Department of Biology, Plant-Microbe Interactions, Utrecht University, Utrecht, CH, 3584, The Netherlands.
Institut für Biologie, Freie Universität Berlin, Berlin, D-14195, Germany.
Evolution. 2021 May;75(5):1218-1229. doi: 10.1111/evo.14202. Epub 2021 Mar 8.
There is a growing awareness that traits do not evolve individually but rather are organized as modular networks of covarying traits. Although the importance of multi-trait correlation has been linked to the ability to evolve in response to new environmental conditions, the evolvability of the network itself has to date rarely been assessed experimentally. By following the evolutionary dynamics of a model bacterium adapting to plant roots, we demonstrate that the whole structure of the trait correlation network is highly dynamic. We experimentally evolved Pseudomonas protegens, a common rhizosphere dweller, on the roots of Arabidopsis thaliana. We collected bacteria at regular intervals and determined a range of traits linked to growth, stress resistance, and biotic interactions. We observed a rapid disintegration of the original trait correlation network. Ancestral populations showed a modular network, with the traits linked to resource use and stress resistance forming two largely independent modules. This network rapidly was restructured during adaptation, with a loss of the stress resistance module and the appearance of new modules out of previously disconnected traits. These results show that evolutionary dynamics can involve a deep restructuring of phenotypic trait organization, pointing to the emergence of novel life history strategies not represented in the ancestral phenotype.
人们越来越意识到，特征不是单独进化的，而是作为具有协变特征的模块化网络组织起来的。虽然多特征相关性的重要性与适应新环境条件的能力有关，但迄今为止，很少有实验评估网络本身的可进化性。通过跟踪适应植物根系的模式细菌的进化动态，我们证明了特征相关网络的整体结构具有高度动态性。我们在拟南芥的根上对常见的根际居民假单胞菌进行了实验进化。我们定期收集细菌并确定了一系列与生长、抗逆性和生物相互作用相关的特征。我们观察到原始特征相关网络迅速瓦解。祖先种群表现出模块化网络，与资源利用和抗逆性相关的特征形成两个基本独立的模块。在适应过程中，网络迅速重构，抗逆性模块丢失，先前不相关的特征出现新模块。这些结果表明，进化动态可能涉及表型特征组织的深刻重构，表明出现了在祖先表型中没有表现出来的新的生活史策略。
