Relationships by isonymy between persons with monophyletic and polyphyletic surnames from the Monterrey metropolitan area, Mexico.

Three thousand two hundred eleven males and females who resided and were interviewed in the Monterrey metropolitan area in northeastern México were selected for having 1 of 10 common selected surnames as either their patronymic or matronymic name. Five of the names are considered monophyletic and five are considered polyphyletic. Because each individual has two surnames, information about the name complementary to the selected surname was analyzed using isonymy methods (1) to see the effect of immigration on the genetic composition of the population and (2) to determine the isonymy, the relationship by isonymy within and between the persons with monophyletic and polyphyletic surnames. The percentages of the most common complementary surnames, the coefficients of relationship by isonymy of surnames for a selected surname, and the coefficients of relationship between the selected surnames are higher in the monophyletic than in the polyphyletic surnames, indicating that the persons with monophyletic names still conserve some customs of the founders that possibly increase their degree of endogamy. Perhaps these indicators are inversely related to migration, indicating that the monophyletic surnames have been more stable in Monterrey since it was colonized.