Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
Koffler Scientific Reserve, University of Toronto, Toronto, ON, Canada.
Mol Ecol. 2017 Nov;26(21):5869-5871. doi: 10.1111/mec.14370.
The maintenance of genetic variation in the benefits provided by mutualists is an evolutionary puzzle (Heath & Stinchcombe, ). Over time, natural selection should favour the benefit strategy that confers the highest fitness, eroding genetic variation in partner quality. Yet abundant genetic variation in partner quality exists in many systems (Heath & Stinchcombe, ). One possible resolution to this puzzle is that the genetic identity of both a host and its partner affects the benefits each mutualist provides to the other, a pattern known as a genotype-by-genotype interaction (Figure ). Mounting evidence suggests that genotype-by-genotype interactions between partners are pervasive at the phenotypic level (Barrett, Zee, Bever, Miller, & Thrall, ; Heath, ; Hoeksema & Thompson, ). Ultimately, however, to link these phenotypic patterns to the maintenance of genetic variation in mutualisms we need to answer two questions: How much variation in mutualism phenotypes is attributable to genotype-by-genotype interactions, and what mutualistic functions are influenced by each partner and by the interaction between their genomes? In this issue of Molecular Ecology, Burghardt et al. (2017) use transcriptomics to address both questions in the legume-rhizobia mutualism.
共生体所提供的益处中的遗传变异的维持是一个进化难题（Heath & Stinchcombe，）。随着时间的推移，自然选择应该有利于赋予最高适应性的利益策略，从而侵蚀合作伙伴质量的遗传变异。然而，在许多系统中都存在大量的合作伙伴质量的遗传变异（Heath & Stinchcombe，）。这个难题的一个可能解决方案是，宿主及其伴侣的遗传身份都会影响彼此提供的互惠利益，这种模式被称为基因型-基因型相互作用（图）。越来越多的证据表明，合作伙伴之间的基因型-基因型相互作用在表型水平上普遍存在（Barrett、Zee、Bever、Miller 和 Thrall，；Heath，；Hoeksema 和 Thompson，）。然而，为了将这些表型模式与共生关系中遗传变异的维持联系起来，我们需要回答两个问题：共生体表型的变异有多少归因于基因型-基因型相互作用，以及哪些共生功能受到每个合作伙伴以及它们基因组之间相互作用的影响？在本期的《分子生态学》中，Burghardt 等人（2017 年）使用转录组学来解决豆科植物-根瘤菌共生关系中的这两个问题。
