title: Alu polymorphisms in the Waorani tribe from the Ecuadorian Amazon reflect the effects of isolation and genetic drift.
abstract: OBJECTIVE
  The Amazon basin is inhabited by some of the most isolated human groups worldwide. Among them, the Waorani tribe is one of the most interesting Native American populations from the anthropological perspective. This study reports a genetic characterization of the Waorani based on autosomal genetic loci.
  
  
  METHODS
  We analyzed 12 polymorphic Alu insertions in 36 Waorani individuals from different communal longhouses settled in the Yasuní National Park.
  
  
  RESULTS
  The most notable finding was the strikingly reduced genetic diversity detected in the Waorani, corroborated by the existence of four monomorphic loci (ACE, APO, FXIIIB, and HS4.65), and of other four Alu markers that were very close to the fixation for the presence (PV92 and D1) or the absence (A25 and HS4.32) of the insertion. Furthermore, results of the centroid analysis supported the notion of the Waorani being one of the Amerindian groups less impacted by gene flow processes.
  
  
  CONCLUSIONS
  The prolonged isolation of the Waorani community, in conjunction with a historically low effective population size and high inbreeding levels, have resulted in the drastic reduction of their genetic diversity, because of the effects of severe genetic drift. Recurrent population bottlenecks most likely determined by certain deep-rooted sociocultural practices of the Waorani (characterized by violence, internal quarrels, and revenge killings until recent times) are likely responsible for this pattern of diversity. The findings of this study illustrate how sociocultural factors can shape the gene pool of human populations.
authors.affiliation: Departamento de Genética y Antropología Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Gómez-Pérez
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Alfonso-Sánchez
authors.forename: Dora
authors.initials: D
authors.lastname: Sánchez
authors.forename: Susana
authors.initials: S
authors.lastname: García-Obregón
authors.forename: Ibone
authors.initials: I
authors.lastname: Espinosa
authors.forename: Begoña
authors.initials: B
authors.lastname: Martínez-Jarreta
authors.forename: Marian M
authors.initials: MM
authors.lastname: De Pancorbo
authors.forename: José A
authors.initials: JA
authors.lastname: Peña
mesh_terms: D020087:Alu Elements; D004484:Ecuador; D005260:Female; D051456:Gene Flow; D005787:Gene Frequency; D040961:Genetic Drift; D006801:Humans; D007199:Indians, South American / Q000235:genetics*; D008297:Male; D011110:Polymorphism, Genetic