RESEARCH ARTICLE Genetic (co)variance of ra d t

uniformity, especially the sign and magnitude of its rg. Ge n e t i c s Se lec t ion Evolut ion Sae-Lim et al. Genetics Selection Evolution (2015) 47:46 DOI 10.1186/s12711-015-0122-8practice to reduce heterogeneity in growth performance isJokioinen, FinlandFull list of author information is available at the end of the articleBackground Uniformity of traits depends on an individual’s sensitivity to perturbations in its internal environment and of un-known local micro-environmental factors [1-3]. Additive genetic variance in uniformity is defined as the genetic heterogeneity of the residual variance for a trait [4-6]. Accordingly, less sensitive genotypes have offspring that are more uniform and show a smaller within-family residual variance. In animal production, uniformity is often a desired character because: (1) it indicates pheno-typic robustness and (2) it aids in producing homogeneous animal stocks and uniform food products. Generally, aquatic animals exhibit considerable heterogeneity in growth performance. Large variation in body weight (BW) among individuals reduces fish welfare and decreases the sustainability of the aquaculture industry [7]. A commo