Population structure and genetic heterogeneity in the Upper Markham valley of New Guinea

An analysis is presented of the standardized Wahlund's variances (f) in gene frequencies of the ABO, Rh and MNS blood group systems among 19 villages of the Atsera isolate of the upper Markham Valley, Papua New Guinea. In the past, there has been some disagreement over the relative importance of population structure and natural selection in the determination of these variances. The Lewontin‐Krakauer test is presented as a means of resolving this disagreement. According to this test, selectively neutral variation in gene frequencies should generate essentially homogeneous values of f for all loci, a homogeneity which can be tested by comparing the value of s f̂2 to a theoretical σ f̂2 expected when variations in f̂ are due solely to sampling error. The observed value of s f̂2 for the Atsera isolate is 2.9 × 10⁻⁵, which is not significantly different from the expected values that range from 1.23 × 10⁻⁵ to 2.46 × 10⁻⁵ depending on the constant used in calculating σ f̂2. Therefore it appears that nonselective aspects of population structure such as genetic drift and intervillage migration are responsible for the recorded genetic variation in this isolate.