Biochemical heterozygosity and morphological variability: interpopulational versus intrapopulational analyses.

The literature is replete with articles suggesting the existence of a relationship between variability at biochemical loci and morphological variation in various animal populations, including humans. With few exceptions these previous studies have utilized an interpopulational approach by examining levels of heterozygosity between modal and extreme phenotypes, typically by use of analysis of variance. Here we consider these purported relationships in a midwestern Mennonite population (n = 890) by correlating individual biochemical heterozygosity and deviation from the mean for anthropometric traits. The results of this intrapopulational correlation indicate that (1) with protection for multiple tests, there are few significant correlations and these have low R2 values, and (2) males and females show different patterns of correlation (males negative, females positive). Based on these findings, the results of earlier studies are in question because nonprotected alpha values are used for multiple tests and heterozygosity is calculated on the basis of a few highly heterozygous blood group systems and is assumed to be representative of the heterozygosity for the entire genome. In general, no evidence is found to support the concept of a direct relationship between biochemical heterozygosity and morphological variability.