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New trials test fitness of exotic hybrids

bb10-exotic-hybrids

Paul Tilyard sorts exotic E. nitens hybrids at the UTAS nursery.

Paul Tilyard
School of Plant Science
University of Tasmania

The shining gum, Eucalyptus nitens, is native to New South Wales and Victoria, but is a widely planted plantation species in Tasmania.  Shining gum belongs to subgenus Symphyomyrtus and is closely related to the Tasmanian blue gum, Eucalyptus globulus. Of the 29 species of eucalypt in Tasmania, 17 belong to this subgenus.  Studies at the University of Tasmania have shown that E. globulus happily hybridises with numerous other species of subgenus Symphyomyrtus to produce viable hybrid offspring that can survive in the wild.  The question arises, then, as to whether E. globulus' interstate cousin, E. nitens, can also hybridise with other Tasmanian species.  If so, will the exotic hybrid offspring be fit enough to grow and survive to maturity in competition with the native species?

Two trials will be established in late 2009 to investigate the viability of first generation (F1) hybrids between E. nitens and a number of native Tasmanian eucalypts.  Many Tasmanian eucalypt species have populations neighbouring E. nitens plantations.  Robert Barbour (formerly of UTAS) conducted controlled crossing of E. nitens pollen onto many of the Tasmanian Symphyomyrtus species.  In the new field trials, these exotic hybrid seedlings will be paired up with out-crossed pure seedlings from the same mother (native) trees.  The success of the hybrids compared with their respective maternal parent species will provide valuable data on the possible long-term risk of gene flow from plantations into native gene pools.  This is of particular concern with rare species, such as E. perriniana.  Other native species included in the new hybrid trials include E. ovata, E. archeri, E. subcrenulata, E. viminalis, E. vernicosa, E. barberi, E. brookeriana, E. gunnii, E. johnstonii, E. morrisbyi  and E. cordata.

Biobuzz issue ten, December 2009