背景:亚洲家鼠(Rattustanezumi)和褐鼠(Rattusnorvegicus)是密切相关的物种,在中国南方部分同乡。在过去的20年里,R.tanezumi已在中国向北扩展,并部分取代了本地褐鼠亚种,R.n.羞辱。尽管入侵物种通常比本地物种更具侵略性,我们没有观察到R.tanezumi和R.n.humiliatus之间的种间身体攻击。这里,我们专注于R.tanezumi是否在非身体竞争方面优于R.n.屈辱,主要由化学信号介导。
结果:我们进行了两个实验室实验,以测试驯化的R.tanezumi和R.n.humiliatus的不同范例。在实验1中,我们将每个物种的成年雄性大鼠关在异型或同种对中2个月,用穿孔的镀锌铁片隔开,允许化学刺激和超声波发声的交换。男性尿液气味的性吸引力显示出在用R.n.humiliatus笼中的R.tanezumi增加的趋势(边际意义),与同种配对相比。海马糖皮质激素受体(GR)和脑源性营养因子(BDNF)mRNA在R中上调。humiliatus和R.tanezumi,分别,当大鼠被关在异型对中时。在实验2中,我们将幼年雄性大鼠在相同或不同物种的房间中单独的笼子里饲养2个月,允许化学相互作用。R.tanezumi男性尿液的性吸引力显着增强,但在R.n.humiliatus中,异质特异性线索降低,海马GR和BDNF的mRNA表达被R.n.humiliatus和R.tanezumi,分别。虽然不相同,实验1和2的结果基本一致。
结论:两个实验的结果表明,非物理/慢性种间刺激,尤其是气味信号,在R.n.屈辱和R.tanezumi之间可能会对R.n.屈辱产生负面影响,并对R.tanezumi产生积极影响。我们推断,慢性种间相互作用可能导致R.tanezumi入侵R.n.humiliatus在自然栖息地。
BACKGROUND: The Asian house rat (Rattus tanezumi) and the brown rat (Rattus norvegicus) are closely related species and are partially sympatric in southern China. Over the past 20 years, R. tanezumi has significantly expanded northward in China and partially replaced the native brown rat subspecies, R. n. humiliatus. Although invasive species are often more aggressive than native species, we did not observe interspecific physical aggression between R. tanezumi and R. n. humiliatus. Here, we focused on whether or not R. tanezumi was superior to R. n. humiliatus in terms of nonphysical competition, which is primarily mediated by chemical signals.
RESULTS: We performed two laboratory experiments to test different paradigms in domesticated R. tanezumi and R. n. humiliatus. In Experiment 1, we caged adult male rats of each species for 2 months in heterospecific or conspecific pairs, partitioned by perforated galvanized iron sheets, allowing exchange of chemical stimuli and ultrasonic vocalization. The sexual attractiveness of male urine odor showed a tendency (marginal significance) to increase in R. tanezumi caged with R. n. humiliatus, compared with those in conspecific pairs. Hippocampal glucocorticoid receptor (GR) and brain-derived nutrition factor (BDNF) mRNA were upregulated in R. n. humiliatus and R. tanezumi, respectively, when the rats were caged in heterospecific pairs. In Experiment 2, we kept juvenile male rats in individual cages in rooms with either the same or the different species for 2 months, allowing chemical interaction. The sexual attractiveness of male urine was significantly enhanced in R. tanezumi, but reduced in R. n. humiliatus by heterospecific cues and mRNA expression of hippocampal GR and BDNF were upregulated by heterospecific cues in R. n. humiliatus and R. tanezumi, respectively. Although not identical, the results from Experiments 1 and 2 were generally consistent.
CONCLUSIONS: The results of both experiments indicate that nonphysical/chronic interspecific stimuli, particularly scent signals, between R. n. humiliatus and R. tanezumi may negatively affect R. n. humiliatus and positively affect R. tanezumi. We infer that chronic interspecific interactions may have contributed to the invasion of R. tanezumi into the range of R. n. humiliatus in natural habitats.