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Arriere-plan: Les polymorphismes de l'ADN mitochondrial ont fait la preuve de leur utilite pour l'etude des origines et des parentes genetiques. Les origines des populations castees de l'Inde sont restees enigmatiques et les apparentements genetiques des castes ne sont pas uniformes d'une region geographique a une autre. But: Cette etude a ete entreprises pour analyser la nature et l'etendue des variations d'ADNmt ainsi que les relations des groupes castes de l'etat indien occidental du Maharashtra et pour examiner ce que les resultats impliquent quant a leurs origines. Sujets et methodes: Une population a ete selectionnee dans chacune des trois castes et des echantillons sanguins ont ete obtenus de sujets non apparentes pleinement informes du but de l'etude. Les populations ordonnees en castes etaient : le rang superieur (Brahmane; n = 31), rang moyen (Maratha; n = 41) et le rang inferieur (Nava Baudh; n = 40). On a etudie les polymorphismes de dix sites de restriction (RSPs) et d'un locus d'insertion/deletion (InDel). Le segment hypervariable 1 (SHV1) a ete sequence a partir d'un sous-ensemble des individus echantillonnes. Resultats: Quatre loci RSPs ont ete trouves monomorphiques dans les trois populations. Le locus InDel est monomorphique dans deux d'entre-elles (Brahmane et Maratha). Un haplotype construit sur la base des RSPs est predominant dans les trois groupes. La diversite haplotypique est de magnitude similaire chez les Maratha et les Nava Baudh (respectivement 68% et 64%), nettement plus elevee que chez les brahmanes (49%). La frequence de l'haplogroupe M est elevee dans les trois groupes, mais contrairement a ce qui etait attendu, elle est plus haute chez les brahmanes. Pres de 10% des brahmanes cependant portent l'haplogroupe C. Une large variation a ete trouvee dans la region du SHV1. Les diversites nucleotidiques et le nombre moyen de non appariements, ont une magnitude semblable dans les trois groupes. Conclusions: La caste superieure Brahmane est genetiquement distincte des castes moyenne et inferieure; cependant, sa frequence plus elevee de l'haplogroupe M, laisse penser qu'elle aurait pu recevoir des apports de population externes.

SummaryThe theoretical justifications for using the number of rare alleles observed in a sample and the heterozygosity contributed by such alleles to estimate the relative electrophoretic mutation rate (REMR) are given in this note. It is shown that the estimator using the number of alleles has comparatively less bias. While the total heterozygosity contributed by all alleles at a locus has been previously used to estimate REMR with success, an analogous estimator with ony rare alleles has large bias over a wide range of effective population size and sample size.

Phenotype and gene frequencies for four blood group systems (ABO, MN, Rh and P) and haptoglobin among five endogamous groups of Delhi, India, are reported. All the systems are polymorphic in all the population groups. The average heterozygosity per locus in high (in the range 48-52 per cent) for all the groups. The extent of genic variability among the groups in terms of net codon differences per locus has been studied; the heterogeneity within the groups is large as compared to the between-group heterogeneity. There is no definite clustering of the of the groups with respect to their biological rank.

Data on the distance between the birthplaces of spouses (matrimonial distance) were collected from 2,260 married individuals belonging to 21 endogamous castes of the Dhangar (shepherd) cast-cluster of Maharashtra, India. The general form of the distribution of matrimonial distances is one which is extremely positively skewed and leptokurtic. The percentage of intra-village marriages generally decreases from the southern areas of Maharashtra to the northern areas of the state, as does the inbreeding coefficient. This situation is in conformity with the socio-cultural norms regulating matrimonial choice in south and north India. An attempt has been made to relate the degree of inbreeding to the mean matrimonial distance and population size. The mean matrimonial distance is more useful in predicting the degree of inbreeding than population size.Data on the distance between the birthplaces of spouses - matrimonial distance - were collected from 2260 married individuals belonging to 21 endogamous castes of the Dhangar (shepherd) caste-cluster of Maharashtra, India. The data are analyzed with a view to finding differences in the distributions of matrimonial distances among the caste groups, and to examine the relationship of the inbreeding coefficients of these gorups with their mean matrimonial distances and population sizes. The general form of the distribution of matrimonial distances is one which is extremely positively skewed and leptokurtic. The percentage of intra-village marriages generally decreases from the southern areas of Maharashtra to the northern areas of the state, as does the inbreeding coefficient. Further examination is made of the differences in matrimonial differences and inbreeding coefficients in terms of sociocultural norms regulating choice of mates, geographic dispersal of population, and migrational history, concluding that the situation is in conformity with norms prevailing in south and north India. In an attempt to relate the degree of inbreeding to the mean matrimonial distance and population size, it was found that the former is more useful in predicting the degree of inbreeding than population size.