MGV3704 Genética Quantitativa Aula 12

This lecture, part of a quantitative genetics course, focuses on the Comstock and Robinson Design 1 for structuring populations in plant breeding. The instructor explains how to derive families using multiple types of relationships, specifically using a hierarchical design with males and females. He contrasts this with simpler designs like half-sib or full-sib families, emphasizing that Design 1 creates both full-sib and half-sib relationships, which complicates the estimation of genetic variances. The lecture reviews the four fundamental principles of quantitative genetics: decomposition of genotypic variance, partitioning of variance, resemblance between relatives, and the equality of between-family variance and within-family covariance. However, the fourth principle is violated in Design 1 because families are related. The instructor then shows how to partition the family effect into male and female within male effects, and how to derive expected mean squares. He explains the statistical tests for the significance of variance components and the genetic interpretation of covariances between relatives, leading to equations that can be solved to estimate additive and dominance variance. The lecture emphasizes understanding the underlying principles rather than just using software, and it sets the stage for further designs like Design 2 and diallels.