A nonadaptive explanation for macroevolutionary patterns in the evolution of complex multicellularity.
A nonadaptive 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：
10.1073/pnas.2319840121
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发表时间：
2024
影响因子：
11.1
通讯作者：
Ratcliff,WilliamC
中科院分区：
文献类型：
--
作者：
Bingham,EmmaP;Ratcliff,WilliamC
“复杂多细胞”，通常被定义为具有许多特殊细胞类型的大型生物，在真核生物中已经独立进化了五次，但从未在原核生物中进化过。人们提出了许多假说来解释这一现象，其中大多数假说认为真核生物进化出的关键特征(如动态细胞骨架、基因调控的替代机制或亚细胞室)是复杂多细胞进化的必要前提。在这里，我们对这一广泛的宏观进化模式提出了一个替代的、非适应性的假设。通过将细胞分成世代之间具有有限遗传瓶颈的群体，多细胞进化大大减少了细胞群体的有效种群规模(Ne)，增加了遗传漂移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截然不同：真核生物往往经历基因组扩张，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，我们假设这些特殊的谱系特有的进化动态在整个生命树上复杂的多细胞的长期发散进化中发挥了基础性作用。
“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.