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 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

Sonia Colantonio

Vicente Fuster

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Coll. Antropol. 30 (2006) 1: 199–203Original scientific paperIsonymic Analysis of Population Structurein Gredos, SpainVicente Fuster1 and Sonia Colantonio21 Department of Zoology and Physical Anthropology, University Complutense of Madrid, Madrid, Spain2 Department of Physiology, National University of Córdoba and CONICET, Córdoba, ArgentineA B S T R A C TFor 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) sur-passed non random (Fn). Correlation coefficients were obtained to confirm an association of inbreeding from isonymywith valley and village endogamy rates, locality census, altitude, and  inbreeding. Fn correlated positively with averagevalley endogamy and village endogamy and with altitude, but inversely with census size. Contrarily, Fr related signifi-cantly to village endogamy. The non-random component from isonymy related positively to inbreeding from dispensa-tions. Except for village endogamy, both variables show the same relationships to variables, such as altitude, which re-flect limitations to mobility; or valley endogamy indicating the disposability of potential mates which in turn depends onthe census size.Key words: surnames, isonymy, inbreeding, Gredos, SpainIntroductionIt is possible to establish the influence of limited mo-bility on population genetic structure by using surnameswhich allow the study of inbreeding levels following theCrow and Mange1 method and the inter-popula- tion re-lationship of Lasker2.The Spanish system of surname transmission includ-es two names (paternal and maternal). Schematic repre-sentations of this system are reported by several au-thors3,4. Shaw5 was the first to indicate the advantages ofthis system, which Lasker6 summarized by doubling thenumber of surnames and distinguishing between pat-rilineal and matrilineal kinship.Sierra de Gredos is restricted to the province of Avilaand occupies a surface of 2,400 Km2. The Tormes and theAlberche valleys are located at the northern slope, whilethe southern slope (Tietar Valley) opens onto the Casti-lian Plateau, which extends throughout most of centralSpain (See Fuster et al.7, for a map).Marriages celebrated between 1875–1975 in 48 par-ishes consisting of 40 municipalities (9 of which belong tothe Tormes, 13 to the Alberche and 18 to the Tietar val-ley) were analyzed. The 1877–1970 mean number of in-habitants was 7,117, 18,331 and 35,113 respectively. From1960 onwards, emigration towards more developed re-gions has taken place, contributing to a census decreasein some localities. Agriculture predominates in Gredos,though besides a modest forest industry, tourism has re-cently been developed in several villages.The Sierra de Gredos, with a maximum altitude of2,600 m and only three north-south natural passes, haslimited mobility among valleys. Gredos valley heteroge-neity regarding altitude, census size and marital endog-amy justify an analysis of inbreeding by isonymy per val-ley. Supplementing previous studies of the migrationpattern and of consanguinity7,8, the present research ex-plores the intra and inter-valley variation of the diversecomponents of kinship, including their temporal change.Materials and MethodsA sample of 41,696 weddings, celebrated in three val-leys (Tormes, Alberche and Tietar) from the Gredosmountain range, provided information consisting of 4surnames per couple.199Received for publication January 20, 2005Instead of the usual analysis according to weddingplace, data for the present research were organized bymeans of the groom’s place of residence which, in mostcases, corresponds to the locality of reproduction. Mar-riages were assigned to any of the three valleys consid-ered, and families whose reproduction was expected tooccur in localities external to any of the 40 municipalitiesbelonging to the Gredos valleys were not taken into ac-count.Total inbreeding from isonymy (Ft) can be directlycalculated from marital isonymy. The contribution ofrandom (Fr) to the total inbreeding coefficient (Ft) wasdetermined by the distribution of surnames, while thenon random inbreeding (Fn), due to other factors, suchas tendency for mating among relatives, was estimatedfrom Ft and Fr. Since in Spain