Endogamy among the Dogon of Boni, Mali

This paper examines factors influencing endogamy in a Dogon population in Mali. Situated in Boni district, this population of about 5000 individuals is distributed over fifteen villages located on four independent massifs. This population is strongly endogamous (only 4% of all marriages are contracted with neighbouring ethnic groups), and each massif shows high endogamy. The roles of lineage, residence in the same village, and geographical distance in mating choice are examined. These different factors are successively analysed using log-linear statistical models and the results offer a more precise interpretation of endogamy in this population.     

Evolution of marital structure in 20 Sardinian villages from 1800 to 1974

This paper reports the data for endogamy, exogamy and consanguinity in 20 Sardinian villages from 1800 to 1974, divided into generational periods (25 years). The data are taken from the records of 48,262 marriages celebrated in the parishes of 20 Sardinian villages. The results for Spearman's rank correlation coefficient indicate significant positive correlations of endogamy with consanguinity (r(s) = 0.6551, percentage of consanguineous marriages; r(s) = 0.5477, Bernstein's alpha), with altitude (r(s) = 0.6386), with population size (r(s) = 0.2519), as well as a significant negative correlation of endogamy with time (r(s) = -0.4210). In addition, consanguinity shows a significant positive correlation with altitude (r(s) = 0.5717, percentage of consanguineous marriages; r(s) = 0.6295, Bernstein's alpha) and a significant negative correlation with time (r(s) = -0.2363, percentage of consanguineous marriages); the negative correlation between the mean level of consanguinity (alpha) and time is statistically not significant. In the single parishes, the levels of endogamy and consanguinity are generally higher in the mountain villages than in those situated in the hill and plain areas. Finally, it is hypothesized that, in the time period considered, the level of consanguinity and especially of endogamy were largely determined by isolation.     

Ace Alu insertion polymorphism in Croatia and its isolates

Alu elements are a family of interspersed repeats in the genome propagating by retroposition into new chromosomal locations. Alu insertion in Ace gene is known to be polymorphic (presence/absence of Alu element) in worldwide populations and as such serves as marker for population structure analyses. In this study we examined the distribution of genotypes and allele frequencies of this polymorphism in general Croatian population and its two isolates (the island of Hvar and the coastal region of the Middle Dalmatia) and related them to the level of endogamy as an indicator of inbreeding in these populations. Results showed that these three population groups are different with respect to Ace Alu polymorphism. The endogamy was highest on the island of Hvar. With the increase of endogamy a decrease in heterozigosity was observed. The same trend was observed for the frequency of insertion allele. Its frequencies in the village subpopulations of two studied isolates are subject to genetic drift due to small population sizes and high levels of endogamy. This in turn causes genetic differentiation among villages that is observed to be higher on the island of Hvar than in the coastal region. In the worldwide perspective, the Ace Alu insertion allele frequency of 50.6% in the general Croatian population falls within the range of other European populations.     

Temporal trends in marital structure and isonymy in S. Paolo Albanese, Italy

In the fifteenth century, after the Turkish conquest of the Balkan area, Albanian communities migrated to Southern Italy. I investigated temporal trends in isolation from 1820 to 1982 in one of these communities, the population of S. Paolo Albanese, Basilicata, which still uses the original language and religious rites. Marital structure is characterized by a high average frequency of village endogamy (75.2%). Among the exogamous marriages there is a preference for mates from Italo-Albanian settlements, with higher values in the 1800s. The distribution of marital distances reflects the positive assortative mating by ethnic community. The mean frequency of isonymous marriages was 9.01% from 1820 to 1982. These results indicate that total inbreeding from isonymy is a reliable indicator of isolation, showing temporal trends related to changes in endogamy. Fr accounts for the greater percentage of Ft in relation to the small population size and regularly decreases with time. The breakdown of isolation, as documented by the decrease in population size, endogamy, and inbreeding, is a recent feature (since 1960).     

