Spatial assessment of Argentinean genetic admixture with geographical information systems

Article Outline

• Abstract
• 1. Introduction
• 2. Materials and methods
  • 2.1. Samples
  • 2.2. Genotypes
  • 2.3. Study area
  • 2.4. Clustering procedure and frequency computation
  • 2.5. Geostatistical analysis
• 3. Results
  • 3.1. Haplotype clustering
  • 3.2. Summary maps
• 4. Discussion and conclusions
• Acknowledgments
• Appendix A. Supplementary data
• References
• Copyright

Abstract 

In recent years there has been much attention to Argentinean population stratification. We were interested in assessing population stratification from a geographical perspective and summarizing it in form of maps. We mapped the genetic admixture of the extant male population in central and northern Argentina on the basis of forensic Y-chromosomal haplotypes. We addressed the question which group of genetically similar individuals is predominant in this area. Haplotypes containing seven Y-chromosomal short tandem repeat polymorphisms (Y-STRs), also known as microsatellites – DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393 – were constructed for 145 individuals, recruited in 10 provinces. 97 distinct haplotypes were clustered into four clusters according to molecular distances. A genetic geostatistical analysis was conducted with the open-source geographical information system GRASS GIS. For each haplotype cluster, the according frequency was spatially interpolated over the total study area. Juxtaposing the interpolation surfaces, we screened point-wisely the maximal frequency as well as the label of the respective cluster. The screening results were combined in one summary map. We repeated this procedure for the second maximal frequencies. The resulting maps subdivide the study area into continuous regions comprising one predominant group of similar haplotypes. The first summary map divides the study area into three regions and the second summary map divides the area into four regions. The results of our analysis indicate that two groups of similar European haplotypes alternatively dominate the largest extension of the Argentinean territory. A third group, including South-American haplotypes, dominates the indigenous northwestern Argentinean area. The last group, including worldwide dispersed haplotypes, preponderates in frequency in second place in central Argentina. Our findings confirm a widespread European paternal ancestry, a substantial Amerindian contribution in the northwest, as well as a considerable proportion of diverse paternal lineages. In this work, we further discuss these findings in reference to ethno-historical, genetic, and demographic information.

Keywords: Genetic admixture, Geographical information system, Forensic Y-STR haplotypes

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1. Introduction 

Contemporary Argentinean population is highly admixed (e.g. [1], [2], [3]). Since the first European arrivals in the 16th century, immigration from all over the world populated this territory. During the first three centuries, admixture took place mainly among few sedentary native groups, a low number of Spaniards coming to this viceroyalty, as well as a reduced number of Africans. The colonial society extended over relatively circumscribed regions of the future Argentinean territory. The largest extension of the modern Argentinean territory remained unexplored and most nomadic natives eluded conquerors for generations, even centuries. At the end of the 19th century, not integrated aborigines were either exterminated or reduced to isolated geographical spots. Deciding major immigration processes started in the 1850s and continued up to the present. Immigrants arrived usually in groups. Although a great majority was of Western European origin, a not negligible portion came from Eastern Europe, Asia, and Africa. Moreover, Western European immigration did not constitute a quite homogeneous population. This long-lasting, strongly officially promoted immigration tremendously outnumbered the scarce and geographically circumscribed colonial population (mainly Spaniards, creoles – individuals of admixed Spanish and Indigenous ancestry – as well as the extreme few left aboriginal groups, and other minor ethnicities). Previous to these major immigration waves, neither the native population size, the number of arriving Spaniards, nor the group size of other minor ethnicities arriving to the colonies was comparable with the large population sizes of other American territories (reviewed in [4], [5], [6], [7]). Nowadays, self-identifying Amerindian groups or individuals contribute only to an exiguous portion of the total population, restricted to scanty, marginal areas [5], [8], [9]. Consequently, the relatively recent immigration rapidly growing since the 1850s must have markedly diluted the colonial admixture and played a major role in modulating the extant Argentinean genetic background. Almost two hundred years of strong admixture among worldwide incoming lineages results in a complex spatial pattern of genetic variation.

Forensic Y-chromosome short tandem repeats (Y-STRs), also known as microsatellites, are extremely polymorphic markers. Since non-recombinant Y-chromosomal loci are jointly inherited, these may be combined into unambiguous haplotypes and they therefore offer an even more polymorphic data set. Several previous works confirmed the suitability of forensic Y-STR haplotypes for genetic studies of closely related populations (e.g. [10], [11]). Grouping haplotypes according to genetic similarity and assessing their geographical distribution is best suited for elucidating spatial patterns of genetic variation (e.g. [12]).

