Data from: Patterns of specificity of the pathogen Escovopsis across the fungus-growing ant symbiosis

Parasites evolve within complex abiotic and biotic environments. Because of this, it is often challenging to ascertain how evolutionary and ecological processes together affect parasite specialization. Here, we use the fungus-growing ant system, which consists of ancient, likely coevolved, complex communities, to explore the ecological and evolutionary forces shaping host-parasite specificity. We use a comparative phylogenetic framework to determine if patterns of specificity between the fungal parasite Escovopsis and its host fungi at fine phylogenetic scales reflect patterns of specificity at broader phylogenetic levels. In other words, we ask whether parasite specificity across broad host phylogenetic relationships is maintained by specificity towards more closely related hosts. We couple this exploration with manipulations of the community context within which host-parasite interactions are taking place to evaluate how community complexity alters parasite specificity. Regardless of host community complexity, parasites displayed a consistent pattern of specialization on native hosts, i.e. those that they are found attacking in nature, with the potential for occasional switching to hosts distantly related to their native hosts. These results suggest that, even within a complex community context, pairwise host and parasite adaptation and coadaptation can be the primary drivers of the evolution and maintenance of parasite specificity.

寄生虫在复杂的非生物与生物环境中演化。正因如此，厘清演化与生态过程如何共同影响寄生生物特化往往极具挑战。本研究以切叶蚁（fungus-growing ant）系统为研究对象，该系统包含古老且大概率存在协同演化的复杂群落，以此探究塑造宿主-寄生生物特异性的生态与演化力量。我们采用比较系统发育分析框架，旨在明确：在精细系统发育尺度下，真菌寄生生物埃斯科沃氏菌（Escovopsis）与其宿主真菌间的特异性模式，是否与更宽泛系统发育尺度下的特异性模式相一致。换言之，我们旨在探究：寄生生物在宽泛宿主系统发育关系中的特异性，是否由其对亲缘关系更近宿主的特异性所维持。我们将该探究与宿主-寄生生物相互作用所处群落背景的操控实验相结合，以此评估群落复杂性如何改变寄生生物的特异性。无论宿主群落复杂性如何，寄生生物均表现出对本地宿主（即野外环境中其实际侵染的宿主）的特化模式，仅存在偶尔转换至与本地宿主亲缘关系较远宿主的可能性。上述结果表明，即便处于复杂群落背景中，宿主与寄生生物间的成对适应性及协同适应性，仍可成为寄生生物特异性演化与维持的核心驱动因素。