two surnames are takenby any individual (the first given by the father and thesecond by the mother), the expected random isonymyand the corresponding Fr inbreeding coefficients werecalculated according to the Pinto-Cisternas et al.3 me-thod, a modification of the Crow and Mange1 prior proce-dure which considers only one surname per individual.Fr is defined as (pi1qi3 + pi1qi4 + pi2qi3 + pi2qi4)/4,where pi represents the frequency of surname i amonghusbands and qi among wives; 1 to 4 indicates the sur-name origin (1 and 3 paternal, 2 and 4 maternal). Accord-ing to Pinto-Cisternas et al.3 Fr, Fn and F are homolo-gous to FST, FIS and FIT in Wright´s nomenclature, respec-tively. The first notation was preferred in this paper dueto its frequent use in inbreeding studies by isonymy9–12.Each valley census size per period corresponds to thenumber of inhabitants at the central year of the period.Valley and village endogamy rates were obtained accord-ing to the proportion of husbands and wives born thesame valley or village, respectively.Results and DiscussionThe Gredos valleys are heterogeneous regarding theaverage size and altitude of villages as well as endogamyrates, both calculated by village or by valley (Table 1). Ir-respective of period, the highest percentage of intra-val-ley marriages occurred in the Tormes, but for village en-dogamy, these occurred only during the two last periods(1935 to 1975). In this valley a much reduced number ofvillage inhabitants may have limited endogamous mar-riages. However, the Tormes valley, as a whole, couldhave provided enough potential mates to cause an ele-vated intra-valley endogamy rate.In Table 2 are shown the results corresponding to thethree components of the inbreeding coefficient obtainedfor the periods considered. For comparison purposes theinbreeding coefficient from dispensations () is included,although the fact should be kept in mind that surnamesoverestimate inbreeding, as reported by several authors13–15.Regarding temporal variations of the inbreeding compo-nents estimated from isonymy, no clear pattern wasfound. The only noticeable result corresponds to highervalues of inbreeding by isonymy between 1915 and 1954,a variation similar to that of the inbreeding coefficientestimated from ecclesiastical dispensations7. In absoluteterms, maximum inbreeding (both from dispensationsand from surnames) corresponds to the Tormes and min-imum to the Tietar, the Alberche having intermediatevalues, but closer to the Tietar than to the Tormes,mainly in the case of dispensations.Considering inter-valley variation, Ft coefficients areslightly lower in the Tietar valley (0.0103–0.0136), fol-lowed by the Tormes (0.0125–0.0255) and the Alberche(0.0153–0.0200). In the Alberche valley Fr always sur-passes Fn, while Fn predominates in the Tormes. Asshown in Table 1, the Alberche valley has higher villageendogamy, regardless of period (Table 1). On the con-V. Fuster and S. Colantonio: Isonymic Analysis in Gredos, Spain, Coll. Antropol. 30 (2006) 1: 199–203200TABLE 1AVERAGE VILLAGE CENSUS, WEIGHTED ALTITUDE AND ENDOGAMY PER VALLEY AND PERIODPeriodAverage census and altitude (m) EndogamytypeTormes Alberche TietarTormes Alberche Tietar N ER (%) N ER (%) N ER (%)1875–1894 572 1129 1518 696 94.68 2049 88.58 4416 83.561895–1914 648 1251 1739 787 95.68 2758 84.45 4696 85.351915–1934 652 1416 1924 Valley 703 93.74 3077 86.81 4727 86.841935–1954 646 1498 2235 endogamy 619 94.67 2497 85.06 4621 84.981955–1975 502 1363 2047 380 93.42 2153 81.56 3945 90.141875–1894 1295 993 661 696 73.13 2049 81.60 4416 75.571895–1914 1290 971 655 Village 787 75.73 2758 78.79 4696 76.721915–1934 1277 959 644 endogamy 703 78.81 3077 82.35 4727 77.391935–1954 1277 972 634 619 78.84 2497 77.57 4621 74.571955–1975 1285 952 625 380 79.74 2153 74.41 3945 68.95Total 3185 12534 22405ER – valley and village endogamy rates in %, N – number of marriages, endogamy rates obtained considering valley and village as thepopulation unitstrary, the Tormes has always maximum valley endogamy,indicating that valley endogamy could be related to Fn,and Fr to village endogamy. The reduced village sizes inthe Tormes would have limited the number of potentialmates, thus encouraging the establishment of couplesamong inhabitants of the valley, while in the Alberchemore marriages could have taken place within each vil-lage.Regarding