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Silvae Genetica

I consider Silvae Genetica a second tier journal from a researcher point of view, although:

  1. Sometimes it has great articles,
  2. If I had access to a single forest genetics journal I would choose this one, and
  3. It is the best option from a tree breeder’s perspective.

Another good point of this journal is that all its articles (in PDF format) are free to access a year after published.

Abstracts

Short Note: More generalised estimation of between-trait genetic correlations using data from collateral relatives

Burdon, R.D. and Apiolaza, L.A.. 1998. Silvae Genetica 47: 174–175. (PDF paper 73 KB).

Sib-family or clonal data are commonly used to estimate genetic correlations between traits. Usually both traits of a pair are measured on the entire genetic sample, but quite often the respective traits are measured on independent samples from within the genetic groups. Using a method based on analysis of variance, the estimation procedure is generalised to include cases where the two traits are measured on partially overlapping subsamples, provided group size and degree of overlap are constant. This has a clear potential for improving cost-efficiency, especially for pairs of traits that differ widely in heritability and/or costs of measurement.

Optimising early selection using longitudinal data

Apiolaza, L.A., Garrick, D.J., and Burdon, R.D. 2000. Silvae Genetica 49: 195–200. (PDF paper 579 KB).

This study analysed the use of longitudinal data, i.e. repeat ed assessment of the same individuals at different ages, in the context of early selection. Autoregressive relationships, banded correlations and unstructured (‘unsmoothed’) matrices were used to model the additive genetic covariance matrix (G0) for 10 total height measurements of a Pinus radiata open-pollinated progeny test. We examined the effects on response to selection of inferred covariance structure, mass versus combined selection, one or multiple assessments, and two breeding- delay intervals. End results are expressed as predicted average gain per year. The patterns of predicted response to selection vary widely between inferred covariance structures. Considering the autoregressive model (based on logarithm of age ratios between assessments) as an example, the effect of combining information from relatives on response to selection is more important (16% to 41% extra gain) than using extra measurements (2% to 25%), when predicting individual breeding values, although the economics of extra gain vs extra assessment costs must be carefully analysed. It is expected that using multiple assessments could be advisable for datasets with lower genetic autocorrelations. An approximate comparison across covariance models showed the autoregressive model to exhibit the best ability to produce ‘correct’ selections as well as the highest predicted response to selection.

Genetic variation of physical and chemical wood properties of Eucalyptus globulus.

Apiolaza, L.A., Raymond, C.A. and Yeo, B. 2005. Silvae Genetica 54: 160–166.

This study considered the degree of genetic variation for diameter (DBH), basic density (BD), predicted pulp yield (PPY), fibre length (FL), microfibril angle (MFA) and cellulose content (CC) amongst eight subraces of Eucalyptus globulus growing in a field trial in NW Tasmania. There were significant subrace effects for BD, FL and CC. This variation affected the relative profitability of the subraces for pulp production. On average, the most profitable subraces (on NPV/ha over the base population mean) were Strzelecki Ranges ($862.04), Western Otways ($657.80) and Strzelecki Foothills ($576.81). The genetic control (heritability) of variation in DBH, FL and MFA was moderate (0.15 < h2< 0.27), while control for BD, PPY and CC was high (h2> 0.40). Genetic correlations between growth and wood properties were not statistically significant, except for DBHMFA (–0.86). Most genetic correlations amongst wood properties were outside the parametric space (< –1 or >1), but there were significant correlations between BDMFA (–0.70) and PPY-CC (0.82). The empirical response to selection on an index based on a pulp wood objective (which included volume and basic density) resulted in a gain of 4.3% for DBH, 7.9% for BD and marginal changes for all other traits, with a net impact in profit of $1,270/ha. However, future profit calculations will need to consider the effect of FL, MFA and CC on the economics of wood processing to fully evaluate the economic impact of breeding.