Population structure of the Indian people: some microevolutionary aspects

Some aspects of population structure, namely village endogamy, marital distance and consanguinity in India are discussed. These parameters show social and geographic variation. The role of culture is of great importance in determining the mating pattern of a population. In the Indian situation, group endogamy in general does not cause inbreeding. Consanguinity is a cultural phenomenon of long-standing tradition, and so far there is no strong indication of a temporal change.     

Genetic demographic characteristics of the rural population of the Tuva Republic: marriage structure and inbreeding]

Marriage structure was studied in three rural populations of the Tuva Republic: the Shinaan population and the populations of Todzhinskii and Bai-Taiginskii raions (districts). The Shinaan and Bai-Taiginskii populations had high levels of endogamy (0.6704 and 0.6050, respectively). In the Todzhinskii population, which was characterized by a mixed ethnic composition, endogamy was 0.3779 for the total population and 0.4626 for Tuvinians; interethnic marriages in this population were rare. The values of marriage assortativeness with respect to birthplace were 19.38, 40.75, 75.87, and 41.87% in the Shinaan, Bai-Taiginskii, all the Todzhinskii populations, and Tuvinian monoethnic marriages in the Todzhinskii raion, respectively. High marriage assortativeness with respect to ethnicity was found. Its values (A') were 91.85 and 93.49% in Tuvinians and Russians, respectively. Tuvinian populations were characterized by high inbreeding. The total (F(it)), random (Fst), and nonrandom inbreeding (Fis) estimated by isonymy were 0.004237, 0.002298, and 0.001944 in the Shinaan population, 0.007292, 0.009448, and -0.002177 in the Bai-Taiginskii population, and 0.003846, 0.004152, and -0.000307 in the Todzhinskii population, respectively (in the latter populations, the F(it), Fst, and Fis values for Tuvinian marriages alone were 0.005000, 0.007222, and -0.002238, respectively). The results obtained indicate that individual territorial groups of Tuvinians retain a high degree of genetic isolation from one another.     

Is the Central Valley of Costa Rica a genetic isolate?

In the last decade, the Costa Rican Central Valley population (CRCV), has received considerable scientific attention, attributed in part to a particularly interesting population structure. Two different and contradictory explanations have emerged: (1) An European-Amerindian-African admixed population, with some regional genetic heterocigosity and moderate degrees of consanguinity, similar to other Latin-American populations. (2) A genetic isolate, with a recent founder effect of European origin, genetically homogeneous, with a high intermarriage rate, and with a high degree of consanguinity. Extensive civil and religious documentation, since the settlement of the current population, allows wide genealogy and isonymy studies useful in the analysis of both hypotheses. This paper reviews temporal and spatial aspects of endogamy and consanguinity in the CRCV as a key to understand population history. The average inbreeding coefficients (a) between 1860 and 1969 show a general decrease within time. The consanguinity in the CRCV population is not homogeneous, and it is related to a variable geographic pattern. Results indicate that the endogamy frequencies are high but in general it was not correlated with a values. The general tendency shows a consanguinity decrease in time, and from rural to urban communities, repeating the tendencies observed in other countries with the same degree of development, and follows the general Western World tendency. Few human areas or communities in the world can be considered true genetic isolates. As shown, during last century, the CRCV population has had consanguinity values that definitively do not match those of true genetic isolates. A clear knowledge of the Costa Rican population genetic structure is needed to explain the origin of genetic diseases and its implications to the health system.     