the above results, each valley differentialcensus size was taken into account. In the Tormes valley,the combination of small village size, maximum altitudesand therefore greater geographical isolation, could be ex-pected to have produced high F coefficients but, on thecontrary, low coefficients in the Tietar (larger villagesize, minimum altitudes and lower geographical isola-tion). Furthermore, according to Relethford16,17, a differ-ent total number of surnames may affect the resultssince Fr is expected to be smaller in large populations, aresult which is true for the Tietar.Correlation coefficients between variables were ob-tained to confirm whether Fr and Fn differences can berelated to the endogamy rates both at valley and villagelevels, average locality census per valley and weighted al-titude. Correlations with the  inbreeding coefficient ob-tained from ecclesiastical dispensations (Table 2, right)were also calculated. Because several of these variablesdo not fit a normal distribution, a non parametric corre-lation was applied (Table 3).The most frequent significant correlations for thevariables shown in Table 3 exist for Fn. Fn related posi-tively to the average valley endogamy and village endo-gamy, as well as to altitude and  coefficient, and in-versely to census size. The inbreeding from dispensations(), with the exception of village endogamy, showed thesame association with the remaining variables.The positive correlation between Fn and altitude, andnegative with village size, is in agreement with the rela-tionship between  and the same variables found in a re-view based on published inbreeding data from ecclesias-tical dispensations18.Contrarily, Fr relates significantly to village endog-amy, but not to valley endogamy, census or altitude. Thelowest correlation coefficients were found between valleyand village endogamy rates (0.143) and between Fr andvalley endogamy (–0.182), suggesting that in Gredos ran-dom factors affecting marriages are restricted to villagelevel. The non-random component of inbreeding esti-mated from isonymy (Fn) may represent marriages be-tween relatives, but Fr concerns only village endogamy.Valley endogamy correlates negatively to the averagenumber of village inhabitants in each valley (–0.600,p<0.05) but that of village does not correlate signifi-cantly. The negative significant correlation existing be-tween Fn and the average village census is concordantwith the availability of non-related mates in each village.Finally, altitude correlates significantly with all fac-tors other than village endogamy and Fr: at highest alti-tude villages are smaller, and larger preferential inbreed-ing exists among valley localities.In Gredos the marital migration pattern was charac-terized by north-south mobility restriction8. The south-ern Gredos slope (Tietar) was more open to immigrantsfrom areas outside the other two valleys, which is inagreement with the geographical characteristics of thisV. Fuster and S. Colantonio: Isonymic Analysis in Gredos, Spain, Coll. Antropol. 30 (2006) 1: 199–203201TABLE 2RANDOM (Fr), NON-RANDOM (Fn) AND TOTAL COEFFICIENTS (Ft) OF INBREEDING BY ISONYMY AND INBREEDINGCOEFFICIENT (), PER VALLEY AND PERIODValley Period Fr Fn Ft 1875–1894 0.00474903 0.00777703 0.01248913 0.00260421895–1914 0.00563163 0.01091722 0.01648736 0.0035538Tormes 1915–1934 0.00584351 0.01141036 0.01718720 0.00413411935–1954 0.00623901 0.01937383 0.02549196 0.00416501955–1975 0.00589752 0.01461041 0.02042176 0.00172701875–1894 0.01060138 0.00946349 0.01996455 0.00070921895–1914 0.00882281 0.00778167 0.01653583 0.0008158Alberche 1915–1934 0.00899769 0.00795547 0.01688158 0.00120861935–1954 0.00895069 0.00778261 0.01666364 0.00107631955–1975 0.00829833 0.00707533 0.01531495 0.00013791875–1894 0.00482928 0.00548212 0.01028493 0.00077491895–1914 0.00536417 0.00652434 0.01185351 0.0007952Tietar 1915–1934 0.00535274 0.00833751 0.01364562 0.00144121935–1954 0.00544131 0.00683997 0.01224406 0.00104481955–1975 0.00525514 0.00554023 0.01076625 0.0002812Inbreeding coefficient  calculated from ecclesiastical dispensations, up to third degreemountain range, the Tormes valley located at a higher al-titude than the Tietar. In terms of surname variation,the smaller Fr and Fn coefficients correspond to theTietar. In addition, each valley population size and en-dogamy are reflected in the