A non-adaptive explanation for macroevolutionary patterns in the evolution of complex multicellularity.
A non-adaptive explanation for macroevolutionary patterns in the evolution of complex multicellularity.
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对复杂多细胞进化中宏观进化模式的非适应性解释。
DOI：
10.1101/2023.11.11.566713
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Ratcliff,WilliamC
中科院分区：
文献类型：
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作者：
Bingham,EmmaP;Ratcliff,WilliamC
“复杂多细胞性”，传统上定义为具有许多特化细胞类型的大型生物，在真核生物中独立进化了五次，但从未在原核生物中进化过。已经提出了许多假设来解释这一现象，其中大多数假设认为真核生物进化了关键性状（例如，动态细胞骨架、基因调控的替代机制或亚细胞区室），这是复杂多细胞进化的必要先决条件。在这里，我们提出了一个替代的，非适应性的假设，这种广泛的宏观进化模式。通过将细胞分组，在世代之间具有有限的遗传瓶颈，多细胞的进化大大减少了细胞群体的有效群体大小（Ne），增加了遗传漂变在进化变化中的作用。虽然原核生物和真核生物都经历了这种现象，但它们对漂移的反应相反：真核生物倾向于进行基因组扩增，为随后的多细胞创新提供额外的原始遗传物质，而原核生物通常面临基因组侵蚀。综上所述，我们假设，这些特质的谱系特定的进化动力学在整个生命之树的复杂多细胞的长期分歧进化中发挥了根本性的作用。
“Complex multicellularity,” conventionally defined as large organisms with many specialized cell types, has evolved five times independently in eukaryotes, but never within prokaryotes. A number of hypotheses have been proposed to explain this phenomenon, most of which posit that eukaryotes evolved key traits (e.g., dynamic cytoskeletons, alternative mechanisms of gene regulation, or subcellular compartments) which were a necessary prerequisite for the evolution of complex multicellularity. Here, we propose an alternative, nonadaptive hypothesis for this broad macroevolutionary pattern. By binning cells into groups with finite genetic bottlenecks between generations, the evolution of multicellularity greatly reduces the effective population size (Ne) of cellular populations, increasing the role of genetic drift in evolutionary change. While both prokaryotes and eukaryotes experience this phenomenon, they have opposite responses to drift: eukaryotes tend to undergo genomic expansion, providing additional raw genetic material for subsequent multicellular innovation, while prokaryotes generally face genomic erosion. Taken together, we hypothesize that these idiosyncratic lineage-specific evolutionary dynamics play a fundamental role in the long-term divergent evolution of complex multicellularity across the tree of life.