Population History and Mitochondrial Genetic Substructure of the Rama Amerindians from Nicaragua

Abstract

The Rama are a coastal population from southern Nicaragua who in large part were able to resist, at least for a time, the cultural changes and social reorganization brought on by colonial and modern influences. Historical information leaves the Rama origins and biological relationships with nearby extinct and extant groups ambiguous. The objective of this study was to examine the internal genetic microdifferentiation based on the first hypervariable region of the mitochondrial DNA (mtDNA) from a sample of approximately 20% of the population, and to expand the few available historical and anthropological data on the Rama by exploring the effects of cultural practices and historical events on genetic structure, providing an integrative perspective on the Rama genetic history. When considering differences in the spatial distribution and genetic diversity of the mtDNA haplotypes together with historical information on the Rama, a noteworthy pattern emerges. (a) Haplotypes are differentially distributed among a central Rama community (Punta Águila) compared with the other five peripheral communities (analysis of molecular variance: F CT = 0.10, p < 0.001), and their distribution is consistent with the historical relocation of this population after their split from Punta Gorda in the 18th century. (b) Differential genetic signatures found among central and peripheral Rama communities resemble two population histories: one of stability (haplogroup A2) and other of expansion (haplogroup B2), supporting the possibility that these patterns of genetic microdifferentiation between central and peripheral populations resulted from the 18th-century unification in southern Nicaragua of the Rama and a group of Voto migrants from Costa Rica that later split off and moved to the Bay of Bluefields.

Effect of Recent Historical Events on Migration and Isonymic Stratification among the Rama Amerindians from Nicaragua

“…As an independent test of the genetic differentiation between central and peripheral populations, Baldi (2013) performed analysis of molecular variance (AMOVA) (Excofffier et al 1992) and the Monmonier algorithm (Monmonier 1973) on mtDNA hypervariable region HVS-I sequences to detect barriers of gene flow and genetic segregation. According to AMOVA results, 9.5% of variation is explained among peripheral and central groups (FCT = 0.09, p < 0.001), and 87.2% of the total genetic variation is explained within Rama communities (FST = 0.13, p < 0.001).…”

“…Recent demographic surveys indicate that fewer than 1,500 Rama remain (Gobierno Territorial Rama y Kriol [GTR-K] 2007), and no more than 50 individuals are fluent in Rama as a consequence of a linguistic shift to Creole English (Craig et al 1986;Grinevald 2003). Phylogenetically, this population shares mitochondrial DNA (mtDNA) ancestry with other Chibchan-speaking communities from Colombia, Panama, and Costa Rica, demonstrating a high Amerindian component along their maternal line compared with the degree of European admixture (50%) present in their paternal ancestry (Baldi 2013;Melton et al 2013).…”

“…All participants in this study gave written informed consent to participate, and approval for study was granted by the institutional review board at the University of Kansas (approval 16735) and by the elders of the Rama community in Nicaragua. Genetic data, including mtDNA and NRY data, from this population have previously been reported (Baldi 2013;Melton et al 2013;Melton 2008). According to historical records, Rama Amerindians inherited their current surnames from British buccaneers and Creole merchants who resided on the Caribbean coast during the eighteenth century, while the Moravian missionaries established the rules of surname transmission in an efffort to ensure monogamous relationships among native communities (Moravian Mission of Rama Cay 1858-2013).…”

“…Researchers believe that the Rama originated when multiple indigenous populations admixed (Conzemius 1938;Riverstone 2004;Romero 1995); however, it has recently been proposed that a fraction of the Rama population is a remnant of the extinct Voto, a group that inhabited the same area until the seventeenth century. Displaced by European colonization and the Anglo-Spanish war (1761-1763) and held in the San Juan River region between Costa Rica and Nicaragua, a group of Voto relocated to the Punta Gorda River, which was inhabited by an earlier Rama group (Baldi 2013).…”

“…and N.F.B.) recently documented domestic networks connecting communities to their home base across many kilometers (Baldi 2013). Given that these communities are relatively recent phenomena that have not previously been investigated, this study sought to ascertain the degree of relatedness between and within subdivisions of seven Rama communities based on geographical patterns of surname variation and genealogical data.…”