Khoury et al. (Am J Hum Genet 1988;42:89-95 and Am J Epidemiol 1993;137:1241-50) presented an epidemiologic approach to examine genotype-environment interaction in situations where the disease is either present or absent. In this article, the author extends the approach of Khoury et al. to quantitative outcome variables. This extension is relevant for diseases that are extremes on a continuum o...

A simulation study was performed to see whether selection affected quantitative trait loci (QTL) mapping. Populations under random selection, under selection among full-sib families, and under selection within a full-sib family were simulated each with heritability of 0.3, 0.5, and 0.7. They were analyzed with the marker spacing of 10 cM and 20 cM. The accuracy for QTL detection decreased for t...

The scanqtl function, while completely flexible and so suitable for most purposes, is rather cumbersome to use. Our most important additions are the functions addqtl, to scan for a single QTL to be added to a multiple-QTL model, and addpair, to scan for a pair of QTL to be added to a multiple-QTL model. The output of these functions is of the forms produced by scanone and scantwo, respectively,...

Variation in vein position and wing shape of Drosophila melanogaster depends on many genes. In the following, we report the results of a QTL analysis of wing shape in D. melanogaster. We identified QTL responsible for natural variation for wing shape and analyzed their interactions with developmental genetic signaling pathways important for vein positioning. The QTL analysis indicated that the ...

Inferences regarding phylogenetic patterns and constraints on the evolution of characters often can be derived only from comparisons of extant species. If the phylogeny of these species is known, then the mean phenotypes of taxa can be partitioned into heritable phylogenetic effects and nonheritable residual components. Methods are presented for the estimation of phylogenywide means of characte...

The usual analysis of genotype × environment interaction (G × E) is based on the linear regression of genotypic performance on environmental changes (e.g., classic stability analysis). This linear model may often lead to lumping together of the non-linear responses to the whole range of environmental changes from suboptimal and super optimal conditions, thereby lowering the power of detecting G...