The aim of this work was to analyze and summarize the genetic substructure of the extant male Argentinean population geographically. Our work rests on the following three assumptions: (a) non-recombinant Y-STRs differentiate according to the stepwise-mutation model, (b) genetic variation within populations is spatially dependent, and (c) geographical distribution of groups of genetically similar individuals may overlap within a region. The first assumption, namely the commonly admitted model for the generation of diversity between non-recombinant Y-chromosomal STRs, allows us to cluster Y-STR haplotypes according to molecular distances. The second assumption is based on the idea that humans do not populate an area randomly, but genetically related individuals may tend to reside in geographically adjacent areas. Continuous geographical dependence is the condition to perform spatial interpolation, which is the main instrument of this work. The third assumption implies that geographical distribution of one group should be explored independently from other groups. As a main result of our work, we mapped the geographical distribution of most predominant groups of genetically closer males according to non-recombinant Y-chromosomal data. This is the first work reporting on summary maps of Argentina's genetic admixture.

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2. Materials and methods 

2.1. Samples 

DNA samples were obtained from 145 unrelated male Argentinean citizens. Samples were selected and indexed according to the province (federal state) of residence (see Table 1). Donors were recruited in the framework of legal paternity testing. In each case, paternity testing was either privately or publicly financed, depending on the socio-economic situation of the donor. Care was taken that neither closely related males nor non-Argentinean citizens were included in the study. Since this type of sampling makes no distinction among socio-economic or ethnic groups, and due to the fact that no further restrictions were introduced, this data set is a random sample of the extant male Argentinean population in the study area. Samples and genotypes were treated anonymously, following local ethical restrictions.

Table 1. Description of spatial units: “location” indicates the capital city selected as geographical reference for interpolation surface (see Section 2); “ID” refers to the province identification used in Fig. 1; “sample” refers to sample count per province; “total” refers to sample count per spatial unit.

DNA was extracted from blood stains or buccal swab specimens by conventional organic extraction methods.

2.2. Genotypes 

DNA was prepared and genotyped at the DNA Analysis Unit, Official College of Pharmacists and Biochemists, Buenos Aires, using the commercial typing kit PowerPlex Y System (Promega Corp.) – DYS19, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 – in a 25μl reaction volume, as specified by the manufacturer (Promega, Madison, WI, www.promega.com). Detection of the amplified fragments was done using the ABI Prism 377 (Applied Biosystems, Foster City, CA). PowerTyper Y Macro (Promega) was used to assign the alleles.

Alleles are designed in terms of the number of variable repeats, in accordance with the free-accessible worldwide YHRD database (http://www.yhrd.org). DYS385 was excluded from the analysis since it is not possible to assign alleles to a specific locus (e.g. [12]). DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393 were combined in accordance to the YHRD 7-STR data set and presented in the same order as in YHRD. Haplotypes are denoted in further sections listing the seven alleles concatenated by a dash (i.e. DYS19_389I_389II_390_391_392_393).

Once shared haplotypes were identified, we inspected worldwide probable provenance of the most frequent haplotypes in the sample. According to historical, ethnological, and census data [5], [6], [8], [9] it is to assume that the contemporary Argentinean population is to the greatest extent the result of modern admixture arisen from major immigration processes, officially promoted since the 1850s. This new long-lasting immigration, arriving from all over the world, in great measure outnumbered the colonial population, most probably diluting previous admixture among a reduced group of sedentary Amerindian populations, Spaniards, and some other minor ethnicities [4], [5], [6], [7], [8]. Since Y-STR haplotypes are paternally inherited as a block, without recombination, we assumed that the worldwide distribution of a haplotype would provide a good guess about the region where that haplotype came from before it integrated into the Argentinean population. In order to infer the most probable origin of a haplotype, worldwide geographical distribution was searched in the YHRD database (http://www.yhrd.org).

2.3. Study area 

The study area covers central and northern Argentina. It includes 10 sampled provinces and 10 further provinces within the area circumscribed by the sampled provinces (Fig. 1). These 20 provinces (out of a total of 24 Argentinean provinces) represent 80 percent of the total Argentinean extension. From a demographic point of view, it is worth noting that since Argentina is an extremely centralized and highly urbanized country, our sampled area contains the absolute majority of the total population. While our 10 sampled provinces include 75 percent of the total population, the study area includes 80 percent [13].

