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

Abstract

Eucalyptus obliqua L’Hér. is widespread across south-eastern Australia. On the island of Tasmania it has a more-or-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 flow is >150 times the level of seed-mediated gene flow in 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.

Assessing a Bayesian Approach for Detecting Exotic Hybrids between Plantation and Native Eucalypts

“…The PCRs were performed using a QIAGEN Multiplex PCR kit (Hilden, Germany) according to the manufacturer's specifications for 5 L reactions using approximately 5 ng of genomic DNA per reaction. Thermocycler conditions followed Bloomfield et al [53] with annealing temperatures of 59 ∘ C for mix 1, and 58 ∘ C for mix 2 and mix 3. The PCR product was diluted 1 in 10 in H 2 O and then 1 L of that dilution was dried at 50 ∘ C. Fragment separation was undertaken on an ABI3730 DNA analyser (Applied Biosystems Hitachi) by the Australian Genome Research Facility, South Australia.…”

“…The PCR product was diluted 1 in 10 in H 2 O and then 1 L of that dilution was dried at 50 ∘ C. Fragment separation was undertaken on an ABI3730 DNA analyser (Applied Biosystems Hitachi) by the Australian Genome Research Facility, South Australia. Allele scoring followed Bloomfield et al [53]. The assigned genotypes of the 27 repeated samples (which were scored blindly) were compared at each locus to obtain a measure of repeatability (number of allelic errors/number of alleles compared).…”

Diagnosing species decline: a contextual review of threats,causes and future directions for management and conservation of the eastern quoll

“…Work on E. obliqua has focused on characterising distinctive groups in the natural gene pool and found it to be far less diverse that previously thought (Bloomfield et al 2011). This information which will better inform the management and seed transfer guidelines.…”

Development of microsatellites using next-generation sequencing for Acacia crassicarpa

“…Nor was it uncommon, for example Ng et al (2005) found divergence from Hardy-Weinberg equilibrium in 7 of the 15 markers tested in A. mangium. One process that can drive deviation from HardyWeinberg equilibrium is the presence of null alleles, but there was little or no evidence for null microsatellite studies (Bloomfield et al 2011). The markers were also generally easy to score, with the exception of cras13 which required more careful checking due to stutter peaks.…”