Y-chromosome biallelic polymorphisms and Native American population structure.

It has been proposed that women had a higher migration rate than men throughout human evolutionary history. However, in a recent study of South American natives using mtDNA restriction fragment polymorphisms and Y-chromosome microsatellites we failed to detect a significant difference in estimates of migration rates between the sexes. As the high mutation rate of microsatellites might affect estimates of population structure, we now examine biallelic polymorphisms in both mtDNA and the Y-chromosome. Analyses of these markers in Amerinds from North, Central and South America agree with our previous findings in not supporting a higher migration rate for women in these populations. Furthermore, they underline the importance of genetic drift in the evolution of Amerinds and suggest the existence of a North to South gradient of increasing drift in the Americas.

Molecular epidemiology of hepatitis B virus in Afro-Venezuelan populations.

Hepatitis B virus (HBV) infection among Venezuelan populations of African origin was analyzed. These populations exhibited lower HBV prevalence than the one found in the African continent. Sequence analysis of 6 isolates showed that 3 belonged to genotype F, while the 3 others were HBV genotype A. HBV genotype A was more common in the Afro-Venezuelan groups than in the general Venezuelan population. This might reflect the introduction of genotype A during the slavery period. The absence of the African genotype E among these isolates supports the hypothesis of a recent origin for this HBV genotype. HBV genotype F has already been introduced to these relatively isolated communities.

Population structure of two black Venezuelan populations studied through their mating structure and other related variables.

In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population. Results agree with those previously obtained with traditional genetic polymorphisms and with the historical information available. Thus, the usefulness of surnames for inferring about population structure is supported, as well as the usefulness of historical information for explaining genetic diversity.

PIP: "In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population." (EXCERPT)

[The canarians of San Antonio de los altos, Edo, Miranda, Venezuela. Isolation and marriage unions between 1900 at 1981]. / Los canarios de San Antonio de Los Altos, Edo. Miranda, Venezuela. Aislamiento y uniones matrimoniales entre los años 1900 a 1981.

We present results of a study on isolation and endogamy in San Antonio de Los Altos a Venezuelan town founded in 1683 by 41 Spanish families of Canarian origin. The study was done with the civil marital records registered during the years 1905 to 1981. The results show that the same few surnames cover an important proportion of individuals in all the periods studied, which suggests that these belong to the traditional families. An important endogamy is revealed through the frequencies of surnames, birth places of spouses, and the isonymy analysis, which decrease after 1960 with the rupture of the isolate. The higher Fn values and the predominance of some types of isonymy suggests the existence of preferential unions. Geographic isolation and some economic factors, such as the property of the land, could have favoured the isonymy and endogamy observed among surnames of the founders of the town.

Genetic study in Panaquire, a Venezuelan population.

Panaquire is a population in Venezuela founded in 1733 by Spaniards from the Canary Islands. In order to define the genetic characteristics of this population the following loci were studied: ABO, RH (Cc, D, Ee), FY, K, JK, HB, ESD, ACP1, HP, TF, CP and ALB. Its sociohistorical features were also investigated. Historic censuses reveal that ethnically Blacks were the most important group in this village during the year 1800 (76%), followed by Amerindians (9%), Mulattoes (5%) and Whites (7%). The results of this analysis show that presently the most important genetic component is of African origin (59%), followed by Amerindian (26%) and Caucasian (15%) contributions. These results suggest that Canarians founded Panaquire, but unfavorable sociopolitical and environmental circumstances, as well as the entrance of former slaves, determined the village's evolution as a Black population. Important gene flow also occurred from Indian settlements, and some admixture with Whites. Our analysis shows once again the importance of handling together genetic and sociocultural variables to have a better interpretation of the evolution of human populations.

Comparison of two Venezuelan populations using the coefficient of relationship by isonymy.

The coefficient of relationship by isonymy Ri is a good indicator of similarities between and within populations by means of identity of surnames. In this study we present the results of an analysis of Ri obtained using two surnames for each person in two small Venezuelan populations of African origin: Birongo and La Sabana. The analyses of six Ri values within each population in two periods and of sixteen Ri values within each population between two periods and within each period between populations show that the higher values of Ri are those that include combinations of maternal surnames compared with any other combination and that in one period the relationship between Birongo and La Sabana was equal to 0, as measured with combinations of paternal surnames. These facts are indicators of a tendency toward matrifocal behavior and show that the use of four surnames for estimating Ri permits detailed comparisons of the relationship between and within groups.

Inbreeding as measured by isonymy in two Venezuelan populations and its relationship to other variables.

Isonymy is a useful approach to the study of population structure and thus can be utilized to detect deviations from random mating. In this study we give the results of an analysis of inbreeding levels and relate such variables as mean marital distance, surnames repeated in isonymous couples, and percentage of people using only maternal surnames to inbreeding and endogamy in two Venezuelan populations of black ancestry, Birongo and La Sabana. These populations differ in their sociocultural development and degree of isolation. We estimated inbreeding through isonymy and directly from genealogy. The most important findings are that the Ft values are higher than the a's, that the Fn component of Ft is higher than the Fr component, and that there is higher endogamy, inbreeding, and isolation in Birongo than in La Sabana. These results are in agreement with the sociocultural and historical background and development of each population. Nevertheless, both populations show similar temporal trends in almost all the variables analyzed. The use of isonymy as a complementary tool to study population structure is proposed, especially for Ibero-American populations.