Ethnicity and malaria affect surname distribution in consenza Province (Italy)

Three samples of surnames reported in the telephone directory of Cosenza province, Italy, are used, singly and together, to detect the presence of genetic barriers and to analyze the genetic relationship between the Italian and the Italo-Albanian communities living in this area. The genetic structure of the population seems characterized by the distinction between the northern and southern regions of the province. The Sibari plain, endemic with malaria until recently, probably constituted a genetic barrier. In the southern region of the province, the valley along the Crati river (also occupied by malarial fenlands), constituted a genetic barrier between the northern Sila upland and the western coast. Surname similarities between Italians and Italo-Albanians could be the result of gene flow and/or an initial choice of similar surnames; the second possibility accords with the persistence of the Albanian cultural identity and the level of endogamy in Albanian communities. In fact, the coefficient of relationship by isonomy (Ri), which is significantly higher in Italo-Albanians than in Italians, may be the result of genetic isolation and endogamy.     

Isonymic analysis of population structure in Gredos, Spain

For the period 1875-1975 an isonymic analysis was made based on 41,696 marriages celebrated in three valleys (Tormes, Alberche and Tietar) from Gredos (Spain). Total inbreeding (Ft) was lower in the Tietar valley (0.0103- 0.0136), followed by the Tormes (0.0125-0.0255) and the Alberche (0.0153-0.0200). In the latter, random inbreeding (Fr) surpassed non random (Fn). Correlation coefficients were obtained to confirm an association of inbreeding from isonymy with valley and village endogamy rates, locality census, altitude, and alpha inbreeding. Fn correlated positively with average valley endogamy and village endogamy and with altitude, but inversely with census size. Contrarily, Fr related significantly to village endogamy. The non-random component from isonymy related positively to inbreeding from dispensations. Except for village endogamy, both variables show the same relationships to variables, such as altitude, which reflect limitations to mobility; or valley endogamy indicating the disposability of potential mates which in turn depends on the census size.     

Russians of the Karachay-Cherkess Republic: Population Genetic Portrait

To describe the population-genetic structure of the Russian population of Karachay-Cherkessia, the database of Compulsory Medical Insurance and marriage records for 1990–2000 were used. The Russian population is characterized by a low birth rate, low endogamy, low inbreeding, and a high level of miscegenation.     

Class endogamy, inbreeding and migration during the Argentinean colonial period: analysis based on individuals of European ancestry

During the Spanish colonial period, Córdoba was an important town due to its location suitable for controlling communication throughout a wide region of Argentina. As a typical colonial society, where individuals belonged to a well established social class, marriages among Whites were the result of strict norms and prejudices founded on nets of kinship, friendship and neighbouring. The objective of this paper is to determine, whether the elevated class endogamy among Whites during the colonial period resulted in high consanguinity and whether a process of selection of surnames was present in 1813. In both cases the interaction with the migratory flow was taken into account. It is concluded that (a) Although an endogamy of "class" existed among Whites, there is no evidence of the consequences on the biological structure of the population through preferential mating between relatives, as deduced from the low level of inbreeding from isonymy. (b) There was no differential reproduction reflecting the selection of families carrying certain surnames; therefore surnames followed a "neutral" model. (c) The diversity of surnames and the gene flow deduced from them were of a magnitude similar to present populations; this fact could have balanced the effect of the "class" endogamy. (d) Finally, the congruence between information derived from the population age distribution and historic data and the quantification of migration from surnames allowed the detection of mistakes in the census data file regarding the number of foreigners, thus validating the use of surnames as biological markers of the population structure.     

