Understanding how ecological traits have changed over evolutionary time is a fundamental question in biology. Specifically, the extent to which more closely related organisms share similar ecological preferences due to phylogenetic conservation - or if they are forced apart by competition - is still debated. Here, we explored the co-occurrence patterns of freshwater cyanobacteria at the sub-genus level to investigate whether more closely related taxa share more similar niches and to what extent these niches were defined by abiotic or biotic variables. We used deep 16S rRNA gene amplicon sequencing and measured several abiotic environmental parameters (nutrients, temperature, etc.) in water samples collected over time and space in Furnas Reservoir, Brazil. We found that relatively more closely related Synechococcus (in the continuous range of 93%-100% nucleotide identity in 16S) had an increased tendency to co-occur with one another (i.e. had similar realized niches). This tendency could not be easily explained by shared preferences for measured abiotic niche dimensions. Thus, commonly measured abiotic parameters might not be sufficient to characterize, nor to predict community assembly or dynamics. Rather, co-occurrence between Synechococcus and the surrounding community (whether or not they represent true biological interactions) may be a more sensitive measure of realized niches. Overall, our results suggest that realized niches are phylogenetically conserved, at least at the sub-genus level and at the resolution of the 16S marker. Determining how these results generalize to other genera and at finer genetic resolution merits further investigation.

中文翻译：

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淡水Synechococcus中已实现的生态位的演变。

了解生态特征在进化过程中是如何变化的是生物学中的一个基本问题。特别是，由于系统发育的保守性，或者由于竞争而被迫分离开来，更密切相关的生物在多大程度上共享相似的生态偏好，仍然存在争议。在这里，我们探索了亚属水平的淡水蓝细菌的共生模式，以研究更密切相关的类群是否共享更多相似的生态位，以及这些生态位在多大程度上由非生物或生物变量定义。我们使用深16S rRNA基因扩增子测序，并测量了巴西Furnas水库随时间和空间收集的水样本中的一些非生物环境参数（营养物，温度等）。我们发现相对更紧密相关的Syechococcus（在16S中93％-100％核苷酸同一性的连续范围内）彼此共存的趋势增加（即具有相似的已实现生态位）。对于测量的非生物生态位尺寸的共同偏好无法轻易解释这种趋势。因此，通常测量的非生物参数可能不足以表征或预测社区的集会或动态。相反，Syechococcus和周围社区之间的共现（无论它们是否代表真正的生物相互作用）可能是已实现的生态位的更敏感度量。总体而言，我们的结果表明，已实现的生态位至少在亚属水平和16S标记的分辨率上在系统发育上是保守的。