title: A general framework for analyzing the genetic architecture of developmental characteristics.
abstract: The genetic architecture of growth traits plays a central role in shaping the growth, development, and evolution of organisms. While a limited number of models have been devised to estimate genetic effects on complex phenotypes, no model has been available to examine how gene actions and interactions alter the ontogenetic development of an organism and transform the altered ontogeny into descendants. In this article, we present a novel statistical model for mapping quantitative trait loci (QTL) determining the developmental process of complex traits. Our model is constructed within the traditional maximum-likelihood framework implemented with the EM algorithm. We employ biologically meaningful growth curve equations to model time-specific expected genetic values and the AR(1) model to structure the residual variance-covariance matrix among different time points. Because of a reduced number of parameters being estimated and the incorporation of biological principles, the new model displays increased statistical power to detect QTL exerting an effect on the shape of ontogenetic growth and development. The model allows for the tests of a number of biological hypotheses regarding the role of epistasis in determining biological growth, form, and shape and for the resolution of developmental problems at the interface with evolution. Using our newly developed model, we have successfully detected significant additive x additive epistatic effects on stem height growth trajectories in a forest tree.
authors.affiliation: Department of Statistics, University of Florida, Gainesville, Florida 32611, USA. rwu@stat.ufl.edu
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
authors.forename: Chang-Xing
authors.initials: CX
authors.lastname: Ma
authors.forename: Min
authors.initials: M
authors.lastname: Lin
authors.forename: George
authors.initials: G
authors.lastname: Casella
mesh_terms: D000465:Algorithms; D005075:Biological Evolution; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D004843:Epistasis, Genetic; D008040:Genetic Linkage; D006128:Growth / Q000235:genetics*; D016015:Logistic Models; D018895:Microsatellite Repeats; D012150:Polymorphism, Restriction Fragment Length; D032107:Populus / Q000235:genetics / Q000254:growth & development; D040641:Quantitative Trait Loci