In environments where females mate multiply, males should adjust their behaviour and physiology in response to the perceived level of sperm competition to maximize their fitness. Evidence of such plasticity has been found in several laboratory and field studies, but little is known about the cues stimulating these 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 males (i.e. food patches or potential mates), which in turn affects local density. However, explicit links between resource distribution, male encounter rates and shifts in behaviour related to sperm competition have not been demonstrated. We found that when group size of Drosophila melanogaster males was held constant, a small decrease in the distance between patches of food resources had striking effects on male behaviour. Compared to those from dispersed resources, males on clustered resources had a significantly reduced intermale distance (and hence encounter rate) and subsequently a longer noncompetitive copulation duration, previously shown to be a reliable indicator of male perception of sperm competition risk. The aggregation of resources, operating via increased encounter rate, can stimulate shifts in behaviour affecting male sperm competition performance. Given that the spatial distribution of resources is typically variable in natural populations (and often unpredictable), selection is likely to favour the evolution of plasticity in sexual behaviour where resource aggregation increases the probability of sperm competition.

中文翻译：

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空间集群资源增加了黑腹果蝇的雄性聚集和交配时间

在雌性交配繁殖的环境中，雄性应根据感知到的精子竞争水平调整其行为和生理机能，以最大限度地提高其健康水平。在一些实验室和实地研究中已经发现了这种可塑性的证据，但对于在自然种群中刺激这些反应的线索知之甚少。雄性评估精子竞争风险的一种方法是通过与同种雄性的相遇率。这种遭遇率可能是由雄性所需资源的空间分布（即食物斑块或潜在配偶）驱动的，这反过来又会影响当地的密度。然而，资源分布、男性遭遇率和与精子竞争相关的行为转变之间的明确联系尚未得到证实。我们发现，当黑腹果蝇雄性的群体规模保持不变时，食物资源斑块之间距离的小幅减少会对雄性行为产生显着影响。与来自分散资源的雄性相比，聚集资源上的雄性雄性之间的距离显着减少（因此相遇率），随后非竞争性交配持续时间更长，以前被证明是雄性对精子竞争风险感知的可靠指标。资源的聚集，通过增加相遇率来运作，可以刺激影响男性精子竞争表现的行为转变。鉴于资源的空间分布在自然种群中通常是可变的（并且通常是不可预测的），