Toward the Darwinian transition: Switching between distributed and speciated states in a simple model of early life
Toward the Darwinian transition: Switching between distributed and speciated states in a simple model of early life
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DOI：
10.1103/physreve.92.052909
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发表时间：
2015-11-13
影响因子：
2.4
通讯作者：
Timme, Marc
中科院分区：
文献类型：
--
作者：
Arnoldt, Hinrich;Strogatz, Steven H.;Timme, Marc
据推测，在最后一个普遍的共同祖先出现之前的时代，地球上的生命基本上是集体的。古代生命形式通过大规模水平基因转移（HGT）自由地共享其遗传物质。然而，在某一时刻，生活向个性和垂直下降的现代时代过渡。在这里，我们提出了一个最小的随机过程模型，可能有助于这种假设的“达尔文过渡”。该模型表明，HGT主导的动态可能被选择驱动的过程间歇性中断，在此过程中，基因型变得更适合，并降低了它们对HGT的倾向。种群动态中具有三点（超网络）相互作用的随机切换可能破坏了hgt主导的集体状态，并从根本上促成了垂直下降和早期进化中第一个定义明确的物种的出现。对涵盖进化过程关键特征（如选择、突变、漂变和HGT）的随机模型动力学的系统非线性分析支持这一观点。因此，我们的发现为早期的集体进化提供了一个可行的方向，可能使个体和垂直达尔文进化的开始成为可能。
It has been hypothesized that in the era just before the last universal common ancestor emerged, life on earth was fundamentally collective. Ancient life forms shared their genetic material freely through massive horizontal gene transfer (HGT). At a certain point, however, life made a transition to the modern era of individuality and vertical descent. Here we present a minimal model for stochastic processes potentially contributing to this hypothesized "Darwinian transition." The model suggests that HGT-dominated dynamics may have been intermittently interrupted by selection-driven processes during which genotypes became fitter and decreased their inclination toward HGT. Stochastic switching in the population dynamics with three-point (hypernetwork) interactions may have destabilized the HGT-dominated collective state and essentially contributed to the emergence of vertical descent and the first well-defined species in early evolution. A systematic nonlinear analysis of the stochastic model dynamics covering key features of evolutionary processes (such as selection, mutation, drift and HGT) supports this view. Our findings thus suggest a viable direction out of early collective evolution, potentially enabling the start of individuality and vertical Darwinian evolution.