DENSITY DEPENDENCE AND COOPERATION: THEORY AND A TEST WITH BACTERIA
DENSITY DEPENDENCE AND COOPERATION: THEORY AND A TEST WITH BACTERIA
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DOI：
10.1111/j.1558-5646.2009.00723.x
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发表时间：
2009-09-01
期刊：
影响因子：
3.3
通讯作者：
Griffin, Ashleigh S.
中科院分区：
文献类型：
--
作者：
Ross-Gillespie, Adin;Gardner, Andy;Griffin, Ashleigh S.
尽管合作系统可以持续存在的性质，尽管潜在的剥削由noncooperators，它是经常观察到的人口统计学的小变化可以倾斜的平衡选择力或反对合作。在这里，我们考虑种群密度在微生物合作背景下的作用。首先，我们解释了最近的研究中相互矛盾的结果，从理论上证明：（1）对于公共产品合作，较高的密度是相对不利的合作;（2）相反，对于自我约束型合作，较高的密度可以是有利的或不利的合作，这取决于系统的细节。然后，我们测试我们的预测公共产品合作使用菌株的致病性细菌铜绿假单胞菌，产生可变水平的公共产品铁清除铁载体分子。正如预测的那样，我们发现作弊者（生产不足者）的相对适应性在人口密度较高时最大。此外，假设的理论，我们表明，这是因为骗子能够更好地利用其他细胞的合作铁载体生产时，他们是物理上更接近他们。
Although cooperative systems can persist in nature despite the potential for exploitation by noncooperators, it is often observed that small changes in population demography can tip the balance of selective forces for or against cooperation. Here we consider the role of population density in the context of microbial cooperation. First, we account for conflicting results from recent studies by demonstrating theoretically that: (1) for public goods cooperation, higher densities are relatively unfavorable for cooperation; (2) in contrast, for self-restraint-type cooperation, higher densities can be either favorable or unfavorable for cooperation, depending on the details of the system. We then test our predictions concerning public goods cooperation using strains of the pathogenic bacterium Pseudomonas aeruginosa that produce variable levels of a public good-iron-scavenging siderophore molecules. As predicted, we found that the relative fitness of cheats (under-producers) was greatest at higher population densities. Furthermore, as assumed by theory, we show that this occurs because cheats are better able to exploit the cooperative siderophore production of other cells when they are physically closer to them.