Steiger Sandra, Franz Ragna, Eggert Anne-Katrin, Müller Josef K
Department of Evolutionary Biology and Ecology, Faculty of Biology, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany.
Proc Biol Sci. 2008 Aug 22;275(1645):1831-8. doi: 10.1098/rspb.2008.0375.
The ability to recognize individuals is an important aspect of social interactions, but it can also be useful to avoid repeated matings with the same individual. The Coolidge effect is the progressive decline in a male's propensity to mate with the same female combined with a heightened sexual interest in new females. Although males that recognize previous partners and show a preference for novel females should have a selective advantage as they can distribute sperm evenly among the females they encounter, there are few invertebrate examples of the Coolidge effect. Here we present evidence for this effect in the burying beetle Nicrophorus vespilloides and examine the mechanism underlying the discrimination between familiar and novel mates. Burying beetles feed and reproduce on vertebrate carcasses, where they regularly encounter conspecifics. Males showed greater sexual interest in novel females (virgin or mated) than in females they had inseminated before. The application of identical cuticular extracts allowed us to experimentally create females with similar odours, and male responses to such females demonstrated that they use female cuticular patterns for discrimination. The chemical analysis of the cuticular profile revealed greater inter-individual variation in female than in male cuticular patterns, which might be due to greater selection on females to signal their individual identity.
识别个体的能力是社会互动的一个重要方面，但它对于避免与同一个体重复交配也可能有用。柯立芝效应是指雄性与同一雌性交配的倾向逐渐下降，同时对新雌性的性兴趣增强。虽然能够识别先前伴侣并对新雌性表现出偏好的雄性应该具有选择优势，因为它们可以将精子均匀地分配给所遇到的雌性，但几乎没有无脊椎动物存在柯立芝效应的例子。在此，我们展示了埋葬虫Nicrophorus vespilloides中这种效应的证据，并研究了区分熟悉和陌生配偶背后的机制。埋葬虫在脊椎动物尸体上觅食和繁殖，在那里它们经常遇到同种个体。雄性对新雌性（处女或已交配）表现出比对之前已授精的雌性更大的性兴趣。使用相同的表皮提取物使我们能够通过实验创造出具有相似气味的雌性，而雄性对这类雌性的反应表明它们利用雌性表皮模式进行区分。表皮特征的化学分析显示，雌性表皮模式的个体间差异大于雄性，这可能是由于对雌性发出个体身份信号的选择压力更大。
