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Genetic variation in wild Anopheles arabiensis Patton of Mwea Irrigation Scheme, Kenya

Published online by Cambridge University Press:  19 September 2011

Titus K. Mukiama
Affiliation:
Department of Botany, University of Nairobi P.O. Box 30197, Nairobi, Kenya
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Abstract

Electrophoretic variation was determined at eight enzyme loci in Anopheles arabiensis from four villages in Mwea Irrigation Scheme, Kenya. Seven loci had polymorphic alíeles of which at least two were common. Pooled allele frequencies at the Pgm, β-Had and Odh loci were in Hardy-Weinberg equilibrium, while those at the Ao, Idh, Adh, Est-1 and 6-Pgd loci showed significant deviations. The frequency of heterozygotes at the Adh, Est-1 and 6-Pgd loci was less than expected, while at the Ao locus, there was an excess. A 2 × 4 contingency χ2-test for each of the loci not in Hardy-Weinberg equilibrium indicated an association between the respective gene frequencies and the villages. The suggested explanation for these observations is that each village constitutes a distinct population, and that the pooled data introduced the Wahlund effect. Allele frequencies at individual loci per village population are most likely at Hardy-Weinberg equilibrium. Larger samples per village need to be examined to facilitate a goodness of fit χ2-test between observed and expected frequencies.

Résumé

La variation électrophorétique était déterminée pour huit bandes enzymatiques dans Anophèles arabiensis provenant de quatre villages de la région irriguée de Mwea au Kenya. Sept bandes avaient des allèles polymorphiques dont au moins deux étaient communs. Les fréquences ressemblées des allèles pour les bandes Pgm, β-Had et Odh étaient en équilibre de Hardy-Weinberg, alors que celles de Ao, Idh, Adh, Est-1 et 6-Pgd montraient des déviations significatives. La fréquence des hétérozygotes pour les bandes de Adh, Est-1 et 6-Pgd était la moins attendue alors que pour la bande Ao, il y avait un excès. Une contingeance 2 × 4 du test χ2 pour chaque bande non en équilibre de Hardy-Weinberg indiquait une association entre les fréquences respectives de genes et les villages. L'explication suggérée pour ces observations est que chaque village constitue une population distincte et que les données rassemblées introduisaient l'effet Wahlund. Les fréquences des allèles à une bande individuelle par population de village étaient plus vraisemblablement en équilibre de Hardy-Weinberg. Un plus grand nombre d'échantillons par village est nécessaire pour être en accord avec le test χ2 entre les fréquences observées et celles attendues.

Type
Research Articles
Copyright
Copyright © ICIPE 1987

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