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• Fig. 1. 

  The study area is delineated wit thicker contour; 20 of the total 24 Argentinean provinces are included: A: Jujuy; B: Salta; C: Formosa; D: Chaco; E: Santiago del Estero; F: Tucuman; G: Catamarca; H: La Rioja; I: San Juan; J: Cordoba; K: Santa Fe; L: Misiones; M: Corrientes; N: Entre Rios; O: Buenos Aires; P: La Pampa; Q: San Luis; R: Mendoza; S: Rio Negro; T: Neuquen; spatial units with recruitment data (count=6) are indicated with black contour. References about recruitment (1–6c) are given in Table 1; diamond symbol indicates a capitals city used as geographical reference of genotype frequencies.

For the purpose of spatial interpolation, we grouped sampled provinces into 6 spatial units (Fig. 1). Frequency values were geographically referenced to capital cities. In the case of spatial units containing more than one, we selected the capital city of the province with the highest number of samples within the unit (Table 1).

2.4. Clustering procedure and frequency computation 

We clustered the 97 distinct haplotypes, taking into account molecular distances, into four clusters. The clustering procedure was performed with SAS software package (SAS for Windows, version 9.1; SAS Institute Inc., Cary, NC, USA; http://www.sas.com; clustering method: ward; Euclidean distance). For each spatial unit and cluster, absolute and relative frequencies were calculated. Relative frequencies were standardized in relation to the total count of samples. Global frequencies (q) were then stabilized: [14]

2.5. Geostatistical analysis 

Cluster frequencies were spatially interpolated with the open-source geographical information system GRASS GIS 6.4 (Geographic Resources Analysis Support System, http://grass.itc.it). For our analysis we chose the interpolation function “regularized spline with tension”, implemented in the package v.surf.rst [15]. This method computes the values of the interpolation surface using a function which simulates a thin flexible plate passing through or close to the points [15]. All further geographical analysis was performed with GRASS GIS. We obtained four interpolated surfaces, each showing the estimated cluster frequency over the total study area. In other words, we estimated the probability of finding an individual belonging to one cluster, conditioned to the sampling point. Juxtaposing all four interpolated surfaces, we screened for each geographical point of the study area the highest frequency value and the respective cluster label. We repeated this step for the second highest frequency. Combining information about frequency and cluster label in one map, we spatially summarized the geographical distribution of the most (maximum summary map), as well as the second most (2nd maximum summary map) predominant haplotype clusters.

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3. Results 

3.1. Haplotype clustering 

Out of 145 samples, 97 distinct haplotypes were identified. 72 haplotypes were detected only once in the data set, and 18 haplotypes, twice. 7 haplotypes with an absolute frequency larger than two added 25 percent of the total sample (Table 2). Of these, only one haplotype (13_14_31_23_10_16_14; count: 5) is most frequently registered in South America, considering its worldwide geographical distribution. The most frequent haplotype (14_13_29_24_10_13_13; count: 9) is predominantly found in Western Europe.

Table 2. List of the most frequent haplotypes in the sample (absolute frequency>2).

The clustering process sorted distinct haplotypes into four relatively similar groups in respect to both total count of distinct haplotypes and count of samples per cluster (Table 3).

Table 3. Number of distinct haplotypes per cluster, percent of distinct haplotypes per cluster, absolute count of samples per cluster and percent of the total sample assigned to each cluster.

Frequent haplotypes of cluster 1 and of cluster 3 are throughout the world most frequently registered in Western Europe and with considerable frequency in North and South America. Cluster 3 included one frequent haplotype (14_13_30_23_10_11_12; n=3) showing as well high frequencies in the Middle East and in Southern Asia. The most frequent haplotypes included in cluster 2 are registered with higher frequency in Latin America and in North Africa. Cluster-4 haplotypes (n≥2) are scarcely distributed throughout the world; they are registered either in South America, Africa or Southeastern Asia (Table 1, electronic supplement).

