Isonymic analysis of population structure in Gredos, Spain

Area of Science:

• Population Genetics
• Human Genetics
• Anthropology

Background:

• Isonymy, the study of shared surnames, offers insights into population structure and mating patterns.
• Historical demographic data, like marriage records, are crucial for understanding long-term genetic relationships.

Purpose of the Study:

• To analyze total inbreeding (Ft) and its components (random Fr, non-random Fn) in three Spanish valleys from 1875-1975.
• To investigate the correlation between isonymy-derived inbreeding and factors like endogamy, population size, and altitude.

Main Methods:

• Isonymic analysis of 41,696 marriages across Tormes, Alberche, and Tietar valleys.
• Calculation of total (Ft), random (Fr), and non-random (Fn) inbreeding coefficients.
• Correlation analysis with endogamy rates, census data, altitude, and inbreeding from dispensations.

Main Results:

• Tietar valley exhibited the lowest total inbreeding (Ft), followed by Tormes and Alberche.
• In the Alberche valley, random inbreeding (Fr) exceeded non-random inbreeding (Fn).
• Non-random inbreeding (Fn) correlated positively with endogamy and altitude, and inversely with population size.

Conclusions:

• Geographic and social factors significantly influence inbreeding patterns and mating networks.
• Altitude and endogamy rates, reflecting mobility limitations and mate availability, are key determinants of non-random inbreeding.
• Isonymy provides a valuable tool for reconstructing historical population genetic structures.