Inbreeding and surnames: a projection into Easter Island's past

The population of Easter Island is one of the most interesting extant human communities due to its unique demographic history, its geographic isolation, and the development of an incomparable culture characterized by the towering "Moais" and its enigmatic writing. Following the colonization of its population by Polynesians from the Mangarevan Islands in the 5th century AD, the island remained isolated up until the middle of the 20th century. Under these conditions, with endogamy levels fluctuating between 61.04-96.54% and given such a small population, a high rate of inbreeding, and consequently, an elevated level of genetic relationships would be expected. Using data from church and civil records, we calculated the consanguinity of the population of Rapa Nui. The results of this analysis do not support the hypothesis of a high level of consanguinity (alpha = 0.00028 and F(t) = 0.0007, with F(r) = 0.00586 and F(n) = -0.00519), suggesting instead the existence of a strategy used to avoid marriage between close relatives. To explain these observations, the structure and exchange dynamics of the population were studied in the tribes, known locally as "Mata." The results of this analysis suggest a tendency toward the avoidance of inbreeding within tribes, in order to decrease the rate of endogamy in each group. This is consistent with ethnographic observations from the beginning of the 20th century that support the existence of strict regulations to prevent inbreeding between closely related individuals. Furthermore, we confirm that this situation dates back to a period before the "refounding" of Easter Island. Our results demonstrate that conditions of geographical isolation are not in themselves sufficient to produce an elevated inbreeding coefficient, revealing Easter Island as an interesting example of how cultural rules can shape the genetic structure of a population.     

Endogamy index and its changes with time in some populations of the Volga-Ural region

Data on several populations of Russia have been used to demonstrate that the change in the endogamy index detected in the second half of the 20th century is not global. Migration activity remains high in populations with relatively low endogamy indices, and their endogamy does not change with time. In regions with medium and high endogamy indices, these values also tend to remain stable. The endogamy indices of urban populations are increasing, and those of rural populations are decreasing.     

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.     

Endogamy index and its changes with time in some populations of the Volga-Ural region

Data on several populations of Russia have been used to demonstrate that the change in the endogamy index detected in the second half of the 20th century is not global. Migration activity remains high in populations with relatively low endogamy indices, and their endogamy does not change with time. In regions with medium and high endogamy indices, these values also tend to remain stable. The endogamy indices of urban populations are increasing, and those of rural populations are decreasing.     

Medical genetic research on the Khanty population of the Ovgort rural district of the Yamal-Nenets Autonomous territory

The results of medico-genetical studies of the Khanty from the Lower Ob river carried out by Tomsk Department of Institute of Medical Genetics of Academy of Medical Sciences of the USSR are presented. The population is characterized by a relatively high index of endogamy (0.54) and a low inbreeding coefficient (0.0011). Diseases of the polygenic mode of inheritance predominate among nosological forms of hereditary pathology.     

Impact of restricted marital practices on genetic variation in an endogamous Gujarati group

Recent studies have examined the influence on patterns of human genetic variation of a variety of cultural practices. In India, centuries‐old marriage customs have introduced extensive social structuring into the contemporary population, potentially with significant consequences for genetic variation. Social stratification in India is evident as social classes that are defined by endogamous groups known as castes. Within a caste, there exist endogamous groups known as gols (marriage circles), each of which comprises a small number of exogamous gotra (lineages). Thus, while consanguinity is strictly avoided and some randomness in mate selection occurs within the gol, gene flow is limited with groups outside the gol. Gujarati Patels practice this form of “exogamic endogamy.” We have analyzed genetic variation in one such group of Gujarati Patels, the Chha Gaam Patels (CGP), who comprise individuals from six villages. Population structure analysis of 1,200 autosomal loci offers support for the existence of distinctive multilocus genotypes in the CGP with respect to both non‐Gujaratis and other Gujaratis, and indicates that CGP individuals are genetically very similar. Analysis of Y‐chromosomal and mitochondrial haplotypes provides support for both patrilocal and patrilineal practices within the gol, and a low‐level of female gene flow into the gol. Our study illustrates how the practice of gol endogamy has introduced fine‐scale genetic structure into the population of India, and contributes more generally to an understanding of the way in which marriage practices affect patterns of genetic variation. Am J PhyAnthropol 2012. © Wiley Periodicals, Inc.     

