Data from: Genetic and genomic evidence of niche partitioning and adaptive radiation in mountain pine beetle fungal symbionts

AbstractBark beetles form multipartite symbiotic associations with blue stain fungi (Ophiostomatales, Ascomycota). These fungal symbionts play an important role during the beetle's life cycle by providing nutritional supplementation, overcoming tree defences and modifying host tissues to favour brood development. The maintenance of stable multipartite symbioses with seemingly less competitive symbionts in similar habitats is of fundamental interest to ecology and evolution. We tested the hypothesis that the coexistence of three fungal species associated with the mountain pine beetle is the result of niche partitioning and adaptive radiation using SNP genotyping coupled with genotype–environment association analysis and phenotypic characterization of growth rate under different temperatures. We found that genetic variation and population structure within each species is best explained by distinct spatial and environmental variables. We observed both common (temperature seasonality and the host species) and distinct (drought, cold stress, precipitation) environmental and spatial factors that shaped the genomes of these fungi resulting in contrasting outcomes. Phenotypic intraspecific variations in Grosmannia clavigera and Leptographium longiclavatum, together with high heritability, suggest potential for adaptive selection in these species. By contrast, Ophiostoma montium displayed narrower intraspecific variation but greater tolerance to extreme high temperatures. Our study highlights unique phenotypic and genotypic characteristics in these symbionts that are consistent with our hypothesis. By maintaining this multipartite relationship, the bark beetles have a greater likelihood of obtaining the benefits afforded by the fungi and reduce the risk of being left aposymbiotic. Complementarity among species could facilitate colonization of new habitats and survival under adverse conditions., Usage notesData fileExcel workbook containing the SNP data, environmental data and growth data for G. clavigera, L. leptographium and O. montium.BSF_dryad.xls摘要：小蠹虫与蓝变真菌（长喙壳目，子囊菌门）形成多伙伴共生体系。此类真菌共生体在小蠹虫的生命周期中扮演关键角色：可为其提供营养补给、协助突破寄主树木的防御系统，并修饰寄主组织以优化子代发育。在相似生境中维持与看似竞争力较弱的共生体构建稳定多伙伴共生关系，是生态学与进化生物学领域的核心研究命题。本研究针对山松小蠹虫关联的3种真菌物种的共存现象验证假说：该共存现象源于生态位分化与适应性辐射。研究采用单核苷酸多态性（Single Nucleotide Polymorphism, SNP）基因分型技术，结合基因型-环境关联分析，以及不同温度梯度下的生长速率表型表征方法开展实验。结果表明，各物种内部的遗传变异与种群结构，可通过独特的空间与环境变量得到最佳解释。研究同时观测到两类塑造这些真菌基因组的因子：一类为共有因子（温度季节性与寄主物种），另一类为差异化因子（干旱、冷胁迫与降水），最终导致了迥异的演化结果。对克拉维奥氏长喙壳（Grosmannia clavigera）与长爪细帚霉（Leptographium longiclavatum）的表型种内变异分析显示，其变异具有较高的遗传力，提示这两个物种存在适应性选择的潜力。相较而言，山生帚形孢（Ophiostoma montium）的种内变异范围较窄，但对极端高温的耐受性更强。本研究揭示了这些共生体独特的表型与基因型特征，与本研究提出的假说相符。通过维持这种多伙伴共生关系，小蠹虫获取真菌提供的益处的概率显著提升，同时降低了自身处于无共生体状态的风险。物种间的功能互补可助力其开拓新生境，并在逆境条件下维持存活。 使用说明：本数据文件为Excel工作簿，包含克拉维奥氏长喙壳、长爪细帚霉与山生帚形孢的SNP数据、环境数据及生长数据。文件名为BSF_dryad.xls