Coexistence and error propagation in pre-biotic vesicle models:: A group selection approach
Coexistence and error propagation in pre-biotic vesicle models:: A group selection approach
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DOI：
10.1016/j.jtbi.2005.08.039
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发表时间：
2006-03-21
影响因子：
2
通讯作者：
Szathmáry, E
中科院分区：
文献类型：
--
作者：
Fontanari, JF;Santos, M;Szathmáry, E
将相互独立的竞争模板进行区室化被广泛认为是复杂生物进化的必要步骤。然而，限制在有限大小的孤立囊泡中的模板保存信息面临着比自由模板更困难的障碍：与突变压力相关联的随机漂移消除了任何不能完美复制的模板，无论错误概率有多小。此外，单独的漂移会阻碍不同模板在同一区室中的共存。在这里，我们调查的条件组选择占上风的漂移和突变，从而保证不同的模板在一个囊泡的维护和共存。通过依赖于模板组成的囊泡存活概率来实现组选择。通过考虑无限数量囊泡的极限情况。每一个携带有限数量的模板，我们能够推导出一组递归方程的频率与不同的模板组成的囊泡。这些递归的数值迭代允许囊泡群体的稳定状态的准确表征的准种囊泡，从而揭示了模板共存的突变和组选择强度的值是可能的。在模型的主要假设-一个固定的，有限的或无限的，囊泡的数量-我们发现没有根本的障碍，一个囊泡内具有相同的复制速率的任意数量的模板类型的共存，当然除了囊泡容量。即使在不存在不同模板的基因组内竞争的情况下，囊泡选择形式的群体选择对于区室化原始遗传系统也是必须的。(C)2005 Elsevier Ltd.保留所有权利。
Compartmentalization of unlinked, competing templates is widely accepted as a necessary step towards the evolution of complex organisms. However, preservation of information by templates confined to isolated vesicles of finite size faces much harder obstacles than by free templates: random drift allied to mutation pressure wipe Out any template that does not replicate perfectly, no matter how small the error probability might be. In addition, drift alone hinders the coexistence of distinct templates in a same compartment. Here, we investigate the conditions for group selection to prevail over drift and mutation and hence to guarantee the maintenance and coexistence of distinct templates in a vesicle. Group selection is implemented through a vesicle Survival probability that depends on the template composition. By considering the limit case of an infinite number of vesicles. each one carrying a finite number of templates, we were able to derive a set of recursion equations for the frequencies of vesicles with different template compositions. Numerical iteration of these recursions allows the exact characterization of the steady state of the vesicle population-a quasispecies of vesicles-thus revealing the values of the mutation and group selection intensities for which template coexistence is possible. Within the main assumption of the model-a fixed, finite or infinite, number of vesicles-we find no fundamental impediment to the coexistence of an arbitrary number of template types with the same replication rate inside a vesicle, except of course for the vesicle capacity. Group selection in the form of vesicle selection is a must for compartmentalized primordial genetic systems even in the absence of intra-genomic competition of different templates. (C) 2005 Elsevier Ltd. All rights reserved.