Correlations of quantitative chromosomal heteromorphisms and classic genetic markers to demogeographic data in Garfagnana valley (Tuscany, Italy).

The genetic structure and interrelationships of six populations of the Garfagnana valley (Tuscany, Italy) were examined using chromosomal heteromorphisms concurrently with blood group system, red cell isozyme, and serum protein polymorphisms, secretor status, and surname frequency data. We aimed to evaluate the relationship of cytogenetic polymorphisms to more classical sources of gene frequency data in a population with a well-known demographic scenario. The R matrix technique (Harpending and Jenkins 1973) was used to estimate kinship coefficients, and the Harpending-Ward model (1982) and its extensions for quantitative traits (Relethford and Blangero 1990) were used to detect differential systematic pressure among population subdivisions. Mantel statistics were used to assess the significance of the correlations between cytogenetic, genetic, isonymy, geographic, and migration matrices. The analyses consistently gave similar results for the DA/DAPI cytogenetic heteromorphism and most gene frequency data. Both sets of results depend on migration patterns and on geographic distance among population subdivisions. However, C cytogenetic heteromorphism and some separately analyzed genetic markers did not fit the demogeographic pattern. Overall, it appears that data from different levels of the genetic hierarchy (namely, DNA regions encoding for classical biochemical markers and the noncoding highly variable cytogenetic bands of heterochromatin) can be treated and compared using the same analytical tools.