distribution of surnames,mainly affecting the Ft and Fn coefficients, while Frshows a less differentiated pattern.The correlation coefficients obtained in the presentanalysis confirm that inbreeding relates positively to thenon-random component from isonymy, to variables whichreflect limitations of mobility (altitude), and to valley en-dogamy, which in turn depends on the census size deter-mining the disposability of potential mates within everyvillage.AcknowledgementsThanks are expressed to those who have made possi-ble data collection, especially to Justo García González(Avila Archbishopric Archive) and to Erik Lundin for re-vising the manuscript.R E F E R E N C E S1. CROW, J. F., A. P. MANGE, Eugen. Q., 12 (1965) 199. — 2. LAS-KER, G. W., Hum. Biol., 49 (1977) 489. — 3. PINTO-CISTERNAS, J., L.PINEDA, I. BARRAI, Am. J. Hum. Genet., 37 (1985) 373. — 4. FUSTER,V., Hum Biol., 58 (1986) 391. — 5. SHAW, R. F., J. Hered., 51 (1960) 221.— 6. LASKER, G. W., Anales de Antropología (Mexico), 28 (1991) 107. —7. FUSTER,V., A. M. JIMÉNEZ, S. COLANTONIO, Hum. Biol., 73 (2001)249. — 8. FUSTER V., M. S. MESA, J. MARTIN, F. ORTEGA, M. B. MO-RALES, Rev. Esp. Antrop. Biol., 16 (1995) 85. — 9. CROW, J. F., Hum.Biol., 52 (1980) 1. — 10. LASKER, G. W.: Surnames and genetic structure.(Cambridge University Press, Cambridge, 1985). — 11. RELETHFORD,J. H., C. E. JAQUISH. Am. J. Phys. Anthrop., 77 (1988) 243. — 12. BION-DI, G., P. RASPE, C. G. N. MASCIE-TAYLOR, J. Biosoc. Sci., 32 (2000)459. — 13. FUSTER, V., Coll. Antropol., 9 (1985) 155. — 14. JORDE, L.B., Population structure studies and genetic variability in humans. In:ROBERTS, D. F., G. F. DESTEFANO (Eds.): Genetic variation and itsmaintenance. (Cambridge University Press, Cambridge, 1986). — 15. DEBRAEKELEER, M., Coll. Antropol., 19 (1995) 289. — 16. RELETHFORD,J. H., Am. J. Phys. Anthrop., 69 (1986) 377. — 17. RELETHFORD, J. H.,Riv. di Antrop., 74 (1996) 15. — 18. FUSTER, V., S. COLANTONIO, Hum.Biol., 74 (2002) 301.V. FusterDepartment of Zoology and Physical Anthropology, University Complutense of Madrid, 28040-Madrid, Spaine-mail: vfuster@bio.ucm.esANALIZA IZONIMIJE POPULACIJSKE STRUKTURE U GREDOSU, [PANJOLSKAS A @ E T A KU razdoblju od 1875. – 1975. godine provedena je analiza izonimije temeljena na 41.696 brakova sklopljenih u tridoline iz Gredosa, [panjolska (Tormes, Alberche and Tietar). Ukupno sro|ivanje (Ft) bilo je najni`e u dolini Tietar(0,0103-0,0136, zatim u dolini Tormes (0,0125-0,0255) pa u dolini Alberche (0,0153-0,0200). U potonjoj je slu~ajno sro-V. Fuster and S. Colantonio: Isonymic Analysis in Gredos, Spain, Coll. Antropol. 30 (2006) 1: 199–203202TABLE 3NON-PARAMETRIC () CORRELATION COEFFICIENT AMONG RANDOM (Fr), NON-RANDOM (Fn) AND TOTAL COEFFICIENTS (Ft)OF INBREEDING BY ISONYMY; INBREEDING COEFFICIENT (), CENSUS AND THE ENDOGAMY RATES (ER)Fr Fn Ft  Census Valley ER Village ERFn 0.468Ft 0.743* 0.904*** coefficient –0.061 0.732* 0.504Census size –0.239 –0.696* –0.679* –0.579**Valley ER –0.182 0.618** 0.375 0.721* –0.600**Village ER 0.725* 0.711* 0.829*** 0.343 –0.386 0.143Altitude 0.214 0.675* 0.621** 0.654* –0.946*** 0.643** 0.346Inbreeding coefficient  calculated from ecclesiastical dispensations, up to third degree. Endogamy rates obtained considering valleyand village as the population units. *p<0.01, **p<0.05, ***p<0.001|ivanje (Fr) nadma{ivalo neslu~ajno (Fn). Izra~unati su korelacijski koeficijenti kako bi se potvrdila povezanost izme|usro|ivanja izra~unatog na temelju analize izonimije sa stupnjem endogamije na razini sela i doline, veli~inom populacijelokaliteta, nadmorskom visinom i sro|ivanjem. Fn pokazuje pozitivnu povezanost s prosje~nim stupnjem endogamijena razini sela i doline te s nadmorskom visinom, ali i negativnu povezanost sa veli~inom populacije. Nasuprot tome, Frpokazuje zna~ajnu povezanost sa stupnjem endogamije sela. Osim sa stupnjem endogamije sela, obje varijable pokazujuistu povezanost s varijablama kao {to su nadmorska visina te stupanj endogamije doline. Nadmorska visina odr`avaograni~enje mobilnosti, a stupanj endogamije doline indicira dostupnost potencijalnih partera, {to opet ovisi o veli~inipopulacije.V. Fuster and S. Colantonio: Isonymic Analysis in Gredos, Spain, Coll. Antropol. 30 (2006) 1: 199–203203

Isonymic Analysis of Population Structure in Gredos, Spain

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