Tasmania is a natural laboratory for investigating the evolutionary processes of the Quaternary. It is a large island lying 40-44° S, which was repeatedly glaciated and linked to southeastern continental Australia during the Quaternary. Climate change promoted both the isolation of species in glacial refugia, and an exchange between Tasmanian and mainland floras. Eucalyptus is a complex and diverse genus, which has increased in abundance in Australia over the past 100 kyr, probably in response to higher fire frequency. Morphological evidence suggests that gene flow may have occurred between many eucalypt species after changes in their distribution during the Quaternary. This paper summarizes recent genetic evidence for migration and introgressive hybridization in Tasmanian Eucalyptus. Maternally inherited chloroplast DNA reveals a long-term persistence of eucalypts in southeastern Tasmanian refugia, coupled with introgressive hybridization involving many species. Detailed analysis of the widespread species Eucalyptus globulus suggests that migration from mainland Australia was followed by introgression involving a rare Tasmanian endemic. The data support the hypothesis that changes in distribution of interfertile species during the Quaternary have promoted reticulate evolution in Eucalyptus.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Genetics
Research Field:	Molecular Evolution
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Native Forests
Author:	McKinnon, GE (Dr Gay McKinnon)
Author:	Jordan, GJ (Associate Professor Greg Jordan)
Author:	Vaillancourt, RE (Professor Rene Vaillancourt)
Author:	Steane, DA (Dr Dorothy Steane)
Author:	Potts, BM (Professor Brad Potts)
ID Code:	30606
Year Published:	2004
Web of Science® Times Cited:	81
Deposited By:	Plant Science
Deposited On:	2004-08-01
Last Modified:	2007-10-11
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