Genetic differentiation and phenetic relatedness among seven species of the Macrozamia plurinervia complex (Zamiaceae)

Starch gel electrophoresis was employed to estimate the levels of genetic variation among seven species of the Macrozamia plurinervia complex (Zamiaceae) from eastern Australia. A total of 295 specimens were assayed for 11 enzyme systems coded by 17 loci. The mean number of alleles per locus (A) and proportion of polymorphic loci (P) averaged over seven species were 1.5 and 36.58%. The average observed and expected heterozygosity (H o, H e) were 0.08 and 0.11, respectively, which falls within the range of other Macrozamia species. In the case of Macrozamia cranei and M. machinii, they displayed strong genetic similarity, but were markedly different to the other five species. Among the seven species, M. conferta was the most and M. fearnsidei was the least variable. A fixed allele difference was found only in M. fearnsidei where locus Menadione reductase (MR2) was absent. Along with this, numbers of rare alleles were found in various species, which would facilitate distinguishing one species from another. Based on genetic identity/distance, the Macrozamia species were clustered into two groups. Although the taxa are undoubtedly closely related, the results reinforce current taxonomic concepts based on morphological characters.