Durão Paulo, Amicone Massimo, Perfeito Lília, Gordo Isabel
Instituto Gulbenkian de Ciência Oeiras Portugal.
Present address: Laboratório de Instrumentação e Física Experimental de Partículas Lisboa Portugal.
Ecol Evol. 2021 Oct 9;11(21):15085-15097. doi: 10.1002/ece3.8191. eCollection 2021 Nov.
Experimental evolution studies with microorganisms such as bacteria and yeast have been an increasingly important and powerful tool to draw long-term inferences of how microbes interact. However, while several strains of the same species often exist in natural environments, many ecology and evolution studies in microbes are typically performed with isogenic populations of bacteria or yeast. In the present study, we firstly perform a genotypic and phenotypic characterization of two laboratory and eight natural strains of the yeast . We then propagated, in a rich resource environment, yeast communities of 2, 3, 4, and 5 strains for hundreds of generations and asked which fitness-related phenotypes-maximum growth rate or relative competitive fitness-would better predict the outcome of a focal strain during the propagations. While the strain's growth rates would wrongly predict long-term coexistence, pairwise competitive fitness with a focal strain qualitatively predicted the success or extinction of the focal strain by a simple multigenotype population genetics model, given the initial community composition. Interestingly, we have also measured the competitive fitness of the ancestral and evolved communities by the end of the experiment (≈370 generations) and observed frequent maladaptation to the abiotic environment in communities with more than three members. Overall, our results aid establishing pairwise competitive fitness as good qualitative measurement of long-term community composition but also reveal a complex adaptive scenario when trying to predict the evolutionary outcome of those communities.
对细菌和酵母等微生物进行的实验进化研究，已成为推断微生物如何相互作用的长期情况的一项日益重要且强大的工具。然而，尽管在自然环境中通常存在同一物种的多个菌株，但许多微生物的生态学和进化研究通常是使用细菌或酵母的同基因群体进行的。在本研究中，我们首先对两种实验室菌株和八种酵母自然菌株进行了基因型和表型特征分析。然后，我们在丰富资源环境中，将由2、3、4和5个菌株组成的酵母群落传代培养数百代，并探究哪种与适应性相关的表型——最大生长速率或相对竞争适应性——能更好地预测传代过程中焦点菌株的结果。虽然菌株的生长速率会错误地预测长期共存情况，但根据初始群落组成，通过一个简单的多基因型群体遗传学模型，焦点菌株与其他菌株的成对竞争适应性能够定性地预测焦点菌株的成功或灭绝。有趣的是，在实验结束时（约370代），我们还测量了原始群落和进化后群落的竞争适应性，并观察到在成员超过三个的群落中，频繁出现对非生物环境的适应不良情况。总体而言，我们的研究结果有助于将成对竞争适应性确立为长期群落组成的良好定性指标，但同时也揭示了在试图预测这些群落的进化结果时存在的复杂适应情况。
