ANNALSOF HUMAN BIOLOGY, 2002, VOL. 29, NO. 5, 538±549 Populationstructure and genetic di erentiation among the substructured Vysyacaste population in comparison to theother populations of Andhra Pradesh,India N. Lakshmi , D. A. Demarchi‡, P. Veerraju and T. V. Rao y y y Departmentof HumanGenetics, Andhra University, Visakapatnam, India ‡ Departamentoy de Bioquõ ÂmicaClõ Ânica,Facultad de CienciasQuõ Âmicas,Universidad Nacional de Co Âr- doba, Co rdoba,Argentina Received20 December2000; in revised form 25 September2001; accepted 16 November2001 Summary. Objectives:Thepresent paper focuses on the study of the patterns of genetic microdierentiation among one of thesubstructured caste populations of AndhraPradesh, namelyVysya, with referenceto 17 otherTelugu speaking populations from thesame region of India. Subjectsand methods :Atotalof 302 individuals from thethree Vysya subgroups (101 of AryaVysya, 100 from KalingaVysya and 101 from Thrivarnika)were typed in 17 blood groupsand protein polymorphisms. Nei’s gene diversity analysis, as well asneighbour- joiningtree and UPGMA cluster diagrams, derived from standard genetic distances, R- matrixanalysis and a regressionmodel for investigatingthe patterns of external gene ¯ ow andgenetic drift dueto isolation under the island model, were done at two levels:(1) consideringonly the three Vysya populations and (2) considering common loci among 20 populationsof AndhraPradesh. Results:Sevenof the 17 systemsinvestigated were found to be monomorphicamong all the threeVysya groups. The UPGMA tree and bidimensional scaling of the D2 distances derivedfrom R-matrix analysis show averydistinct cluster of Vysya populations. Applica- tionof the model of regressionof averageheterozygosity versus the distance of populations from thecentroid shows thethree Vysya populations placed as clear outliers above the theoreticalregression line. Conclusions :Dierent approaches employed in this studygive support to the hypothesis of dierent origin and/ ordemographicstory for thethree Vysya groups compared with other populationsof AndhraPradesh. 1.Introduction India is aland of enormous human genetic, cultural and linguistic diversity (Roychoudhury, Roy, Dey et al. 2000).India issubdivided by20 major languages, hundreds of dialects, religion, almost innumerable castes and tribes, o ering a unique opportunity for the study of the process of subdivision and their evolutionary consequences (Puppala and Crawford 1996).The social structure of the Indian population is governed byhierarchical caste system. In the Hindu caste system, each caste belongs to one of the ®vemain classes/varnas,namely, Brahmins (priests), Kshatriya(warriors), Vyshya(business community), Sudra (rest of the castes) and Pancham (tribes). The caste structure is fairlyrigid, and each caste remains asan endogamous unit, although the levelsof endogamy varysubstantially (Malhotra and Vasulu1993). In India, there arenearly 5000 well-de® ned endogamous populations (Thangaraj,Ramana and LaljiSingh 1999).India is known for its unique population structure, which is characterized bysubdivision of its population into anumber of hierarchical caste, tribe and religious groups. These generalfeatures of population structure applyto each linguistic region of the country, whilelanguage forms a Annalsof Human Biology ISSN 0301±4460 print/ ISSN 1464±5033 online # 2002Taylor & FrancisLtd http://www.tandf.co.uk/journals DOI:10.1080/ 03014460110114707 Populationstructure amongthe Vysya caste 539 strong barrier to gene ¯owbetween such regions even among the castes of same or similar hierarchy. The State of Andhra Pradesh with its 70million people, organized into several endogamous castes, tribes and religious groups, presents enormous varietyof popu- lations, sociocultural patterns and organization. These castes and tribes arealso known to present extreme variationin size and nature of sub-structuring. Some of the major castes show number of endogamous subdivisions within them but with non-overlapping geographicdistributions. Furthermore, populations of Andhra Pradesh areknown to practise consanguineous marriageswith high rates of village endogamy.This willlead to reduction in e ective population size, creating breeding isolates within apparently single endogamous castes and subtribes. This willprovide situations conducive for rapid genetic microdi erentiation among such populations. Therefore, study of such substructured populations alongwith the others mayhelp inunderstanding the mechanisms behind the pattern of genetic variationobserved in aparticular region. The present paper focuses on the study of genetic microdi er- entiation among one of the substructured caste populations of Andhra Pradesh, namelyVysya, with reference to 17other populations from this Telugu-speaking Andhra Pradesh. 