Background: The study is part of a research project on the marital structure of mountain populations from the Eastern Italian Alps. Little is known about marriage patterns in this Alpine area.
Aim: The aim of the study is to evaluate the extent of reproductive isolation in some communities of the Non Valley (Trentino, Italy) and to investigate its microgeographic and temporal changes over the period 1825-1923.
Subjects and methods: 4518 microfilmed marriage records from registers of seven parishes of the Non Valley were used to analyse the following: endogamy rate, inbreeding calculated both from dispensations and from isonymy, repeating pairs of surnames in marriages, isonymic relationships.
Results: The results show notable variability among parishes in the levels of endogamy (40-73%), inbreeding (alpha: 1.9-4.57; Ft: 0.0073-0.019) and subdivision (RPr/RP: 0.5-1.3). The values are relatively stable over the course of a century, apart from a rise in inbreeding indicated by dispensations and a slight decrease of endogamy at the beginning of the 20th century. Isonymic relationships reflect geographic proximity between populations, with minimum changes through time.
Conclusions: Variations in the level of reproductive isolation within the Non Valley are consistent with the different geographic characteristics and population sizes of the settlements. Comparison with data obtained from previous studies in the Eastern Italian Alps shows that the values of the investigated biodemographic indicators are in line with the geography and altitude of the area. The slight differences in temporal trend of endogamy and inbreeding can be correlated with different migration patterns.