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Stringy bark population research makes front cover of AJB

In the scientific equivalent to a centrefold, Eucalyptus obliqua has made the front cover of Australian Journal of Botany.  Illustrating Justin Bloomfield's article on E. obliqua population structure in Tasmania is a stunning photograph of an E. obliqua canopy in Tasmania's southern forests taken by UTAS lecturer in Plant Science, Dr Robert Wiltshire.

eucalyptus obliqua

Eucalyptus obliqua dominates a Tasmanian wet sclerophyll forest (Image: Robert Wiltshire)



Justin was a CRC-funded honours student at UTAS in 2008 and has been continuing his research into E. obliqua population genetics in order to provide fundamental genetic information to assist with formulating effective management plans for the genetic resource in Tasmania.  Justin used highly variable selectively neutral molecular markers (microsatellites) to show that there is very little (selectively neutral) molecular variation in nuclear DNA across populations of the species in Tasmania.  This means that there is a lot of gene flow between populations.  Even in two sites in southern Tasmania where there are marked differences in quantitative traits across steep environmental gradients (Wilkinson 2008), there is no variation in the selectively neutral markers.  Hence, the observed quantitative genetic variation at these locations is most likely maintained by natural selection.  While nuclear DNA markers are inherited from both parents, chloroplast DNA is inherited only from the mother.  Using chloroplast microsatellites Justin showed that pollen (as opposed to seed) is probably the main mode of gene flow in the species.  He also identified an east-west geographic partitioning of chloroplast DNA lineages among Tasmanian E. obliqua populations, suggesting that, historically, E. obliqua has undergone range contraction and expansion.  The implications of these results for silviculture are discussed in the paper.

References

Bloomfield JA, Nevill P, Potts BM, Vaillancourt RE, Steane DA (2011) Molecular genetic variation in a widespread forest tree species Eucalyptus obliqua (Myrtaceae) on the island of Tasmania.  Australian Journal of Botany 59: 226-237. [Access publication]

Wilkinson GR (2008) Population differentiation within Eucalyptus obliqua: implications for regeneration success and genetic conservation in production forests.  Australian Forestry 71: 4-15.

Biobuzz issue fourteen, May 2011