3.2. Summary maps 

The spatial screening of haplotype clusters with the highest frequencies (maximum summary map) divided the study area into three regions (Fig. 2a). Cluster 1 (blue) covered the largest portion of the study area, about 90 percent (Table 4). However, the area covered by cluster 1 presented lower maximal global frequencies than the two other regions. The highest frequencies of cluster 1 were measured in Santa Fe and neighboring provinces. Lower frequencies were registered towards northern and western Argentina. Cluster 2 (green) was circumscribed to the two northwestern Argentinean provinces, Jujuy and Salta, which contribute about 11 percent of the study area. Higher frequencies were measured in Jujuy. This cluster accounted for the highest global frequencies. Cluster 3 (yellow) was reduced to only half of a spatial unit, over the Misiones Province, adding only 1 percent of the study area. Its maximal frequencies were observed at the border with Brazil.

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• Fig. 2. 

  Summary maps of the geographical distribution of predominant haplotype clusters, lighter and darker shading indicates higher and lower global cluster frequency, respectively; (a) clusters accounting for the maximal frequencies; (b) clusters accounting for the second maximal frequencies.

Table 4. Total area (given in percent of the total study area) covered by each haplotype cluster in the maximum and 2nd maximum summary maps.

The results of the screening for the haplotype clusters with the second highest frequency (2nd maximum summary map) are presented in Fig. 2b. In this map all four haplotype clusters were included. Cluster 1 (blue) was circumscribed to the extreme northeast, in the Misiones Province, and to the northwest of Argentina, in Jujuy and Salta Provinces, spanning over 12 percent of the total study area (Table 4). Cluster 2 (green) distributed as a stripe around cluster 1, with higher frequencies along the border of cluster 1 and covering a surface similar to it. Cluster 3 (yellow) distributed along all the periphery of central Argentina. It extended over one third of the total study area. Higher values were observed in the Andean region. Cluster 4 (red) covered the complete central region of the study area, about half of the total surface. Similar maximal global frequencies were measured for all four clusters.

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4. Discussion and conclusions 

The aim of this study was to summarize paternal lineage stratification in central and northern Argentina [2], [3] in form of quantitative maps obtained thanks to genetic geostatistical analysis of forensic Y-STR haplotypes. First, haplotypes were clustered according to the stepwise-mutation model. Second, spatial extension and frequency distribution of the most predominant haplotype clusters were quantified. Our study area, approximately 80 percent of the country's territory (20 provinces out of 24 provinces), comprises the area surrounded by the 10 sampled provinces. Since the sampled provinces contain the largest portion of the total Argentinean population (75 percent), and the study area, which contains 80 percent of the total population [13], is the oldest and largest region of modern Argentina, it must be noted that our results may be extrapolated to the general male population.

According to our results, the largest portion of the Argentinean territory is primarily populated by two groups of closely related haplotypes (cluster 1, indicated with blue in Fig. 2, and cluster 3, indicated with yellow). Both groups are likely of European origin. The most abundant haplotypes within these two clusters are more frequently registered in Europe and in North and South America. These findings coincide with the expected predominant European origin of paternal lineages [2], [3]. The overwhelmingly large immigration waves populating Argentina since the 1850s introduced a strong European component, diluting previous admixture (e.g. [16]). Cluster 3 included one frequent haplotype (14_13_30_23_10_11_12), which is worldwide found in the Middle East as well as in Southern Asia. Further analysis is required to precisely depict differential provenance of haplotypes included in these two groups.

Cluster 1 (indicated with blue in Fig. 2) included the geographically most widespread haplotypes in Argentina. This cluster showed either the highest or the second highest frequency over the whole study area (Fig. 2). This result is consistent with previous genetic studies indicating a predominance of European ancestry of the Y-chromosomal haplotypes in our study area (e.g. [2], [3]). Higher frequencies of this cluster, with presumable European origin, were measured in the Santa Fe Province and surroundings. This pattern is congruent with the course of migration. Santa Fe, as one of the oldest and largest centers, was an important focus of European immigration [6]. Culture as well as primary production in urban and rural areas clearly denotes the strong and long-lasting European influence in this province. Nevertheless, our results indicate that the territory with the highest predominance of cluster 1 (maximum summary map) is very admixed. Cluster 1 presented lower maximal global frequencies (q) than cluster 2 (green) and 3 (yellow). Its relatively lower global frequency points out that other groups are also present in the area in considerably high number. This is in accordance with Argentina's demographic development. In addition to a decisive European contribution – principally led back to the strong immigration waves since the 1850s – new immigration flow since the middle of the 20th century reintroduced a strong component of Amerindian and African population from neighboring countries [16], as well as other paternal lineages arriving from remoter countries [6], and modulated a multi-ethnic admixture in central Argentina [1], [2], [3], [16], [17].

