Adaptive scoping: balancing short- and long-term genetic gain in plant breeding

Abstract

Truncation selection is often used to rapidly achieve short-term genetic gain within a breeding program. Unfortunately, it is also associated with the loss of favorable QTL alleles in the breeding population, causing a premature convergence to sub-optimal genetic values. Parental selection strategies such as the scoping method, the population merit method, and optimal cross selection have been proposed to preserve genetic variation in the breeding population and thus maximize genetic gain in the long term. Nevertheless, for economic reasons, breeders are often interested to maximize the genetic gain in a shorter time frame. We propose a new selection strategy, named the adaptive scoping method, that aims at maximizing the genetic gain within a specific, predefined time frame. Throughout this time frame, the adaptive scoping method progressively changes its selection strategy: during the initial breeding cycles, it attempts to maximally preserve genetic variation, whereas in later breeding cycles, it prioritizes the increase of the genetic value. We demonstrate through simulation studies that the adaptive scoping method is able to maximize the genetic gain for a wide range of time frames and that it outperforms the original scoping method, both in the short and in the long term.