Temporal variation of allele frequencies in a natural population of wild Vigna unguiculata

Abstract

Temporal variation in allele frequencies in a natural population of wild Vigna unguiculata was studied by making monthly collections of seeds overatwo-year period. Usingstarch gelelectrophoresis, four outof sevenloci analysed wereshown to be polymorphic (Enp, Fdh, Fle 3 and Pgd 2). These four loci showed significant variation in allele frequencies over time. Changes in population structure over time were analysed using F-statistic estimators. Although heterogeneity was evident between loci, the analysis showed significant differentiation among months within a year for all polymorphic loci. Fixation indexes wereall positive and statistically different from zero, highlighting asignificant departure from random mating. Using analysis of variance (ANOVA), the pattern of inbreeding (f) showed significant changes over time (season); among the polymorphic loci, Enp most strongly contributed to this significance. Significant correlations were found between allele frequencies at different loci. The monthly average gene diversity (He) and allele frequencies at the Enp locus were found to be significantly correlatedwithweatherconditions(temperatureandrainfalldistribution).Theseallelefrequencydeviationsovertimecanbe attributed to changes in pollinator behaviour, and frequent genetic bottlenecks that are associated with changes in environmental conditions.