Cluster 3 (indicated with yellow in Fig. 2), the second group of assumed European origin, overcame other clusters in frequency only in the Misiones Province, located near the northeastern border to Brazil and Paraguay. Misiones is today a region characterized by forestry and small farming [13], the latter already established in the 1930s by energetic and highly successful official programs to attract substantial new European immigration [6]. Amerindian groups inhabiting this province are extremely small. They presumably arrived to this territory after the local indigenous groups got extinguished, and subsist relatively isolated from western population [8]. In comparison to metropolitan industrial areas, Misiones smallholding system encourages less neighboring migration, which could have reintroduced substantial Amerindian component to the population. This province remained relatively isolated from farther regions. It is located about 715 miles far away from the Argentinean capital city, Buenos Aires, the most influencing metropolis of this extremely centralized country. All in all, these circumstances confirm our findings in the northeast, indicating a predominance of European paternal lineage in the region (e.g. [2], [3]), less admixed than central Argentina and with slightly differentiated genetic background.

Cluster 2 (indicated with green in Fig. 2) showed the highest frequency in northwestern Argentina, in Jujuy and Salta provinces, with higher frequencies in the first province. Cluster 2 retained the second highest frequency in the area including the provinces of La Rioja, Tucuman, northern Chaco and Formosa, which surrounds the region with the highest frequencies for this cluster. The region covered by cluster 2, both as maximum or as second maximum, must be considered less admixed than other regions, since its global frequencies tended to be higher than the rest. The prevalent haplotypes of cluster 2 are most frequently registered in Latin America, indicating a presumably Amerindian origin. Census data indicate that Jujuy Province nowadays counts Argentina's highest percentage of population (10%) identifying him- or herself as an indigenous person or descendant [9]. One of the last Argentinean Amerindian populations, survivor of the European colonization, the Kollas, resides mainly in the Jujuy Province, and extends with lower frequencies to the south [9]. This ethnic group still maintains several aspects of the time when it was the most advanced culture in the pre-Columbian Argentinean territory. Cultural and physiognomic aspects clearly differentiate them from European immigrants. The Kollas’ spatial distribution coincides with the geographical patterns assigned to cluster 2 in the maximum and 2nd maximum summary maps. Copious studies investigated Amerindian contribution to the genetic structure of Argentina (e.g. [1], [2], [3], [16]). Argentinean population keeps a higher percentage of Amerindian maternal heritage (e.g. [3]), whereas the paternal Amerindian component is present in the whole population as well, but to a much lower degree (e.g. [2], [3]). Specifically concerning the northwest of Argentina, several studies support a major contribution of Amerindian component [1], [2], [17]. Our findings further reinforce a predominant indigenous paternal heritage in northwestern Argentina, much less diluted by colonial and modern immigration than in other regions [1], [2], [3], [17]. The measured spatial frequencies indicating cluster 2 either as first or as second maxima in the northwest are in good agreement with our expectations.

The map showing the geographical distribution of clusters with the second highest frequency (2nd maximum summary map) included a further group, cluster 4 (indicated with red in Fig. 2). No clear continental origin could be assigned to the most frequent haplotypes included in this cluster. Haplotypes are dispersed over all continents with low frequencies. This is consistent with the continued Argentinean immigration policy. A mixed paternal lineage coming from all over the world (cluster 4), widespread across central Argentina – a region embracing the largest proportion of Argentinean population – confirms previous hypothesis of a multi-ethnic genetic composition of the extant population (e.g. [1], [2], [3], [16], [17]), led back to major immigration waves since the middle of the 19th century up to these days [5], [6].

Plenty and consequent published results demonstrated genetic stratification among Argentinean regions (e.g. [1], [2], [3], [16], [17]). In this paper, we analyzed stratification of male lineages dominating nowadays the Argentinean genetic landscapes from a geographical perspective. We combined statistical genetics and geostatistical analysis to exploit the high levels of resolution of forensic Y-STR haplotypes, especially suitable for detecting small genetic differences, arranged according to the YHRD 7-STR haplotype (www.yhrd.org). We produced summary frequency maps of the most predominant clusters of Y-STR haplotypes, and we compared relative differences of frequencies among haplotype groups in order to estimate the relative degree of admixture in a tract of land. These two summary maps showed the geographical distribution and frequency of most predominant groups of genetically similar individuals of the extant male Argentinean population according to Y-linked STR loci. This work adds a new, precise basis for further human population studies of this multi-ethnic country.

