Cooperation peaks at intermediate disturbance
Cooperation peaks at intermediate disturbance
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DOI：
10.1016/j.cub.2007.02.057
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发表时间：
2007-05-01
期刊：
影响因子：
9.2
通讯作者：
Gardner, Andy
中科院分区：
文献类型：
--
作者：
Brockhurst, Michael A.;Buckling, Angus;Gardner, Andy
解释合作是进化生物学的一个挑战[1，2]。令人惊讶的是，外部生态参数的作用仍然在很大程度上未被考虑。扰动[3，4]在自然界中广泛存在，并具有进化后果[5]。我们开发了一个数学模型，预测合作性状最容易在中间干扰演变。在不频繁的干扰下，合作会通过不断积累的作弊行为而破裂。更高的干扰率防止了这一点，因为由此产生的瓶颈增加了遗传结构（相关性[6-8]），促进了合作的亲缘选择。然而，如果人口密度仍然低于成功合作所需的水平，在非常频繁的干扰下，合作就无法持续。我们通过使用细菌荧光假单胞菌的协同生物膜形成来测试这些预测[9，10]。生物膜形成细菌的比例达到峰值，在中间的干扰，与模型预测的方式一致。在不频繁和中等干扰下，大多数细菌占据生物膜，但在不频繁干扰下，作弊的比例较高。在频繁的干扰下，许多细菌没有占据生物膜，这表明生物膜栖息在频繁干扰下与中等干扰下没有那么有益。考虑到自然界中干扰的普遍存在，
Explaining cooperation is a challenge for evolutionary biology [1, 2]. Surprisingly, the role of extrinsic ecological parameters remains largely unconsidered. Disturbances [3, 4] are widespread in nature and have evolutionary consequences [5]. We develop a mathematical model predicting that cooperative traits most readily evolve at intermediate disturbance. Under infrequent disturbance, cooperation breaks down through the accumulation of evolved cheats. Higher rates of disturbance prevent this because the resulting bottlenecks increase genetic structuring (relatedness [6-8]) promoting kin selection for cooperation. However, cooperation cannot be sustained under very frequent disturbance if population density remains below the level required for successful cooperation. We tested these predictions by using cooperative biofilm formation by the bacterium Pseudomonas fluorescens [9, 10]. The proportion of biofilm-forming bacteria peaked at intermediate disturbance, in a manner consistent with model predictions. Under infrequent and intermediate disturbance, most bacteria occupied the biofilm, but the proportion of cheats was higher under less frequent disturbance. Under frequent disturbance, many bacteria did not occupy the biofilm, suggesting that biofilm dwelling was not as beneficial under frequent versus intermediate disturbance. Given the ubiquity of disturbances in nature, these