All Content © CRC for Forestry 2007

Biobuzz 6 - What's Been On - Paul Nevill's Poster Abstract

Genome sharing patterns in south-east Australian eucalypts


a The University of Melbourne, The School of Forest and Ecosystem Science, and Cooperative Research Centre for Forestry, Water Street, Creswick, Victoria 3363, Australia.

bThe School of Forest and Ecosystem Science, The University of Melbourne, and Cooperative Research Centre for Forestry, Parkville, Victoria 3010, Australia.

Keywords: introgression, Eucalyptus, reticulate evolution, refugia, hybrid, phylogeography.

Interspecific hybridization and introgression appears to have played an important role in the evolution of Eucalyptus species. Previous studies, mostly on species in subgenus Symphyomyrtus, have found high levels of intraspecific chloroplast DNA (cpDNA) polymorphism and extensive sharing of chloroplast haplotypes between species within regions. Similar to Quercus, geographical location is more important than species when it comes to determining chloroplast type in subgenus Symphyomyrtus. Less was known about the extent of cpDNA sharing between species in subgenus Eucalyptus, as well as the extent of sharing of the nuclear genome between Eucalyptus species. In this study we examined sharing of the nuclear and cytoplasmic genome between 200 individuals from 10 species at 25 locations using nuclear and chloroplast microsatellite markers. Preliminary results indicate that cpDNA haplotypes are extensively shared between subgenus Eucalyptus species. Twenty five different haplotypes were found in 10 different species at 25 locations where the species occurred together. All species at a location were more likely to share exact haplotypes in areas thought to have been treeless during the Last Glacial Maximum (LGM) than the same species in hypothesised glacial refugia. Preliminary results on the sharing of the nuclear genome indicate extensive sharing of alleles between some species, and little sharing between other species. Further work will help to elucidate the patterns of sharing of both nuclear and cytoplasmic genetic markers.