Epistasis and heterosis

摘要: Traditionally heterosis has been attributed to dominance interactions, particularly overdominance and the masking of deleterious alleles; however there are several other possible causes of heterosis. F. W. Schnell and C. C. Cockerham modeled the more general case of multiplicatively acting gene effects, and found that as with interactions among traits, additive by additive epistasis resulting from multiplicatively acting gene effects can lead to heterosis. The additive effects or breeding values are the sum of the average effects of alleles. The average effect of an allele is the effect of an allele on the phenotype measured as a deviation from the population mean. This chapter discusses one of the consequences of inbreeding and hybridization in systems with epistasis. Inbreeding depression and heterosis inevitably require some form of gene interaction. J. M. Cheverud and E. J. Routman identify two concepts …