The effect of marriage migration on the genetic structure of the Taimyr Nganasan population: genealogical analysis inferred from MtDNA markers

The marriage structure of Nganasans during the time period from 1796 to 1991 and genealogy of carriers of mitochondrial DNA haplotypes was studied in a sample of 280 individuals. It was shown that, from the beginning of its formation to the late 1970s, the population exhibited high endogamy (1976, 83.8%; 1926, 88.4%; 1976, 74.3%). The main source of traditional marriage migration (preferentially female) was populations of Entsy and, indirectly, Nentsy. Intense assimilation of Nganasans by the immigrant population, and to a lesser extent, by Dolgans, in the second half of the 20th century resulted in a reduction of endogamy index in Avam Nganasans to 42.5% by 1991. Assimilation by the immigrants was predominantly paternal, promoting preservation of the historically formed genetic diversity of the Nganasan mitochondrial gene pool. Genealogical analysis of mtDNA haplotypes showed that a relatively high total frequency of Western Eurasian mtDNA haplogroups (20.4%) in the Mongoloid (according to anthropological type) Nganasan population is explained not only by the common ethnic origin with Entsy and Nentsy, but also by direct marriage migration from the Entsy population and indirect marriage migration, from the Nentsy population. This migration led to accumulation of Entsy-Nentsy maternal lineages in the genealogy of Avam Nganasans (38.9% of the total number). Of all mtDNA haplotypes, 28.6% were introduced to Avam Nganasans by female Entsy and Nentsy, whereas the total frequency of these haplotypes was 0.204. Genetic diversity of mitochondrial DNA haplotypes was 0.935.     

Social structure and consanguinity in a French mountain Population (1550-1849)

Sociocultural factors play a crucial role in the variation of consanguinity in a population. The choice of specific matrimonial strategies can favor the closure or opening of the group to the outside, whereas differential fertility affects the gene flow from one generation to another. In the present study we analyzed the role of socioprofessional groups in the maintenance of endogamy and consanguinity in a French Alpine valley: Vallouise in the Brian?on area. In mountain environments, where the reproductive space is limited and quickly saturated, the autochthonous families adopt diversified matrimonial strategies. These marriage practices tend to prevent fragmentation of agricultural property. We analyzed the matrimonial behavior in the two main social groups of this population (décideurs and farmers) from 1550 to 1849. To better understand the behavior of the two social groups, we considered the two components of consanguinity, close and distant. Our study showed that the two groups had similar behavior regarding consanguinity. The way to prevent fragmentation of the patrimony was to choose a consanguineous spouse. This type of strategy inevitably leads to a high percentage of endogamy, which in this region of the Alps exceeded 90% through many centuries.     

Genetic diversity of <Emphasis Type="Italic">Parides ascanius</Emphasis> (Lepidoptera: Papilionidae: Troidini): implications for the conservation of Brazil’s most iconic endangered invertebrate species

Parides ascanius (Lepidoptera: Papilionidae) is a butterfly endemic to the sand forests (“restingas”) of one of the most populated areas of Brazil (from Rio de Janeiro state to South Espírito Santo state), and was the first invertebrate officially recognized as being threatened in Brazil. Here we present a panel of eight polymorphic microsatellite loci and partial sequences of mitochondrial gene COI aiming to characterize this butterfly’s genetic diversity and understand its distribution among the extant populations. We estimate F_ST metrics, migration rates, cluster assignment, and spatial structure of genetic diversity. F_ST and statistics indicate low genetic structure and no evidence for endogamy, with all populations connected by high migration rates. Seven populations have low permanence rates (68–75 %) with increased migration probabilities for all populations. One population displays higher permanence rate (87.7 %), as the metropolitan matrix isolates it. Spatial analysis shows a global structure around the city of Rio de Janeiro and the Guanabara Bay; assignment analysis recovers six clusters evenly spread among sampled populations. These findings are consistent with a natural scenario of metapopulation dynamics for P. ascanius, with low genetic diversity and no endogamy, but progressively isolated by the metropolitan matrix. Conservation efforts should focus in connecting the isolated population, broaden the searches for new populations, and preserve all extant habitat patches where P. ascanius still occurs.