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Molecular genetic variation in a widespread forest tree species Eucalyptus obliqua (Myrtaceae) on the island of Tasmania


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Bloomfield, JA, Nevill, P, Potts, BM, Vaillancourt, RE and Steane, DA 2011 , 'Molecular genetic variation in a widespread forest tree species Eucalyptus obliqua (Myrtaceae) on the island of Tasmania' , Australian Journal of Botany, vol. 59, no. 3 , pp. 226-237 , doi: 10.1071/BT10315.

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Eucalyptus obliquaL’Hér. is widespread across south-eastern Australia.Onthe island of Tasmania it has a moreor-
less continuous distribution across its range and it dominates much of the wet sclerophyll forest managed for forestry
purposes. To understand better the distribution of genetic variation in these native forests we examined nuclear microsatellite
diversity in 432 mature individuals from 20 populations of E. obliqua across Tasmania, including populations from each
end of three locally steep environmental gradients. In addition, chloroplast microsatellite loci were assessed in 297
individuals across 31 populations. Nuclear microsatellite diversity values in E. obliqua were high (average HE = 0.80) and
inbreeding coefficients low (average F = 0.02) within these populations. The degree of differentiation between populations
was very low (FST = 0.015). No significant microsatellite differentiation could be found across three locally steep
environmental gradients, even though there is significant genetic differentiation in quantitative traits. This suggests that
the observed quantitative variation is maintained by natural selection. Population differentiation based on chloroplast
haplotypes was high (GST = 0.69) compared with that based on nuclear microsatellites, suggesting that pollen-mediated
gene flowis >150 times the level of seed-mediated gene flowin this animal-pollinated species; hence, pollen is likely to be the
main mode of gene flow countering selection along local environmental gradients. Implications of these results for
silvicultural practices are discussed.

Item Type: Article
Authors/Creators:Bloomfield, JA and Nevill, P and Potts, BM and Vaillancourt, RE and Steane, DA
Keywords: Eucalyptus obliqua; Tasmania; Molecular genetics; forest genetics;
Journal or Publication Title: Australian Journal of Botany
ISSN: 0067-1924
DOI / ID Number: 10.1071/BT10315
Additional Information:

Copyright © CSIRO 2011

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