Abstract
Accurate inference of relatedness between individuals in breeding population contributes to the precision of genetic parameter estimates, effectiveness of inbreeding management and the amount of genetic progress delivered from breeding programs. Pedigree reconstruction has been proven to be an efficient tool to correct pedigree errors and recover hidden relatedness in open pollinated progeny tests but the method can be limited by the lack of parental genotypes and the high proportion of alien pollen from outside the breeding population. Our study investigates the efficiency of sib-ship reconstruction in an advanced breeding population of Eucalyptus nitens with only partially tracked pedigree. The sib-ship reconstruction allowed the identification of selfs (4% of the sample) and the exploration of their potential effect on inbreeding depression in the traits studied. We detected signs of inbreeding depression in diameter at breast height and growth strain while no indications were observed in wood density, wood stiffness and tangential air-dry shrinkage. After the application of a corrected sib-ship relationship matrix, additive genetic variance and heritability were observed to increase where signs of inbreeding depression were initially detected. Conversely, the same genetic parameters for traits that appeared to be free of inbreeding depression decreased in size. It therefore appeared that greater genetic variance may be due, at least in part, to contributions from inbreeding in these studied populations rather than a removal of inbreeding as is traditionally thought.
Highlights
Heritability is a measure of the proportion of phenotypic variance explained by genetic factors and is built on the principle of resemblance between relatives [1]
We investigated the effect of recovered relatedness on the precision of genetic parameter estimates in both univariate and multivariate genetic analysis
Since there is the assumption that the selfing reduces genetic variance [42], the statistical significance of differences between means was tested by a Welch’s t-test [40] which is an appropriate alternative when the variance equality assumption is not met
Summary
Heritability is a measure of the proportion of phenotypic variance explained by genetic factors and is built on the principle of resemblance between relatives [1]. Narrow-sense heritability is an important parameter for tree breeding programs as it represents the portion of variation that can be transmitted to the progeny. Accurate inference of the relationship among individuals in a breeding population is essential for reliable evaluation of genetic factors contributing to phenotypic variability. Relationship estimates are based on the probability that alleles from two randomly sampled individuals in the population are identical copies of recent. Sib-ship reconstruction in advanced breeding populations these authors are articulated in the ‘author contributions’ section
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