The ability to recognize and differentiate between conspecifics and heterospecifics as well as their signals is critical for the coexistence of closely related species. In the genus Rattus, species are morphologically similar and multiple species often coexist. Here, we investigated the interspecific recognition and signal differentiation of two sympatric rat species, the brown rat (Rattus norvegicus, RN) and the Asian house rat (R. tanezumi, RT). In a two-way choice test, both RN and RT females showed a preference for conspecific male rats to heterospecific ones. RT females showed a significant preference for accessible urine of males of same species to those of other species, but not for the inaccessible urine. On the other hand, there were significant differences in the structural characteristics of the ultrasonic vocalization emitted by males of these two rat species. Sodium dodecyl sulfate‒polyacrylamide gel electrophoresis (SDS‒PAGE) and isoelectric focusing electrophoresis (IEF) unveiled that major urinary proteins (MUPs) in voided urine were more highly expressed in RN males vs RT males. The interspecific differences of urinary volatile compounds were also discussed. In conclusion, female rats had the ability to distinguish between males of either species.

中文翻译：

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物种识别以及两种共存黄鼠物种之间化学和超声波信号的差异

识别和区分同种和异种及其信号的能力对于密切相关物种的共存至关重要。黄毛鼠属中，物种形态相似，常有多个物种共存。在这里，我们研究了两种同域大鼠物种：褐鼠（Rattusnorvegicus，RN）和亚洲家鼠（R. tanezumi，RT）的种间识别和信号分化。在双向选择测试中，RN 和 RT 雌性均表现出对同种雄性大鼠的偏好，而不是异种雄性大鼠。RT 雌性对同种雄性可接近的尿液表现出明显的偏好，但对不可接近的尿液则没有显着偏好。另一方面，这两种大鼠的雄性发出的超声波发声的结构特征存在显着差异。十二烷基硫酸钠聚丙烯酰胺凝胶电泳 (SDS-PAGE) 和等电聚焦电泳 (IEF) 揭示，与 RT 男性相比，排尿尿液中的主要尿蛋白 (MUP) 在 RN 男性中表达更高。还讨论了尿液挥发性化合物的种间差异。总之，雌性老鼠有能力区分这两个物种的雄性。还讨论了尿液挥发性化合物的种间差异。总之，雌性老鼠有能力区分这两个物种的雄性。还讨论了尿液挥发性化合物的种间差异。总之，雌性老鼠有能力区分这两个物种的雄性。