Microsatellite and cpDNA variation in island and mainland populations of a regionally rare eucalypt, Eucalyptus perriniana (Myrtaceae)
Damien A. Rathbone A , Gay E. McKinnon A , Brad M. Potts A , Dorothy A. Steane A and René E. Vaillancourt A BA School of Plant Science and Cooperative Research Centre for Forestry, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia.
B Corresponding author. Email: R.Vaillancourt@utas.edu.au
Australian Journal of Botany 55(5) 513-520 https://doi.org/10.1071/BT06203
Submitted: 10 October 2006 Accepted: 1 February 2007 Published: 17 August 2007
Abstract
Eucalyptus perriniana F.Muell. ex Rodway is distributed over a wide geographic range in south-eastern Australia as a series of small and isolated populations. In Tasmania, there are only three known populations that are separated by 511 km from the closest population on mainland Australia, which is one of the largest disjunctions observed for any eucalypt species. This project utilised eight nuclear microsatellites and one chloroplast DNA marker to study the genetic diversity in E. perriniana and determine the affinities between the populations. In all, 302 individuals in nine populations across the whole range of the species were sampled. The overall nuclear microsatellite diversity in E. perriniana (Ht = 0.85), as well as the diversity in each population (He = 0.73), was comparable to that found in widespread eucalypt species that have much larger population sizes. The microsatellites revealed that the isolated Tasmanian populations were significantly differentiated from mainland populations (FST between regions = 0.08), although the mainland Baw Baw population was the most differentiated. Most populations harboured different chloroplast DNA haplotypes, but in general, there were more mutational differences among haplotypes found in Tasmania than between Tasmanian and mainland populations. The Tasmanian populations often shared chloroplast DNA haplotypes with other eucalypts from south-eastern Tasmania. In conclusion, the populations of E. perriniana are genetically variable and significantly differentiated, with geographic separation being a poor predictor of the amount of genetic divergence. The most divergent populations are those in Tasmania and on Mt Baw Baw and their conservation is important to capture the genetic diversity in the species.
Acknowledgements
We thank Rebecca Jones, James Worth, Jules Freeman, Tim Jones and Adam Smolenski for their help. This research was supported by Discovery grants (DP0557260 and DP0664923) from the Australian Research Council.
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