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Analysis of a hybrid swarm between Eucalyptus risdonii Hook. f. and E. amygdalina Labill


Potts, BM and Reid, JB, Analysis of a hybrid swarm between Eucalyptus risdonii Hook. f. and E. amygdalina Labill , Australian Journal of Botany, 33, (5) pp. 543-562. ISSN 0067-1924 (1985) [Refereed Article]

Copyright Statement

Copyright 1985 CSIRO

DOI: doi:10.1071/BT9850543


E. risdonii is a rare Tasmanian endemic which occurs as a series of small distunct populations within a more-or-less continuous population of a closely related species, E. amygdalina. In localized areas (e.g. Risdon, Tasmania), patches of high phenotypic diversity are encountered, with individuals encompassing the complete phenotypic range between these two species. Progeny trials indicate a large heritable component to this variation. Open-pollinated progenies from intermediate mothers exhibit greater variability than those from either pure species, which strongly suggests that these intermediate phenotypes are a result of hybridization. Progenies from pure species mothers near a hybrid swarm are more variable than those from pure stands. There is a greater proportion of seedlings which match the artificially produced F1 in open-pollinated progenies from E. amygdalina than from E. risdonii mothers. In addition, progenies from intermediate mothers show a bias toward E. risdonii types, which implies that they are predominantly outcrossing to E. risdonii. This evidence suggests an asymmetrical flow of genes by pollen migration from E. risdonii into the hybrid swarm and surrounding E. amygdalina.

Little difference in seedling vigour or mortality occurred between seedlings from the various parental phenotypes, although differences in seed output per capsule and germination were apparent. The specific identity of >E. risdoniiE. amygdalina is usually maintained in parapatry by a range of mechanisms including their specific ecological preference, reduced hybrid fitness and differences in flowering phenology. The reasons for the major zones of hybridization occurring at boundaries on ridge tops as opposed to those on the dry slopes are discussed.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Plant biology not elsewhere classified
Objective Division:Plant Production and Plant Primary Products
Objective Group:Forestry
Objective Field:Native forests
UTAS Author:Potts, BM (Professor Brad Potts)
UTAS Author:Reid, JB (Professor Jim Reid)
ID Code:87044
Year Published:1985
Web of Science® Times Cited:47
Deposited By:Plant Science
Deposited On:2013-11-06
Last Modified:2013-12-02

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