Hologenomic interactions promote the higher-order evolvability of phenotypic complexity.

Hologenomic interactions expand heritable variation and promote phenotypic complexity, influencing evolutionary trajectories in the holobiont system.

• Why it matters: Understanding the origin and inheritance of complex phenotypes is limited by models focusing only on host genomes, neglecting multigenome interactions that may be crucial for evolutionary innovation.
• What they did: The authors propose a framework that treats multigenome interactions within the holobiont as central to the genotype-phenotype map, suggesting these interactions increase mechanisms for heritable variation and trait development.
• The result: This approach indicates that hologenomic targets of selection are essential for comprehending many evolutionary pathways and novelties, offering hypotheses and methods to quantify their macroevolutionary impacts.