Alu polymorphisms in the Waorani tribe from the Ecuadorian Amazon reflect the effects of isolation and genetic drift

HLA allelic diversity in the Waorani population of Ecuador: Its significance to their ancestry and migration

The Waorani, an isolated indigenous tribe in Ecuador, have long been characterized by limited genetic diversity, with few studies delving into their genetic background. Human Leukocyte Antigen (HLA) genes which are located in the human major histocompatibility complex (MHC) provides valuable insights into population evolution due to its highly polymorphic nature. However, little is known about the HLA diversity and ancestry of the Waorani population. In this study, we sequenced eight HLA genes using Next Generation Sequencing (NGS) from 134 Waorani individuals and obtained up to four-field HLA allele resolution. Cluster and phylogenetic analysis show that the Waorani are genetically distant from other Ecuador populations, but instead show genetic affinities with the Puyanawa and Terena tribes from Brazil, as well as the Mixe tribe from Mexico. The identification of alleles common within the Waorani population, previously linked to specific health conditions, notably paves the way for future association analyses. This extensive study, employing Next-Generation Sequencing (NGS) technology, significantly enriches the sparse and segmented understanding of HLA diversity in the South American region. Our findings enhance the global comprehension of human genetic diversity and underscore the value of studying indigenous populations. Such research is vital for deepening our insights into human migration patterns and evolutionary processes.

On the Trail of Spatial Patterns of Genetic Variation

The accurate determination of the spatial trends on the variability of a species’ gene pool is essential to elucidate the underlying demographic-evolutionary events, thus helping to unravel the microevolutionary history of the population under study. Herein we present a new software called GenoCline, mainly addressed to detect genetic clines from allele, haplotype, and genome-wide data. This program package allows identifying the geographic orientation of clinal genetic variation through a system of iterative rotation of a virtual coordinate axis. Besides, GenoCline can perform complementary analyses to explore the potential origin of the genetic clines observed, including spatial autocorrelation, isolation by distance, centroid method, multidimensional scaling and Sammon projection. Among the advantages of this software is the ease in data entry and potential interconnection with other programs. Genetic and geographic data can be entered in spreadsheet table formatting (.xls), whereas genome-wide data can be imported in Eigensoft format. Genetic frequencies can also be exported in a format compatible with other programs dealing with population genetic and evolutionary biology analyses. All illustrations of results are saved in.svg format so that there will be high quality and easily editable vectorial graphs available for the researcher. Being implemented in Java, GenoCline is highly portable, thus working in different operating systems.

Potential research ethics violations against an indigenous tribe in Ecuador: a mixed methods approach

Background

Biomedical and ethnographic studies among indigenous people are common practice in health and geographical research. Prior health research misconduct has been documented, particularly when obtaining genetic material. The objective of this study was to crossmatch previously published data with the perceptions of the Waorani peoples about the trading of their genetic material and other biological samples.

Methods

We conducted a mixed methods study design using a tailored 15-item questionnaire in 72 participants and in-depth interviews in 55 participants belonging to 20 Waorani communities about their experiences and perceptions of participating in biomedical research projects. Additionally, we conducted a systematic review of the literature in order to crossmatch the published results of studies stating the approval of an ethics committee and individual consent within their work.

Results

A total of 40 men (60%) and 32 women (40%), with a mean age of 57 ± 15 years agreed to be interviewed for inclusion. Five main categories around the violation of good clinical practices were identified, concerning the obtention of blood samples from a recently contacted Waorani native community within the Amazonian region of Ecuador. These themes are related to the lack of adequate communication between community members and researchers as well as the voluntariness to participate in health research. Additionally, over 40 years, a total of 38 manuscripts related to the use of biological samples in Waorani indigenous people were published. The majority of the studies (68%) did not state within their article obtaining research ethics board approval, and 71% did not report obtaining the informed consent of the participants prior to the execution of the project.

Conclusion

Clinical Research on the Waorani community in the Ecuadorian Amazon basin has been performed on several occasions. Unfortunately, the majority of these projects did not follow the appropriate ethical and professional standards in either reporting the results or fulfilling them. The results of our investigation suggest that biological material, including genetic material, has been used by researchers globally, with some omitting the minimum information required to guarantee transparency and good clinical practices. We highlight the importance of stating ethics within research to avoid breaches in research transparency.

Questioning the "melting pot": analysis of Alu inserts in three population samples from Uruguay

The way that immigrants integrate into recipient societies has been discussed for decades, mainly from the perspective of the social sciences. Uruguay, as other American countries, received diffferent waves of European immigrants, although the details of the process of assimilation, when it did occur, are unclear. In this study we used genetic markers to understand the process experienced by the Basques, one of the major migration waves that populated Uruguay, and their relation to other immigrants, as well as to Native American and African descendants. For this purpose, we analyzed the allele frequencies of 10 ALU loci (A25, ACE, APOA1, B65, D1, F13B, PV92, TPA25, HS2.43, and HS4.65) in three samples from Uruguay (two of Basque descendants, one of non-Basque descendants) from two locations: Montevideo and Trinidad. No departure from Hardy-Weinberg expectations was observed, with the exceptions of the APOA1 and D1 loci in the non-Basque descendants' samples. Our data show that the major genetic contribution in the three samples comes from Europe (78-88%), with minor African (10-15%) and Native American (0-10%) contributions. Genetic distances reveal that Basque descendants from Trinidad cluster with Europeans, whereas both Montevideo samples cluster together and are separate from other populations, showing two diffferent types of integration, related to the general characteristics of each regional population.

