Lack of genetic differentiation between 19 populations from seven taxa of Sutherlandia Tribe: Galegeae, Fabaceae

Horizontal starch gel-electrophoresis was used to examine genetic diversity between geographically isolated populations of Sutherlandia tomentosa, S. frutescens, S. frutescens var. incana, S. microphylla, S. speciosa, S. humilis and S. montana at 18 enzyme coding loci. Astragalus atropilosulus subsp. burkeanus and a Lessertia species were used as outgroups to root dendrograms. Gene product of 32 enzyme coding loci revealed genetic variation at 18 (56.3%) thereof. The percentage of polymorphic loci ranged from 0 to 20.6% (0.95 criterion), values between 1.0 (± 0.00) and 1.3 (± 0.09) were obtained for the mean number of alleles per locus, and average heterozygosity values per locus ranged from 0 to 0.097 (±0.034). The average genetic distance between populations (0.077) was higher than between taxa (0.032); the overlap in the cluster analyses of genetic distance data indicated that Sutherlandia taxa are not easily distinguished genetically. Although preliminary results showed that it was possible to identify some sympatric taxa, the analysis of additional populations annuled this result. There is remarkable lack of agreement between morphological and allozyme patterns within the genus Sutherlandia and the low allozyme differentiation between populations and taxa could be the result of the breeding systems of this genus.