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Acknowledgments 

The authors wish to thank Dr. Lodovica Borghese and Diana Müller for helpful comments and criticisms. We are greatly thankful to Dr. Horacio R. Diaz for his support by reviewing Argentinean history and demographic development. We are also grateful to the anonymous reviewers for their constructive comments. We specially thank Daniela Holler for her kind support.

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Appendix A. Supplementary data 

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References 

1. Alfaro EL, Dipierri JE, Gutiérrez NI, Vullo CM. Genetic structure and admixture in urban populations of the Argentine North-West. Ann. Hum. Biol. 2005;32(6):724–737
   • View In Article
   • MEDLINE
   • CrossRef
2. Marino M, Sala A, Corach D. Genetic attributes of the YHRD minimal haplotype in 10 provinces of Argentina. Forensic Sci. Int. Genet. 2007;1(2):129–133
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (228 KB)
   • CrossRef
3. Corach D, Lao O, Bobillo C, van Der Gaag K, Zuniga S, Vermeulen M, et al. Inferring continental ancestry of Argentineans from autosomal, Y-chromosomal and mitochondrial DNA. Ann. Hum Genet. 2010;74(1):65–76
   • View In Article
   • CrossRef
4. Levene R. Las Indias No Eran Colonias. Buenos Aires: Espasa Calpe; 1951;
   • View In Article
5. N. Sanchez-Albornoz, La Población De América Latina, Desde Los Tiempos Precolombinos Al Año 2025, 2. ed., Editorial Alianza, Madrid, 1994.
   • View In Article
6. Rock D. Argentina, 1516–1987: from Spanish colonization to Alfonsín. Los Angeles: University of California Press; 1987;
   • View In Article
7. Levene R. 25th ed.. Lecciones de historia argentina. vol. I. Buenos Aires: Ediciones Corregidor; 1992;
   • View In Article
8. Bartolome MB. Argentinien. In:  Walter D editors. Die Situation der Indios in Südamerika. Grundlagen der interethnischen Konflikte der nichtandinen Indianer. Wuppertal: Hammer Verlag; 1976;p. 352–398
   • View In Article
9. INDEC, Encuesta Complementaria de Pueblos Indígenas (ECPI) 2004–2005 – Complementaria del Censo Nacional de Población, Hogares y Viviendas 2001. Instituto Nacional de Estadistica y Censo, Buenos Aires, 2005.
   • View In Article
10. Roewer L, Kayser M, Dieltjes P, Nagy M, Bakker E, Krawczak M, et al. Analysis of molecular variance (AMOVA) of Y-chromosome-specific microsatellites in two closely related human populations. Hum. Mol. Genet. 1996;5(7):1029–1033
    • View In Article
    • MEDLINE
    • CrossRef
11. Pérez-Lezaun A, Calafell F, Seielstad M, Mateu E, Comas D, Bosch E, et al. Population genetics of Y-chromosome short tandem repeats in humans. J. Mol. Evol. 1997;45(3):265–270
    • View In Article
    • MEDLINE
    • CrossRef
12. Gusmao L, Sanchez-Diz P, Alves C, Beleza S, Lopes A, Carracedo A, et al. Grouping of Y-STR haplotypes discloses European geographical clines. Forensic Sci. Int. 2003;134:172–179
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (223 KB)
    • CrossRef
13. INDEC, Censo 2001 . National Institute of Statistics and Censuses. www.indec.mecon.ar.
    • View In Article
14. Barbujani OG. A two-step test for the heterogeneity of FST values at different loci. Hum. Hered. 1985;35(5):292–295
    • View In Article
    • MEDLINE
    • CrossRef
15. Mitasova H, Mitas L. Interpolation by regularized spline with tension. I. Theory and implementation. Math. Geol. 1993;25:641–655
    • View In Article
16. Avena S, Goycoechea A, Dugoujon J, Slepoy M, Slepoy A, Carnese FR. Análisis Antropogenético de los Aportes Indígena y Africano en Muestras Hospitalarias de la Ciudad de Buenos Aires. Rev. Argent. Antropol. Biol. 2001;3(1):79–99
    • View In Article
17. Marino M, Sala A, Bobillo C, Corach D. Inferring genetic sub-structure in the population of Argentina using fifteen microsatellite loci. Forensic Sci. Int. Genet. Suppl. Series. 2008;1(1):350–352
    • View In Article