Young Alu insertions within the MHC class I region in native American populations: insights into the origin of the MHC-Alu repeats

OBJECTIVES

Genetic heterogeneity of two Amerindian populations (Jujuy province, Argentina, and Waorani tribe, Ecuador) was characterized by analyzing data on polymorphic Alu insertions within the human major histocompatibility complex (MHC) class I region (6p21.31), which are completely nonexistent in Native Americans. We further evaluated the haplotype distribution and genetic diversity among continental ancestry groups and their potential implications for the dating of the origin of MHC-Alus.

METHODS

Five MHC-Alu elements (AluMicB, AluTF, AluHJ, AluHG, and AluHF) were typed in samples from Jujuy (N = 108) and Waorani (N = 36). Allele and haplotype frequency data on worldwide populations were compiled to explore spatial structuring of the MHC-Alu diversity through AMOVA tests. We utilized the median-joining network approach to illustrate the continental distribution of the MHC-Alu haplotypes and their phylogenetic relationships.

RESULTS

Allele and haplotype distributions differed significantly between Jujuy and Waorani. The Waorani featured a low average heterozygosity attributable to strong population isolation. Overall, Alu markers showed great genetic heterogeneity both within and among populations. The haplotype distribution was distinctive of each continental ancestry group. Contrary to expectations, Africans showed the lowest MHC-Alu diversity.

CONCLUSIONS

Genetic drift mainly associated to population bottlenecks seems to be reflected in the low MHC-Alu diversity of the Amerindians, mainly in Waorani. Geographical structuring of the haplotype distribution supports the efficiency of the MHC-Alu loci as lineage (ancestry) markers. The markedly low Alu diversity of African populations relative to other continental clusters suggests that these MHC-Alus might have arisen after the anatomically modern humans expanded out of Africa.

Assessing the genetic influence of ancient sociopolitical structure: micro-differentiation patterns in the population of Asturias (Northern Spain)

The human populations of the Iberian Peninsula are the varied result of a complex mixture of cultures throughout history, and are separated by clear social, cultural, linguistic or geographic barriers. The stronger genetic differences between closely related populations occur in the northern third of Spain, a phenomenon commonly known as "micro-differentiation". It has been argued and discussed how this form of genetic structuring can be related to both the rugged landscape and the ancient societies of Northern Iberia, but this is difficult to test in most regions due to the intense human mobility of previous centuries. Nevertheless, the Spanish autonomous community of Asturias shows a complex history which hints of a certain isolation of its population. This, joined together with a difficult terrain full of deep valleys and steep mountains, makes it suitable for performing a study of genetic structure, based on mitochondrial DNA and Y-Chromosome markers. Our analyses do not only show that there are micro-differentiation patterns inside the Asturian territory, but that these patterns are strikingly similar between both uniparental markers. The inference of barriers to gene flow also indicates that Asturian populations from the coastal north and the mountainous south seem to be relatively isolated from the rest of the territory. These findings are discussed in light of historic and geographic data and, coupled with previous evidence, show that the origin of the current genetic patterning might indeed lie in Roman and Pre-Roman sociopolitical divisions.

Ancestry markers from the human chromosome 6: Alu repeats from the MHC in autochthonous Basques

Polymorphic Alu insertions from the MHC class I region were analyzed in 215 autochthonous Basques from Guipuzcoa and Navarre provinces, with the aim of contributing new MHC Alu data in European ancestry populations. We also seek to assess both the genetic position of native Basques among worldwide samples and the efficiency of the MHC Alu elements as ancestry informative markers (AIMs). According to the MDS and AMOVA results, worldwide populations included in the comparative analyses were grouped in three major clusters defined by genetic ancestry (Africans, Asians and Europeans). The δ values (differences in weighted allele frequencies) among ancestry groups indicated that Alu elements within the alpha-block (AluHF, AluHJ and AluHG) showed an adequate resolving power to discriminate appropriately between some of the major ancestry groups. Alpha block Alu were also revealing of the exceptionality of Basques, as they allowed for the detection of genetic heterogeneity even between Basques and the other Iberian collection considered in the analysis (Valencia). Thus, analysis of the Alu loci within the alpha-block may represent a reliable, informative and cost-effective method to explore the ancestry, geographic origins and demographic history of human populations, which can be very helpful for studies into epidemiological, forensic or evolutionary perspectives.

Genetic uniqueness of the Waorani tribe from the Ecuadorian Amazon

South America and especially the Amazon basin is known to be home to some of the most isolated human groups in the world. Here, we report on a study of mitochondrial DNA (mtDNA) in the Waorani from Ecuador, probably the most warlike human population known to date. Seeking to look in more depth at the characterization of the genetic diversity of this Native American tribe, molecular markers from the X and Y chromosomes were also analyzed. Only three different mtDNA haplotypes were detected among the Waorani sample. One of them, assigned to Native American haplogroup A2, accounted for more than 94% of the total diversity of the maternal gene pool. Our results for sex chromosome molecular markers failed to find close genetic kinship between individuals, further emphasizing the low genetic diversity of the mtDNA. Bearing in mind the results obtained for both the analysis of the mtDNA control region and complete mitochondrial genomes, we suggest the existence of a 'Waorani-specific' mtDNA lineage. According to current knowledge on the phylogeny of haplogroup A2, we propose that this lineage could be designated as subhaplogroup A2s. Its wide predominance among the Waorani people might have been conditioned by severe genetic drift episodes resulting from founding events, long-term isolation and a traditionally small population size most likely associated with the striking ethnography of this Amazonian community. In all, the Waorani constitute a fine example of how genetic imprint may mirror ethnopsychology and sociocultural features in human populations.