Isozyme Variation in Eucalyptus nitens and E. denticulata

Abstract

Seed samples from 22 populations across the geographic range ofE. nitens (Deane & Maiden) Maiden s. str. andE. denticulata I.O. Cook & P.Y. Ladiges wereanalysed for isozyme variation and estimation of the genetic distance betweenthe two taxa. Analysis of 12 enzyme systems in 3 buffer systems revealed 12polymorphic and 5 monomorphic loci. The results confirm the distinctiveness ofE. nitens and E. denticulatapreviously reported for morphological characteristics. A single population ofthe related species E. quadrangulata Deane & Maidenwas distinct from, and more heterogeneous than, populations of the other two taxa. The results also show regional genetic variation withinE. nitens that correlates with observed differences inmorphology. Three races were identified: northern and central NSW; southern NSW and Mt Kay in eastern Victoria; Baw Baw Ranges and Central Highlands inVictoria. Geographically isolated populations, particularly from central andnorthern NSW, showed the least genetic variation. Variation was highest in anequivocal population from Mt Gregory, central Victoria, where the distributionof E. nitens overlaps with that ofE. denticulata.