Functional equivalence and evolutionary convergence in complex communities of microbial sponge symbionts
Functional equivalence and evolutionary convergence in complex communities of microbial sponge symbionts
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DOI：
10.1073/pnas.1203287109
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发表时间：
2012-07-03
影响因子：
11.1
通讯作者：
Thomas, Torsten
中科院分区：
文献类型：
--
作者：
Fan, Lu;Reynolds, David;Thomas, Torsten
微生物通常与真核生物形成共生关系，这些关系的复杂性可以从单一占主导地位的共生体到与数百种共生体的关联。在不同真核宿主中占据相同生态位的微生物共生体可能共享功能方面，并且已经报道了昆虫中简单共生体系统的趋同基因组进化。然而，对于复杂的共生群落，功能等效性有多普遍以及等效功能是否是通过进化趋同机制来执行的，在很大程度上尚不清楚。海绵代表了具有共同生理和生态特征的进化上不同的物种群体。它们还承载着复杂的微生物共生体群落，因此是测试系统发育不同宿主的复杂共生体群落中是否存在功能等价性和进化趋同性的理想模型。在这里，我们使用抽样设计来确定与六种海绵物种相关的微生物群落的系统发育和功能特征。我们确定了六个微生物组中的共同功能，证明了功能等效性的存在。这些核心功能与我们目前对海绵相关微生物的生物学和生态作用的理解一致，也提供了对共生体功能的深入了解。重要的是，每个海绵物种也通过类似的酶和生物合成途径提供核心功能。此外，参与水平基因转移的大量元素表明它们在共生体基因组进化中的关键作用。因此，我们的数据证明了复杂共生群落的进化趋同，并揭示了支持该过程的细节和机制。
Microorganisms often form symbiotic relationships with eukaryotes, and the complexity of these relationships can range from those with one single dominant symbiont to associations with hundreds of symbiont species. Microbial symbionts occupying equivalent niches in different eukaryotic hosts may share functional aspects, and convergent genome evolution has been reported for simple symbiont systems in insects. However, for complex symbiont communities, it is largely unknown how prevalent functional equivalence is and whether equivalent functions are conducted by evolutionarily convergent mechanisms. Sponges represent an evolutionarily divergent group of species with common physiological and ecological traits. They also host complex communities of microbial symbionts and thus are the ideal model to test whether functional equivalence and evolutionary convergence exist in complex symbiont communities across phylogenetically divergent hosts. Here we use a sampling design to determine the phylogenetic and functional profiles of microbial communities associated with six sponge species. We identify common functions in the six microbiomes, demonstrating the existence of functional equivalence. These core functions are consistent with our current understanding of the biological and ecological roles of sponge-associated microorganisms and also provide insight into symbiont functions. Importantly, core functions also are provided in each sponge species by analogous enzymes and biosynthetic pathways. Moreover, the abundance of elements involved in horizontal gene transfer suggests their key roles in the genomic evolution of symbionts. Our data thus demonstrate evolutionary convergence in complex symbiont communities and reveal the details and mechanisms that underpin the process.