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Valongo, an isolated Brazilian black community. I. structure of the population

Ilíada Rainha de Souza; Lodércio Culpi

Departamento de Genética, Setor de Ciéncias Biológicas, Universidade Federal do Paraná, Caixa Postal 19071, 81531 Curitiba, PR, Brasil. Send correspondence to L.C.

ABSTRACT

A Southern Brazilian isolated community of predominantly Black origin, with a total population of 81 individuals and a high degree of inbreeding was studied. Its inbreeding coefficient was equal to 0.048, a value that was still 3.5 times lower than that theoretically expected (0.1727) if consanguineous marriages had occurred at random. The inbreeding coefficient of the offspring of consaguineous couples was also very high: 0.069. The frequency of prenatal mortality was 11.2%; that of infant mortality, 9.0%; and that of twin births, 2.0%. The small sizes of the breeding (28), and of the effective (15) population, and the very small migration rate of the breeding population (7.1 %) suggest a high chance for the occurrence of genetic drift in this population, provided these conditions prevail for several generations.

Keywords: Valongo; Black community; Structure of tile population.

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