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The risk of pollen-mediated gene flow from exotic Corymbia plantations into native Corymbia populations in Australia

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Barbour, RC and Crawford, AC and Henson, M and Lee, DJ and Potts, BM and Shepherd, M (2008) The risk of pollen-mediated gene flow from exotic Corymbia plantations into native Corymbia populations in Australia. Forest Ecology and Management, 256 (1- 2). pp. 1-19. ISSN 0378-1127

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Abstract

Sectors of the forest plantation industry in Australia are set to expand in the near future using species or hybrids of the spotted gums (Corymbia, Section Politaria). Plantations of these taxa have already been introduced across temperate and subtropical Australia, representing locally exotic introductions from native stands in Queensland and New South Wales. A literature review was undertaken to provide insights into the potential for pollen-mediated gene flow from these plantations into native populations. Three factors suggest that such gene flow is likely; (1) interspecific hybridisation within the genus has frequently been recorded, including between distantly related species from different sections, (2) apparent high levels of vertebrate pollinator activity may result in plantation pollen being moved over hundreds of kilometres, (3)much of the plantation estate is being established among closely related taxa and therefore few barriers to gene flow are expected. Across Australia, 20 of the 100 native Corymbia taxa were found to have regional level co-occurrence with plantations. These were located most notably within regions of north-east New South Wales and south-east Queensland, however, co-occurrence was also found in south-west Western Australia and eastern Victoria. The native species found to have cooccurrence were then assessed for the presence of reproductive barriers at each step in the process of gene flow thatmay reduce the number of species at risk even further. The available data suggest three risk categories exist for Corymbia. The highest risk was for gene flow from plantations of spotted gums to native populations of spotted gums. This was based on the expected limited existence of pre- and postzygotic barriers, substantial long-distance pollen dispersal and an apparent broad period of flowering in Corymbia citriodora subsp. variegata plantations. The following risk category focussed on gene flow from Corymbia torelliana C. c. variegata hybrid plantations into native C. c. variegata, as the barriers associated with the production and establishment of F1 hybrids have been circumvented. For the lowest risk category, Corymbia plantations may present a risk to other non-spotted gum species, however, further investigation of the particular cross-combinations is required. A list of research directions is provided to better quantify these risks. Empirical data will need to be combined within a risk assessment framework that will not only estimate the likelihood of exotic gene flow, but also consider the conservation status/ value of the native populations. In addition, the potential impacts of pollen flow from plantations will need to be weighed up against their various economic and environmental benefits.

Item Type: Article
Keywords: Biological invasions Exotic species Plantation forestry Off-site impacts Genetic pollution Genetic contamination
Journal or Publication Title: Forest Ecology and Management
Page Range: pp. 1-19
ISSN: 0378-1127
Identification Number - DOI: 10.1016/j.foreco.2008.03.028
Additional Information: The definitive version is available at http://www.sciencedirect.com
Date Deposited: 23 Jun 2008 04:01
Last Modified: 18 Nov 2014 03:43
URI: http://eprints.utas.edu.au/id/eprint/6798
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