In environments where females mate multiply, males should adjust their behaviour and physiology in response to the prevailing perceived level of sperm competition. This expectation is well supported by both laboratory and field studies, but we don’t yet know what mechanisms facilitate these plastic responses in natural populations. One way in which males appear to assess sperm competition risk is through encounter rates with conspecific males. Such encounter rates may be driven by the spatial distribution of resources required by male. However, explicit links between resource distribution, male encounter rate, and shifts in behaviour related to sperm competition have not been demonstrated. Here we show that a small increase in the distance of patches of food resources in the laboratory: (a) approximately halves the mean distances between pairs of males; and (b) is associated with an increase in subsequent copulation duration – previously shown to be a reliable indicator of male perception of sperm competition risk – by more than two minutes. Aggregation of resources, operating via increased encounter rate, is a mechanism that can stimulate plastic male sperm competition responses. Because spatial distribution of resources, including those exploited by Drosophila, is variable in nature, this may explain one way in which sperm competition-related plasticity is influenced in wild-living males.

中文翻译：

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空间聚集的资源增加了果蝇的聚集和交配持续时间

在雌性交配的环境中，雄性应根据普遍认为的精子竞争水平来调整其行为和生理。实验室和实地研究都很好地支持了这一期望，但是我们还不知道什么机制可以促进自然种群中的这些可塑性反应。雄性评估精子竞争风险的一种方法是通过与同种雄性的遭遇率。这种遭遇率可能由男性所需资源的空间分布所驱动。但是，尚未证明资源分配，男性遭遇率以及与精子竞争有关的行为转变之间的明确联系。在这里，我们表明实验室中食物资源补丁的距离略有增加：（a）大约将成对的男性之间的平均距离减半；（b）与随后的交配持续时间增加-超过两分钟有关-先前的交配持续时间被证明是男性对精子竞争风险感知的可靠指标。通过增加遭遇率进行操作的资源聚集是一种可以刺激男性精子竞争反应的机制。因为资源的空间分布，包括那些被利用的资源果蝇本质上是可变的，这可以解释一种影响野生动物雄性中与精子竞争相关的可塑性的一种方式。