Genetics of Eucalypts: traps and opportunities

Eucalypts are amongst the most planted hardwoods in the world (Doughty 2000). They are native to Australia and islands to its north (Ladiges et al. 2003) where they occupy diverse ecological habitats ranging from sea level to the alpine tree line, from high rainfall to semi-arid zones, and from the tropics to latitudes as high as 43¬¨‚àû south (Williams and Woinarski 1997). In habit they vary from shrubs and multi-stemmed mallees, to giant trees (Hickey et al. 2000; Nicolle 2006), and include the tallest flowering plants on earth (Eucalyptus regnans - 99.6 metres, http://www.gianttrees.com.au/). They are generally sclerophyllous, and adapted to low nutrient soils and fire (Ashton 2000; Eldridge et al. 1993; Florence 1996). In the broad-sense, eucalypts encompass species of the genera Eucalyptus L‚ÄövÑvºHerit., Corymbia Hill and Johnson and Angophora Cav. (Ladiges 1997; Appendix 1). A key feature of the majority of Eucalyptus (sensu stricta) and Corymbia (bloodwoods) is the fusion of either the petals and/or sepals to form an operculum from which the eucalypts derive their name (Eldridge et al. 1993; Ladiges 1997). The latest formal taxonomic revision of eucalypts (Brooker 2000) recognizes just over 700 species that belong to 13 main evolutionary lineages (subgenera/genera; Appendix 1), and EUCLID (Euclid 2006 - an important electronic resource for practitioners) lists 894 eucalypt taxa. The major subgenera exhibit different ecological and reproductive characteristics (Florence 1996; Ladiges 1997; Harwood 2011 this volume) and closely related species are usually ecologically differentiated (Florence 1996; Williams and Woinarski 1997).