Genetic marker variation in coastal populations of Chile

HOMO Vol. 53/2, pp. 170–177 © 2002 Urban & Fischer Verlag http://www.urbanfischer.de/journals/homo

HOMO

Genetic marker variation in coastal populations of Chile E. LLOP1, Z. HARB1, R. MORENO1, F. ROTHHAMMER2 1

Programa de Genética Humana – Instituto de Ciencias Biomédicas Facultad de Medicina – Universidad de Chile 2 Departamento de Argueologia y Museológia Facultad de Cienzia Soziales, Administrativasy Económicas, Universidad de Tampere

Summary Gene frequencies for nine genetic marker systems are presented for the following Chilean coastal populations: Paposo, Carelmapu, Laitec and Ukika. Historical and anthropological data suggest the presence of descendants of the Amerindian populations, specifically of Changos, Cuncos, Chonos and Yamanas in these populations. Results indicate that the studied groups maintain an important aboriginal genetic composition. According to Amerindian admixture estimates, the genetic isolation of coastal populations is lower than that of inland populations, suggesting that proximity to the sea facilitated gene flow. Genetic distances and dendrograms were obtained for these populations and another four Chilean Indian populations. Results agree with expectations, taking geographic isolation and non-aboriginal admixture into account.

Introduction The long Chilean coast, with its many oceanic and continental islands, has been the habitat of several human groups during more than 10.000 years of population history. European conquerors and travellers have described for at least five centuries a variety of Indian populations. In this instance we have decided to study four coastal groups: the Changos of Northern Chile, the Cuncos and Chonos of South-Central Chile and finally, the Yamana of Southern Chile’s Archipelago (LLOP et al 1995). The Changos occupied a narrow coastal area comprising Southern Perú and Northern Chile between the Ocoña and Aconcagua rivers when the Spaniards arrived. They lived in small bands fishing and collecting shellfish and maintaining trade relationships with the small agricultural community living in the valleys. They numbered around 6000 individuals during the 15th century AD. According to Larrain (Munizaga 1988) the Changos could be considered extinguished by 1880–1890: Some mixed individuals survived in small bays between the cities of Antofagasta and Copiapo, particularly in the bay of Paposo. The Cuncos belonged to the Araucanian Confederation and peopled, when the Spanish Conquerors arrived, the coast between the Valdivia river and the channel of Chacao. They numbered around 10 000 individuals and some still survive in the coastal village of Carelmapu close to the Chacao Channel. The Chonos peopled the islands and archipelagos east and south of the island of Chiloé as far as the peninsula of Taitao (Romero et al 1990). Some thought that 0018-442X/02/53/02–170/$ 15.00/0

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these groups once peopled the entire island of Chiloé, and travelled even as far north as the coastal areas of Osorno and Llanquihue and were pushed southwards by the Cuncos who are sometimes also called Huilliches or Veliches. The Chonos numbered around 3000 individuals and lived in primitive shelters made from bushes. They used canoes made from wood for fishing. According to Larrain their admixture with the Spanish from Chiloé contributed to their extinction as a biological and cultural entity (Munizaga 1988). The remainder of this group can be found on the islands of Cailin, Huara, Laitec and Apiao. The Yamana, are also culturally speaking, firelanders. They inhabited the area of the Beagle Channel (Rothhammer and Cruz-Coke 1983, Llop et al 1995). They had sporadic contact with the Selknam, a group who mainly hunted guanaco (Munizaga 1988). From some 4000 individuals only 40 survive presently in Ukika, close to Port Williams. Most Yamana Indians died as a consequence of contact with European invaders. Nine genetic marker systems were analyzed in the coastal populations of Paposo, Carelmapu, Laitec and Ukika, in order to genetically characterize these groups, and to establish their possible origin, as well as to assess the percentage of Indian genes still present in their gene pool. Results were compared with other Chilean populations (Llop 1996) by means of a genetic distance analysis. Figure 1 shows the geographic location of the populations included in the present study.

