Genetic variation and racial admixture in the Miskito of the southern Mosquito Shore, Nicaragua

Abstract

A survey of the electrophoretic variation at eleven loci red-blood cell enzymes. hemoglobins and serum proteins was performed on a sample of 59 Miskitos stemming from the southernmost part of the Mosquito shore of Nicaragua. Seven loci ALB α-, β-, γ-globins, LDHA. LDHB, and TPI were monomorphic; API. CP. HP"and TF were polymorphic representing a proportion of polymorphic loci (P) of 0.364 and an average heterozygosity (H) of 0.077. Both values are within a range covered by ten Chibchan tribes of Costa Rica and Panama evaluated for the same loci -(P) = 0.364-0.182; (H) = 0.104-0.052-. The data allowed an estimation of minimum ( ml = 0.0), mean (mm = 7.34) and maximum (ms = 21.9) percentages of racial admixture with blacks. For comparison, admixture was also calculated from the data -mainly blood groups- of a previous survey performed in 1960 by A. Matson and his group on a sample of a region near the border between Nicaragua and Honduras; results (ml = 6.05), (mm = 11.0) and (ms = 18.1). The values showed no statistical difference for the mean estimates, under the assumption that the non-Indian alleles are Poisson-distributed (P=0.42). The documentation of what is supposed to be the beginning of the racial admixture of the Miskito with blacks in 1641 permitted the calculation of the rate of admixture per generation -generation length: 27 years-; its maximum value lies between 1.68 and 1.91 percent. These results indicate that the Miskito gene pool has a preponderance of features eharacteristic of Amerindian populations.