Interfering waves of adaptation promote spatial mixing.
Interfering waves of adaptation promote spatial mixing.
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DOI：
10.1534/genetics.111.130112
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发表时间：
2011-11
期刊：
影响因子：
3.3
通讯作者：
Hallatschek O
中科院分区：
文献类型：
--
作者：
Martens EA;Hallatschek O
无性适应的一个根本问题是，有益的替代并不能有效地在大种群中积累：有益的突变往往会灭绝，因为它们会在固定过程中相互竞争。有人认为，这种克隆干扰可能导致了混合良好的种群中性别和重组的进化。在这里，我们研究了克隆干扰及其缓解机制，在一个空间结构的种群进化模型中，具有统一的选择压力。有空间结构的克隆干扰比没有空间结构的要普遍得多，这是因为有益突变在空间中以波状缓慢传播。我们发现，当线性栖息地大小超过特征干扰长度时，无性动物的适应速度就饱和了，干扰长度越短，迁移量越小，突变率越大。线性生境和平面生境的极限速度分别与μ1/2和μ1/3成正比，突变供给μ是突变率和局部种群密度的乘积。这种规模和速度限制的存在应该接受实验测试，因为它们远远低于混合良好的种群的预测适应速度(该规模是种群规模的对数)。最后，我们证明了不仅重组，而且远距离迁移也是在结构化种群中放松克隆竞争的一种高效机制。我们对干扰长度的保守估计预测了微生物群体和生物膜中普遍存在的克隆干扰，因此克隆竞争应该是这些环境中遗传和空间混合的强大驱动因素。
A fundamental problem of asexual adaptation is that beneficial substitutions are not efficiently accumulated in large populations: Beneficial mutations often go extinct because they compete with one another in going to fixation. It has been argued that such clonal interference may have led to the evolution of sex and recombination in well-mixed populations. Here, we study clonal interference, and mechanisms of its mitigation, in an evolutionary model of spatially structured populations with uniform selection pressure. Clonal interference is much more prevalent with spatial structure than without, due to the slow wave-like spread of beneficial mutations through space. We find that the adaptation speed of asexuals saturates when the linear habitat size exceeds a characteristic interference length, which becomes shorter with smaller migration and larger mutation rate. The limiting speed is proportional to μ1/2 and μ1/3 in linear and planar habitats, respectively, where the mutational supply μ is the product of mutation rate and local population density. This scaling and the existence of a speed limit should be amenable to experimental tests as they fall far below predicted adaptation speeds for well-mixed populations (that scale as the logarithm of population size). Finally, we show that not only recombination, but also long-range migration is a highly efficient mechanism of relaxing clonal competition in structured populations. Our conservative estimates of the interference length predict prevalent clonal interference in microbial colonies and biofilms, so clonal competition should be a strong driver of both genetic and spatial mixing in those contexts.
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影响因子：
8.6
作者：
KARDAR, M;PARISI, G;ZHANG, YC
通讯作者：
ZHANG, YC
影响因子：
8.8
作者：
Habets, Michelle G. J. L.;Rozen, Daniel E.;de Visser, J. Arjan G. M.
通讯作者：
de Visser, J. Arjan G. M.
影响因子：
56.9
作者：
Elena, SF;Cooper, VS;Lenski, RE
通讯作者：
Lenski, RE
DOI：
10.1073/pnas.0505903103
发表时间：
2006-01-17
影响因子：
11.1
作者：
Greaves, LC;Preston, SL;McDonald, SAC
通讯作者：
McDonald, SAC
影响因子：
56.9
作者：
de Visser, JAGM;Zeyl, CW;Lenski, RE
通讯作者：
Lenski, RE