Mathematical modeling of evolution of horizontally transferred genes
Mathematical modeling of evolution of horizontally transferred genes
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DOI：
10.1093/molbev/msi167
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发表时间：
2005-08-01
影响因子：
10.7
通讯作者：
Koonin, EV
中科院分区：
文献类型：
--
作者：
Novozhilov, AS;Karev, GP;Koonin, EV
描述了微生物种群中水平转移基因进化的随机出生和死亡模型。该模型是由贝格和Kurland描述的随机模型的推广，并且包括五个参数：突变失活率、选择系数、入侵率（即，新序列从受体群体外部到达的速率）、群体内水平传播（“感染”）速率和群体大小。贝格和Kurland的模型包括四个参数，即突变失活、选择系数、群体大小和“感染”。然而，在对结果的解释中忽略了“感染”的影响，总体结论是，水平获得的序列只有在它们赋予受体实质性的选择优势时才能在群体中固定，因此受到强烈的正选择。本模型在不同领域的参数值的分析表明，只要人口内的水平传播率是可比的突变失活率，甚至有一个低的入侵率，水平获得的序列可以固定在人口中，或至少持续很长一段时间，在人口中的一个相当大的比例的个人，即使他们是中性或轻微有害的。现有的生物学数据有力地表明，至少对某些原核生物物种和环境来说，种群内甚至种群间的基因流动是现实的。因此，我们的建模结果与水平基因转移在原核生物进化中的关键作用的概念是兼容的。
describe a stochastic birth-and-death model of evolution of horizontally transferred genes in microbial populations. The model is a generalization of the stochastic model described by Berg and Kurland and includes five parameters: the rate of mutational inactivation, selection coefficient, invasion rate (i.e., rate of arrival of a novel sequence from outside of the recipient population), within-population horizontal transmission ("infection") rate, and population size. The model of Berg and Kurland included four parameters, namely, mutational inactivation, selection coefficient, population size, and "infection." However, the effect of "infection" was disregarded in the interpretation of the results, and the overall conclusion was that horizontally acquired sequences can be fixed in a population only when they confer a substantial selective advantage onto the recipient and therefore are subject to strong positive selection. Analysis of the present model in different domains of parameter values shows that, as long as the rate of within-population horizontal transmission is comparable to the mutational inactivation rate and there is even a low rate of invasion, horizontally acquired sequences can be fixed in the population or at least persist for a long time in a substantial fraction of individuals in the population even when they are neutral or slightly deleterious. The available biological data strongly suggest that intense within-population and even between-poputations gene flows are realistic for at least some prokaryotic species and environments. Therefore, our modeling results are compatible with the notion of a pivotal role of horizontal gene transfer in the evolution of prokaryotes.