Title
Genetics, Genomics and Genetical Genomics: Analysis of Partial Diallel Designs
Speaker
Lauren McIntyre, Purdue University
Abstract
Classic quantitative Genetics uses breeding designs to assist in inferences about mechanisms of genetic variation. The diallel, and partial diallel is a tool to understanding the nature of phenotypic variation. The generalization of the partial diallel analysis for a problem in wheat breeding, led to the ability to use this design in a genomic context. Microarray technology permits an examination of genetic variation at the level of mRNA abundance. Utilizing a partial diallel design, we present a quantitative description of variation in mRNA abundance in terms of GCA (general combining ability, or additive variance) and SCA (specific combining ability, primarily dominance variance). We test whether features significant for GCA and SCA are randomly distributed across chromosomes, and use a nonparametric approach to demonstrate that the magnitude of the variation is not random for GCA. We find that there is an excess of significant features for SCA on the X chromosome relative to the autosomes, and a paucity of features significant for GCA on the X relative to the autosomes. The overall magnitude of the effects for GCA on the X tends to be lower than on the autosomes, and is contributed by rare alleles of larger effect. This non-random patterning of genetic variation in gene expression data with respect to chromosomal context suggests the action of selection.
