Issue |
Genet. Sel. Evol.
Volume 35, Number 1, January-February 2003
|
|
---|---|---|
Page(s) | 3 - 20 | |
DOI | https://doi.org/10.1051/gse:2002033 |
DOI: 10.1051/gse:2002033
On the need for a control line in selection experiments: A likelihood analysis
Daniel Sorensen, Bernt Guldbrandtsen and Just JensenDepartment of Animal Breeding and Genetics, Danish Institute of Agricultural Sciences, PO Box 50, 8830 Tjele, Denmark
(Received 8 March 2002; accepted 5 August 2002)
Abstract
The question of whether selection experiments ought to include a
control line, as opposed to investing all facilities in a single
selected line, is addressed using a likelihood perspective. The
consequences of using a control line are evaluated under two
scenarios. In the first one, environmental trend is modeled and
inferred from the data. In this case, a control line is shown to be
highly beneficial in terms of the efficiency of inferences about
heritability and response to selection. In the second scenario,
environmental trend is not modeled. One can imagine that a previous
analysis of the experimental data had lent support to this decision.
It is shown that in this situation where a control line may seem
superfluous, inclusion of a control line can result in minor gains
in efficiency if a high selection intensity is practiced in the selected
line. Further, if there is a loss, it is moderately small. The results
are verified to hold under more complicated data structures via
Monte Carlo simulation. For completeness, divergent selection designs
are also reviewed, and inferences based on a conditional and full likelihood
approach are contrasted.
Key words: selection / design of selection experiments / heritability / maximum likelihood estimation
Correspondence and reprints: Daniel Sorensen
e-mail: Daniel.Sorensen@agrsci.dk
© INRA, EDP Sciences 2003