Evolutionary biologists typically envision a trait’s genetic basis and fitness effects occurring within a single species. However, traits can be determined by and have fitness consequences for interacting species, thus evolving in multiple genomes. This is especially likely in mutualisms, where species exchange fitness benefits and can associate over long periods of time. Partners may experience evolutionary conflict over the value of a multi-genomic trait, but such conflicts may be ameliorated by mutualism’s positive fitness feedbacks. Here, we develop a simulation model of a host–microbe mutualism to explore the evolution of a multi-genomic trait. Coevolutionary outcomes depend on whether hosts and microbes have similar or different optimal trait values, strengths of selection and fitness feedbacks. We show that genome-wide association studies can map joint traits to loci in multiple genomes and describe how fitness conflict and fitness feedback generate different multi-genomic architectures with distinct signals around segregating loci. Partner fitnesses can be positively correlated even when partners are in conflict over the value of a multi-genomic trait, and conflict can generate strong mutualistic dependency. While fitness alignment facilitates rapid adaptation to a new optimum, conflict maintains genetic variation and evolvability, with implications for applied microbiome science.

中文翻译：

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到底是谁的特点？共生关系中联合表型和遗传结构的共同进化

进化生物学家通常设想一个性状的遗传基础和适应度效应发生在单个物种中。然而，性状可以由相互作用的物种决定并对其产生适应性影响，从而在多个基因组中进化。这在共生关系中尤其有可能，在这种共生关系中，物种交换健康益处并可以长期联系。合作伙伴可能会因多基因组特征的价值而经历进化冲突，但这种冲突可能会通过互惠主义的积极适应反馈得到缓解。在这里，我们开发了一个宿主-微生物共生的模拟模型，以探索多基因组性状的进化。共同进化的结果取决于宿主和微生物是否具有相似或不同的最佳性状值、选择强度和适应度反馈。我们表明，全基因组关联研究可以将联合特征映射到多个基因组中的位点，并描述适应度冲突和适应度反馈如何产生不同的多基因组架构，并在分离基因座周围产生不同的信号。即使当合作伙伴在多基因组特征的价值上发生冲突时，合作伙伴的适应性也可以呈正相关，并且冲突会产生强烈的互惠依赖。虽然适应度对齐有助于快速适应新的最佳状态，但冲突保持遗传变异和可进化性，对应用微生物组科学具有影响。即使当合作伙伴在多基因组特征的价值上发生冲突时，合作伙伴的适应性也可以呈正相关，并且冲突会产生强烈的互惠依赖。虽然适应度对齐有助于快速适应新的最佳状态，但冲突保持遗传变异和可进化性，对应用微生物组科学具有影响。即使当合作伙伴在多基因组特征的价值上发生冲突时，合作伙伴的适应性也可以呈正相关，并且冲突会产生强烈的互惠依赖。虽然适应度对齐有助于快速适应新的最佳状态，但冲突保持遗传变异和可进化性，对应用微生物组科学具有影响。