Materials and methods We studied 47 individual residents of Paposo (25º3′ S, 70º27′ O); 55 individuals from Carelmapu (41º45’ S, 73º44′ O); 48 individuals from Laitec Island (43º24′ S, 73º38′ O); and 25 Yaghan Indians from Ukika (55º36′ S, 70º48′ O) (Llop et al 1995). Ten milliliters of blood was obtained from volunteers by venipuncture. Five milliliters, treated with acid citrate dextrose (ACD), was used for determination of blood groups, erythrocyte enzymes, and plasma proteins, and 5ml of heparinized blood was employed for HLA typing. Antigenic specificities were determined for ABO, Rh, MNSs, Duffy (Fy), and Kidd (Jk). All determinations were carried out in tubes containing 2% red cell suspensions, using sera from Biotest Serum Institute GMBH (Dreieich, Germany) and Gamma Biological Inc. (Houston, Texas). The erythrocyte enzymes phosphoglucomutase 1 (E.C.2.7.5.1) (PGM1) and esterase D (E.C.3.1.1.1.) (EsD) and the plasma protein haptoglobin (Hp), were assessed by starch gel electrophoresis following the procedures of Spencer et al (1964), Hopkinson et al (1973), and Paulik (1957). HLA determinations for loci A, B, and C were performed in the field applying the microlymphocytotoxicity method of Terasaki and McClelland (1964). HLA antisera were obtained from Biotest Diagnostic (Dreieich, Germany) and One Lambda (Los Angeles, CA). The following specificities were included: A1, A2, A3, A10, A11, A23, A24, A28, A29, A30, A31, A32, B5, B7, B8, B13, B14, B15, B17, B18, B21, B22, B27, B35, B38, B39, B40, B41, B44, B48, Cw1, Cw2, Cw3, Cw4, Cw5, Cw6, and Cw7.

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Figure 1: Map of Chile showing the geographic location of eight Chilean populations included in the present study. 1, Aymara; 2, Atacameño; 3, Paposo; 4, Pehuenche; 5, Huilliche; 6, Carelmapu; 7, Laitec; 8, Ukika.

For blood groups, enzymes, and protein loci; maximum likelihood gene frequency estimators were obtained using the MAXLIK computer program of Reed and Schull (1968). Gene frequencies for the HLA system were calculated by p = 1 – √1-f, where f is the antigen frequency (Mattiuz et al 1970). Neil (1978) unbiased distances were used in the generation of UPGMA (unweighted pair-group method with arithmetic averaging) dendrograms (Sneath & Sokal 1973) employing the BIOSYS programs described in Swofford & Selander (1981).

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We estimated the percentage of Indian admixture (m), for each population according to Bernstein (1931), using the most informative alleles of the ABO, Rh, MN, and haptoglobin systems, and also, we estimated the mean of the m values – as a weighted average, according to Cavalli-Sforza & Bodmer (1971). Gene ( m) frequencies of the ancestral populations (Spaniards and Mapuche Indians) were obtained from Campillo (1976), Goedde et al (1985) and Etcheverry et al (1967).

Results Gene frequencies for the marker systems studied are shown in table 1. The high frequency of ABO*0 in all studied populations is noteworthy. For the Duffy and MNSs systems, results are similar in all studied groups. Allele FY*a and haplotypes MNS*Ms and MNS*Ns are consistently the most frequent. It is of value to mention that the haplotype Rh*cde exhibits the highest frequency in Paposo (0.287) and the lowest frequency in Laitec (0.074). JK*b is most frequent in Laitec (0.809) and presents in lowest frequency in Paposo. The erythrocyte enzymes PGM1 and EsD, and the serum protein Hp are similarly distributed, with PGM1*1 and EsD*1 exhibiting the highest frequencies. The most frequent HLA alleles were HLA*A2, HLA*A28 and HLA*B39 in all populations. HLA*A1 was highly present only in Paposo. Table 2 shows the percentage of Amerindian admixture (m) estimated on the basis of alleles ABO*0, Hp*1, MN*M and haplotype RH*cde in the four popula– for all four systems. Paposo and tions, as well as the weighted average value ( m) – = 0.6107 and Carelmapu exhibit the lowest values of Amerindian admixture ( m 0.6130 respectively). Nei’s genetic distances among the coastal populations studied in this project, as well as other Chilean Indian groups (Aymara, Atacameño, Pehuenche and Huilliche) revealed that the lowest distances were found between Laitec and Carelmapu, Laitec and Pehuenches, Laitec and Huilliches and Pehuenches and Huilliches. The highest distances were observed between the Aymara and Paposo and Aymara and Huilliche. A graphic representation of the distances is shown in figure 2.

