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Abstract

Genetic parameters for stem diameter and wood
density were compared at selection (4–5 years) and harvest
(16–17 years) age in an open-pollinated progeny trial of
Eucalyptus globulus in Tasmania (Australia). The study
examined 514 families collected from 17 subraces of E.
globulus. Wood density was assessed on a subsample of
trees indirectly using pilodyn penetration at both ages and
directly by core basic density at harvest age. Significant
additive genetic variance and narrow-sense heritabilities
(h2
op) were detected for all traits. Univariate and multivariate
estimates of heritabilities were similar for each trait except
harvest-age diameter. Comparable univariate estimates of
selection- and harvest-age heritabilities for diameter
masked changes in genetic architecture that occurred with
stand development, whereby the loss of additive genetic
variance through size-dependent mortality was countered
by the accentuation of additive genetic differences among
survivors with age. Regardless, the additive genetic (ra) and
subrace (rs) correlations across ages were generally high for
diameter (0.95 and 0.61, respectively) and pilodyn penetration
(0.77 and 0.96), as were the correlations of harvestage
core basic density with selection- and harvest-age
pilodyn (ra −0.83, −0.88; rs −0.96, −0.83). While rs
between diameter and pilodyn were close to zero at both
ages, there was a significant change in ra from adverse at
selection age (0.25) to close to zero (−0.07) at harvest age.
We argue that this change in the genetic correlation reflects
a decoupling of the genetic association of growth and wood
density with age. This result highlights the need to validate
the use of selection-age genetic parameters for predicting
harvest-age breeding values.

Item Type:	Article
Authors/Creators:	Stackpole, DJ and Vaillancourt, RE and Aguigar, M and Potts, BM
Keywords:	Genetic correlation . Density. Eucalyptus globulus
Journal or Publication Title:	Tree Genetics & Genomes
ISSN:	1614-2942
DOI / ID Number:	https://doi.org/10.1007/s11295-009-0239-4
Additional Information:	The original publication is available at www.springerlink.com NB: Third authors last name is Aguiar (as entered here) not Aguigar as shown on the PDF. We will try to correct this with the journal.
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