1.1.Population background The Vysyasare third in rank among the four-fold Hindu caste hierarchy, next to Brahmins and Kshatriyas. There arethree endogamous subcastes within them: the AryaVysyas, the KalingaVysyas and the Thrivarnikas.These populations belong to acommon stock, despite their separate caste identities and present sociocultural di erentiation (Sherring 1881).Of the three, the AryaVysyas are popularly known asGavara Komatis in Andhra Pradesh and with di erent synonyms such asAgarwal, Bania, Gupta, Chetty, etc. in other provinces of the country (Gupta 1988).They are a community of traders and businessmen, strict vegetariansin food habits, practise consanguineous marriagesand aredistributed mostly in towns and cities. The GavaraKomati occupy the highest position in the social hierarchy of the trading communities, followed byThrivarnikas, and KalingaKomati, the latter being regarded asthe lowest in the social scale. The KalingaVysyas live in the old Kalingacountry which extended roughly from Visakapatnamin Andhra Pradesh to contiguous areasin Orissa state. Theyare the second largestsection of Vysyas,their number running into severalthousands. Like the AryaVysyas, Kalinga Vysyas are known for trade and business enterprise as their core activity.Interestingly, they arenon-vegetarian bydiet, but practise con- sanguineous marriagesand worship deities belonging to both Vaishnaviteand Saivitesects, like the AryaVysyas do (Census of India 1981). Thrivarnikascall themselves asThrivarnika Vaishnavites. They claim that their community came into existence during 11thcentury ADatthe time of greater Vaishnavareformer Sri Ramanujacharya.There is, however, acontroversy regard- ingtheir origin. Theyfollow Brahminicalcustoms more scrupulously than others do, except that they arenon-vegetarians bydiet. The major economic resource for the Thrivarnikasis trade. Their principal occupation isbusiness in gold, silverand glass. Theyconsider themselves only next to AryaVysyas in social hierarchy. Although economically a‚uent, most of them haveonly informal education. Theyare found mostly in bigtowns and cities inAndhra Pradesh, besides alargenumber of families in Chennai. Their number is said to be in the vicinityof about 15000individuals. 540 N. Lakshmi et al. The Thrivarnikascan be identi®ed with their facialmarkings known as`namam’. Their namam is U-shaped with white and red markings. Theyare strictly anendo- gamous group. Theyattribute that their religious creed is distinct and in no way similar with Komati. Theydi er remarkably with the GavaraKomati inthe obser- vanceof various customary practices. The 17other Telugu-speaking populations for which comparative marker data were availableon seven common polymorphic loci, represent widesocio-economic network of the region. These populations represent upper castes like Brahmins; middle-ranking castes such asReddy, Kamma,Kapu; low-ranking castes such as Pattusali, Jalari,Bestha, Relli, etc.; traditionally untouchable scheduled castes such asMala and Madiga;and tribal group such asPardhi (Gopalam and Rao 1981, Naidu, Mohrenweiser and Neel 1985,K. P.Lakshmi, personal communication, Char,Lakshmi, Gopalam et al. 1989,S. Praveena,personal communication, Ramesh and Veerraju 1992,1996a, b, 2001). 2.Subjects and methods Atotal of 302blood samples werecollected from the unrelated adults of the three Vysyagroups (101of AryaVysya, 100 from KalingaVysya and 101from Thrivarnika) distributed in the three north coastal districts of Andhra Pradesh, namelyVisakapatnam, Vizianagaram and Srikakulam. Subjects were chosen only from the respective three municipalities of those three districts, except for Kalinga Vysyasfor whom the samples werealso collected from Bobbili municipality of Vizianagaramdistrict. About 3mL of blood wasdrawn byvenepuncture using disposable syringeinto sterile, labelled test tubes containing EDTA. The samples werestored in athermocol box containing ice and transported to the laboratory on the same day.Plasma and cells wereseparated. Plasmawas stored at 20°Cuntil use. One drop of packed cells wastaken to test A1A2BO and Rh (D) blood¡ groups on the same dayof collection. The remaining cells werehaemolised. The haemolysate wassubjected to electrophor- esis for G6PD and HBthe next dayas the G6PD enzyme isunstable. The remaining haemolysate wasstored at 20°C until use. Red cell enzymes weredetermined ¡ on starch and starch agarosegels. The methods opted for di erent systems were asfollows: 6PGD, G6PD, LDH and MDH (Harris and Hopkinson 1978);ACP and ESD (Karp and Sutton 1967);PGM2 and SOD (Spencer, Hopkinson and Harris 1964);glyoxalase (P¯ ugshaupt, Scherz and Butler 1978);haemoglobin (Bhatia1986). HP and CPweretyped bydisc gelelectrophoresis