Strong, independent, quantitative genetic control of the timing of vegetative phase change and first flowering in Eucalyptus globulus ssp globulus (Tasmanian Blue Gum)

Analyses of large open-pollinated and controlled-cross field trials of Euca lyptus globulus ssp. globulus show quantitative genetic independence of the times of first flowering and the abrupt change in leaf form. The onset of each of these critical developmental events is under moderate to strong add itive genetic control in this taxon, with individual narrow-sense heritabil ities of 0.4-0.6 and 0.2-0.9, respectively, and little nonadditive genetic control. This strong additive genetic control and the independence of these processes provide the genetic environment for rapid heterochronic microevo lution.