From Individual to Stand Performance in Hybrids: Challenging the Optimal Parental Genetic Distance

Hybridization, the interbreeding of distinct genotypes, drives evolutionary processes like speciation and adaptation, potentially via phenotypic transgression, where hybrids exhibit novel traits. In crop breeding, research has largely focused on optimizing heterosis to enhance hybrid performance, particularly for traits such as biomass. It is only recently that the ecological implications of hybridization have been considered, highlighting hybridization as a biotic interaction occurring within populations and communities. This shift raises fundamental questions about whether hybrid performance shows consistent patterns across individual and population scales, particularly regarding predictions based on parental genetic distance. Here, we address this question by examining Arabidopsis thaliana F2 hybrids across a wide range of genetic distances, to compare hybrid performance at individual and stand levels. Our results reveal scale-dependent patterns: individual performance peaks at intermediate parental genetic distances, while stand-level performance increases with genetic divergence, particularly in hybrids between relict and non-relict lineages. These results underscore the importance of scale when evaluating hybrid performance, as plant-plant interactions at the group level can alter the collective outcomes of individual performance. Finally, this framework underscores the importance of integrating individual and population perspectives to better understand the outcomes and potential applications of hybridization.