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Heterosis may result in selection favouring the products of long-distance pollen dispersal in Eucalyptus


Costa e Silva, J and Potts, BM and Lopez, GA, Heterosis may result in selection favouring the products of long-distance pollen dispersal in Eucalyptus, PLoS ONE, 9, (4) Article e93811. ISSN 1932-6203 (2014) [Refereed Article]


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Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)

DOI: doi:10.1371/journal.pone.0093811


Using native trees from near the northern and southern extremities of the relatively continuous eastern distribution of Eucalyptus globulus in Tasmania, we compared the progenies derived from natural open-pollination (OP) with those generated from within-region and long-distance outcrossing. Controlled outcrossing amongst eight parents - with four parents from each of the northern and southern regions - was undertaken using a diallel mating scheme. The progeny were planted in two field trials located within the species native range in southern Tasmania, and their survival and diameter growth were monitored over a 13-year-period. The survival and growth performances of all controlled cross types exceeded those of the OP progenies, consistent with inbreeding depression due to a combination of selfing and bi-parental inbreeding. The poorer survival of the northern regional (♀NN) outcrosses compared with the local southern regional outcrosses (♀SS) indicated differential selection against the former. Despite this mal-adaptation of the non-local ♀NN crosses at both southern sites, the survival of the inter-regional hybrids (♀NS and ♀SN) was never significantly different from that of the local ♀SS crosses. Significant site-dependent heterosis was detected for the growth of the surviving long-distance hybrids. This was expressed as mid-parent heterosis, particularly at the more northern planting site. Heterosis increased with age, while the difference between the regional ♀NN and ♀SS crosses remained insignificant at any age at either site. Nevertheless, the results for growth suggest that the fitness of individuals derived from long-distance crossing may be better at the more northern of the planting sites. Our results demonstrate the potential for early-age assessments of pollen dispersal to underestimate realised gene flow, with local inbreeding under natural open-pollination resulting in selection favouring the products of longer-distance pollinations. Indeed, heterosis derived from long-distance pollinations may be sufficient to counter local mal-adaptation, at least in the first generation.

Item Details

Item Type:Refereed Article
Keywords:gene flow, quantitative genetics, genetics, Eucalyptus globulus, heterosis
Research Division:Biological Sciences
Research Group:Genetics
Research Field:Genetics not elsewhere classified
Objective Division:Plant Production and Plant Primary Products
Objective Group:Forestry
Objective Field:Hardwood plantations
UTAS Author:Potts, BM (Professor Brad Potts)
UTAS Author:Lopez, GA (Mr Gustavo Lopez)
ID Code:98307
Year Published:2014
Funding Support:Australian Research Council (LP0884001)
Web of Science® Times Cited:126
Deposited By:Plant Science
Deposited On:2015-02-11
Last Modified:2017-11-03
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