Figure 2: Dendrogram obtained for eight Chilean populations considering 62 alleles in 9 genetic systems.

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Table 1: Gene frequencies in four Chilean coastal populations.

System

Allele or haplotype

Gene Frequencies ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Paposo Carelmapu Laitec Ukika

ABO

ABO*A ABO*B ABO*O

0.089 0.000 0.911

0.075 0.033 0.892

0.028 0.056 0.916

0.043 0.043 0.914

Fy

FY*a FY*b

0.564 0.436

0.614 0.386

0.673 0.327

0.750 0.250

Jk

JK*a JK*b

0.543 0.457

0.343 0.657

0.191 0.809

0.333 0.667

MNSs

MNS*MS MNS*Ms MNS*NS MNS*Ns

0.135 0.428 0.068 0.369

0.187 0.458 0.000 0.355

0.182 0.555 0.000 0.263

0.312 0.459 0.000 0.229

Rh

RH*DCE RH*DCe RH*DcE RH*Dce RH*dCE RH*dCe RH*dcE RH*dce

0.042 0.372 0.235 0.000 0.000 0.064 0.000 0.287

0.026 0.557 0.245 0.000 0.000 0.000 0.000 0.172

0.020 0.571 0.316 0.019 0.000 0.000 0.000 0.074

0.000 0.479 0.354 0.048 0.000 0.000 0.000 0.119

Hp

Hp*1 Hp*2

0.666 0.334

0.564 0.436

0.672 0.328

0.523 0.477

PGM1

PGM1*1 PGM1*2

0.755 0.245

0.708 0.292

0.735 0.265

0.646 0.354

EsD

EsD*1 EsD*2

0.947 0.053

0.854 0.146

0.971 0.029

0.917 0.083

HLA

HLA*A1 HLA*A2 HLA*A3 HLA*A10 HLA*A11 HLA*A23 HLA*A24 HLA*A28 HLA*A29 HLA*A30 HLA*A31 HLA*A32 Blank HLA*B5 HLA*B7

0.122 0.189 0.014 0.105 0.014 0.000 0.029 0.283 0.014 0.029 0.155 0.029 0.017 0.074 0.074

0.019 0.240 0.039 0.000 0.039 0.059 0.080 0.215 0.019 0.039 0.251 0.000 0.000 0.059 0.039

0.020 0.200 0.020 0.000 0.041 0.000 0.128 0.337 0.020 0.000 0.175 0.000 0.059 0.083 0.041

0.000 0.418 0.054 0.000 0.027 0.027 0.146 0.274 0.027 0.000 0.027 0.000 0.000 0.054 0.054

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Table 1: Continued.

System

Allele or haplotype

Gene Frequencies ––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Paposo Carelmapu Laitec Ukika

HLA

HLA*B8 HLA*B13 HLA*B14 HLA*B15 HLA*B17 HLA*B18 HLA*B21 HLA*B22 HLA*B27 HLA*B35 HLA*B38 HLA*B39 HLA*B40 HLA*B41 HLA*B44 HLA*B48 Blank HLA*CW1 HLA*CW2 HLA*CW3 HLA*CW4 HLA*CW5 HLA*CW6 HLA*CW7 Blank

