Demographic structure and microevolution of an Italian alpine isolated population

Area of Science:

• Population genetics
• Demographic analysis
• Human microevolution

Background:

• The isonymic method uses surnames as proxies for genetic markers to study population dynamics.
• Postua, a North Western Italian mountain village, offers a unique case study due to historical isolation and consanguinity.

Observation:

• The study analyzed demographic parameters in Postua from 1640 to 1989, including endogamy, isonimy, and consanguinity rates.
• High endogamy (80-90%) and isonimy (up to 34.4%) characterized Postua until the mid-19th century, indicating a closed community.
• Significant immigration in the 20th century led to reduced isolation and increased surname diversity.

Findings:

• Postua experienced population fluctuations, with peaks in the late 18th and late 19th centuries.
• Surname frequency remained stable until the mid-19th century, after which founder surnames declined and new ones emerged.
• The S/N ratio, initially low, increased significantly in the late 20th century due to immigration.

Implications:

• Surnames effectively tracked microevolutionary changes in Postua, reflecting shifts from isolation to openness.
• Demographic methods combined with isonymy provide insights into the genetic history of isolated populations.
• Understanding historical demographic patterns is crucial for interpreting contemporary population genetic structures.