Wax Moth. Achroia grisella (Lepidoptera Pyralidae). Evolution 52:1383-1394.
Jang YW, Greenfield MD 2000 Quantitative genetics of female choice in an ultrasonic pyralid moth, Achroia grisella: variation and evolvability of preference along multiple dimensions of the male advertisement signal HEREDITY 84: (1) 73-80
Nol E., Cheng K., Nichols C. 1996. Heritability and phenotypic correlations of behaviour and dominance rank of Japanese quail. Animal Behaviour 52: 813-820