Ecological niche breadth and the mechanisms facilitating its evolution are fundamental to understanding adaptation to changing environments, persistence of generalist and specialist lineages and the formation of new species. Woody substrates are structurally complex resources utilized by organisms with specialized decay machinery. Wood-decaying fungi represent ideal model systems to study evolution of niche breadth, as they vary greatly in their host range and preferred decay stage of the substrate. In order to dissect the genetic basis for niche specialization in the invasive brown rot fungus Serpula lacrymans, we used phenotyping and integrative analysis of phylogenomic and transcriptomic data to compare this species to wild relatives in the Serpulaceae with a range of specialist to generalist decay strategies. Our results indicate specialist species have rewired regulatory networks active during wood decay towards decreased reliance on enzymatic machinery, and therefore nitrogen-intensive decay components. This shift was likely accompanied with adaptation to a narrow tree line habitat and switch to a pioneer decomposer strategy, both requiring rapid colonization of a nitrogen-limited substrate. Among substrate specialists with narrow niches, we also found evidence for pathways facilitating reversal to generalism, highlighting how evolution may move along different axes of niche space.

生态位宽度和促进其进化的机制是理解对不断变化的环境的适应、通才和专科谱系的持久性以及新物种的形成的基础。木质基质是结构复杂的资源，由具有专门腐烂机制的生物体利用。木材腐烂真菌是研究生态位宽度演化的理想模型系统，因为它们的宿主范围和基质的首选腐烂阶段差异很大。为了剖析入侵性褐腐真菌Serpula lacrymans生态位专门化的遗传基础，我们使用系统发育和转录组数据的表型分析和综合分析，通过一系列从专业到通才的腐烂策略，将该物种与 Serpulaceae 的野生近缘种进行比较。我们的研究结果表明，特殊物种在木材腐烂过程中重新连接了活跃的调节网络，减少了对酶促机制的依赖，从而减少了对氮密集型腐烂成分的依赖。这种转变可能伴随着对狭窄林线栖息地的适应和向先驱分解者策略的转变，两者都需要在氮限制基质上快速定殖。在具有狭窄生态位的基质专家中，我们还发现了促进普遍主义逆转的途径的证据，强调了进化如何沿着生态位空间的不同轴移动。