0.000 0.014 0.090 0.172 0.000 0.122 0.000 0.000 0.000 0.155 0.014 0.155 0.029 0.014 0.029 0.029 0.029 0.138 0.029 0.122 0.105 0.000 0.014 0.074 0.518

0.000 0.000 0.000 0.080 0.080 0.000 0.000 0.019 0.019 0.123 0.000 0.293 0.039 0.000 0.080 0.000 0.169 0.080 0.000 0.123 0.101 0.000 0.000 0.168 0.528

0.020 0.000 0.151 0.062 0.000 0.000 0.000 0.000 0.000 0.151 0.000 0.307 0.020 0.000 0.041 0.000 0.124 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.000

0.000 0.000 0.054 0.142 0.000 0.000 0.111 0.000 0.000 0.000 0.000 0.027 0.312 0.000 0.054 0.000 0.192 0.054 0.027 0.351 0.142 0.027 0.000 0.082 0.317

– for four Chilean coastal Table 2: Amerindian admixture estimates (m) with weighted averages (m) populations. System

Allele or Haplotype

Paposo m

Carelmapu m

Laitec m

Ukika m

ABO Rh Hp MN – Weighted average (m)

ABO*0 RH*cde Hp*1 MN*M

0.7845 0.2511 0.7064 0.3231 0.6107

0.7289 0.5508 0.4398 0.9079 0.6130

0.8001 0.8066 0.7220 1.5534 0.8012

0.7938 0.6890 0.3924 1.7995 0.7100

Discussion The four populations studied in this paper, presumably descendants of Chango, Chono, Cunco and Yamana Indians, share the genetic characteristics of their ancestors, bands of fishermen who traveled along the coast using canoes made from seawolf skin or wood according to the geographic location.

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Gene frequencies for ABO, Fy, MNSs, Hp, PGM1 and EsD are similar in these populations. The Rh system exhibits a high frequency of RH*cde in Paposo (0.287). This value is very close to the frequency encountered in Spain (CavalliSforza & Bodmer 1971). Conversely, the low frequency in Laitec (0.074) indicates higher Amerindian ancestry. Also the JK*b frequency in Laitec (0.809) followed by 0.667 in Ukika and 0.657 in Carelmapu are in contrast with the lower frequency in Paposo (0.457), which is similar to the value found in Caucasoid populations. The same tendency is observed for the HLA*A1 allele which exhibits in Paposo a frequency almost as high as in Caucasoids (0.122). Concerning the percentage of Indian admixture, in concordance with the tendency observed for gene frequencies, the highest percentage of Amerindian genes are present in Laitec and Ukika, populations which have preserved a high degree of geographic isolation. Paposo and Carelmapu have received a high immigration of individuals from other locations because of the commercial activity developed there. The genetic distance analysis reveals that Paposo and Ukika are significantly different. This is an expected finding because they exhibit different degrees of admixture and furthermore are geographically distant. Carelmapu and Laitec are closest genetically, which can be explained by gene flow between Cuncos and Chonos due to their geographic proximity. Comparison with other Chilean Indian groups indicates that Carelmapu and Laitec are close to Pehuenches and Huilliches. This is not surprising if we consider that Cuncos and Chonos are linguistically close to the Indians of the Araucanian Confederation (Steward 1963). The Aymara and Atacameño cluster together. For a comprehensive study of the microevolution of the Aymará populations see Dittmar (1994). Perhaps the most interesting finding is that the last Yamana from Ukika are genetically related to the Indians from the Araucanian Confederation, represented in this study by the Pehuenche, Huilliche, Cunco and Chono. This finding gives support to the hypothesis that Chile was peopled progressively from north to south (Rothhammer et al 1986, Rothhammer 1987).

Acknowledgments We are grateful to the people and authorities who collaborated with this study, especially to the city councils of Paposo, Carelmapu, Laitec and Ukika. Finally, we wish to thank the Paposo, Carelmapu, Laitec and Ukika villagers, who helped us to learn more about their ancestors. Supported by Fondecyt Proyects 1950594 and 1010131.

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