Genetic and phenotypic variation among individuals increases population resilience to external disturbances and enables quicker adaptation to changing environments. Since the predominant phase in the fungal lifecycle occurs belowground or within substrates, it is difficult to assess the level of variation in functional traits occurring within species in natural environments. In this study, we investigated phenotypic variation in the wood-decay fungus Phellopilus nigrolimitatus and related this to genet size, measured as vegetative compatibility groups (VCGs). Out of 321 wood samples and sporocarps collected on six logs of Picea abies, we isolated 230 dikaryotic isolates that were grouped into 53 VCGs based on culturing experiments. The number of VCGs per log varied from six to twelve, with large variation in sizes; the smallest VCG was derived from a single wood sample, while the largest was isolated across 31 wood samples stretching over 15 m. The size of the VCGs was positively correlated with the area of the spore-producing layer of the sporocarps, implying that larger genets produce more spores. Additionally, the phenotypic variation among isolates of P. nigrolimitatus was high, both in terms of growth morphology and coloration, and consistent with the delimitation of isolates into VCGs. Isolates could to a large extent be correctly assigned to the VCGs a priori based purely on culture phenotype. This study reveals that extensive phenotypic variation can be observed between fungal genets at very fine spatial scale, and calls for more studies looking at intraspecific phenotypic variation, in line with assessing genetic diversity in fungi.

个体之间的遗传和表型变异增加了种群对外部干扰的适应力，并使人们能够更快地适应不断变化的环境。由于真菌生命周期的主要阶段发生在地下或基质内，因此很难评估自然环境中物种内部发生的功能性状变化水平。在这项研究中，我们调查了木腐真菌黄萎病菌（Phellopilus nigrolimitatus）的表型变异，并将其与种系大小相关，以植物相容性组（VCG）衡量。在六个云杉云杉原木上采集的321份木材样品和子果皮中，我们根据培养实验分离了230个双核分离株，这些分离株分为53个VCG。每个对数的VCG数量从六个到十二个不等，大小差异很大。最小的VCG来自单个木材样品，而最大的VCG是跨31个长度超过15 m的木材样品分离出来的。VCG的大小与子果皮孢子产生层的面积成正相关，这意味着更大的种系产生更多的孢子。另外，就生长形态和颜色而言，黑斑假单胞菌 分离株之间的表型变异很高，并且与分离株向VCG的界定一致。隔离区可以在很大程度上事先正确地分配给VCG纯粹基于文化表型。这项研究表明，可以在非常精细的空间尺度上观察到真菌种系之间广泛的表型变异，并呼吁开展更多的研究来研究种内表型变异，以评估真菌的遗传多样性。