Allozyme variation in 16 natural populations of Faidherbia albida (Del.) A. Chev.

The objectives of this study were (1) to investigate the genetic variabilit y; and (2) to determine the phylogenetic relationship in the leguminous tre e Faidherbia albida through out its range of distribution in East, West and Southern Africa. A total of 16 populations were subjected to enzyme electr ophoresis and 6 enzyme systems (Adh, Mdh, G6pdh, Idh, 6Pgdh, and alpha -Est ) encoded by 12 loci were scored. A total of fifty one different alleles we re detected, with an average of 2.5 alleles per locus. Forty three percent of the loci were polymorphic at a 95% criterion. The average expected heter ozygosity (gene diversity index H-e) was 0.141. All provenances showed sign ificant deviation from Hardy-Weinberg expectation. The UPGMA cluster analys is, based on Modified Rogers distance revealed close similarities between E astern and Southern African provenances, except Debre zeit from Ethiopia, w hich was closest to West African populations than to the East African popul ations. Also, Bignona from West Africa was peculiarly closer to East Africa n provenances. Differentiation of West African populations from Eastern and Southern African provenances was quite evident, emphasising the clinal pat tern of variation in these two major geographical races of F. albida in Afr ica. Wright's F-statistics showed an overall significant deficit of heteroz ygotes, a common feature in mixed mating, entomophilous, widespread species such as F. albida. The dendrogram analysis showed wide separation among th e three Ethiopian provenances indicating a high level of genetic differenti ation and diversity among them.