急性捕食风险不能完全限制饥饿 雌性长爪沙鼠的觅食活动
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国家自然科学基金项目(No. 31872232)


The Acute Predation Risk Could Not Completely Inhibit the Foraging Activities in Starving Female Mongolian Gerbils (Meriones unguiculatus)
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    摘要:

    觅食活动是动物生存和繁殖所必需的基本的活动,受个体生理状态(如饥饿)和环境状况(如捕食、食物可利用性)时空变化的影响,能量状态-风险分配假说指出,动物在应对不同风险时会优化觅食和反捕食努力的时间和能量分配。然而,有关啮齿动物觅食决策的能量状态-捕食风险分配假说的研究结论尚不统一。本研究在野外实验室以艾鼬(Mustela eversmannii)气味作为捕食风险刺激源,以非捕食者(马)气味源作为对照,首先通过Y型观测箱检验雌性饥饿长爪沙鼠(Meriones unguiculatus)对捕食者气味的辨别能力(Wilcoxon 秩检验);在此基础上通过中立场行为观测箱分别测定饥饿雌鼠在“有食物和天敌气味源”与“有食物和非天敌气味源”环境下的觅食活动,采用Mann-Whitney Z检验比较两者间的行为差异,以验证急性捕食风险限制饥饿沙鼠觅食活动的假设,并探讨动物在饥饿风险与捕食风险共存情况下的觅食行为对策。结果显示,(1)长爪沙鼠对天敌气味反应明显,厌恶和回避有较高潜在捕食风险的空间;(2)虽然觅食潜伏期在捕食风险存在时有所增加,但急性捕食风险并未影响饥饿沙鼠的觅食频次,沙鼠通过缩短每次觅食的持续时间来应对捕食风险;与此同时,(3)饥饿沙鼠在急性捕食风险条件下对环境探究的次数明显增加,一定程度上提高反捕食努力,且自我修饰表现显著,以缓释捕食压力的恐惧效应。这些结果表明,急性捕食风险不能完全抑制饥饿沙鼠的觅食努力,在有捕食风险情况下,饥饿的长爪沙鼠会权衡觅食获取能量和避免捕食的收益和代价,优化觅食策略。本研究结果支持能量状态-风险分配假说关于在短期高风险情况下反捕食努力分配更多,但当动物在饥饿风险持续时间比例显著增加时,动物最终也必须在高风险情况下觅食的预测,也反映了长爪沙鼠对食物资源不可预测及捕食风险高的干旱半干旱荒漠环境的行为适应对策。

    Abstract:

    Foraging is a fundamental behavior to ensure animals’ survival and reproduction. Foraging decisions should balance the risks of starvation and predation which usually varied both spatially and temporally in the wild. The energetic state-risk allocation hypothesis presented that the optimal trade-off between energetic gain from foraging and avoidance of predation should depend on animals’ current physiological states (e.g., hunger), on current environmental states (e.g. actual predation risk, food availability), and perhaps also on past and expected future states. However, in terms of the model of energetic state and predation risk allocation, studies in rodents have yielded mixed results. Therefore, we used a Y-shaped maze by a 10-min behavioral test to measure the discrimination to the predator odor of a Steppe Polecat (Mustela eversmannii) or no-predator (i.e. horse) odor in female Mongolian Gerbils (Meriones unguiculatus) deprived food for 18 h in field laboratory conditions. Then we investigated the feeding and antipredator efforts of the fasted female gerbils in the presence of predator odor with food or those of in the control no-predator odor with food at a neutral arena. We aimed to test the hypothesis that acute predation risk inhibited the foraging effort of the starving gerbils, and then to address the trade-off between the starvation and predation risk in the foraging decision of gerbils, as a desert rodent. We found that both the frequency and the duration of visiting the predator odor selection box was significantly less than that of visiting the control box (Wilcoxon signed ranks test: frequency, Z = 2.405, P = 0.016; duration, Z = 2.803, P = 0.005; Table 1), which indicated a remarkable aversive or fear response to the steppe polecat odors in female Mongolian gerbils. Furthermore, we observed that starving gerbils displayed their foraging effort both in the treatment with a predation risk and without predation risk, e.g. unchanged their foraging frequency compared to under the predation risk and under the control situation (Mann-Whitney test: Z = 1.514, P = 0.130; Fig. 2). It was just that,compared with the foraging latency (58.6 ± 35.5 s) under control situation,the starving gerbils under predation risks increased the foraging latency (110.4 ± 57.9 s), delaying their foraging (Mann-Whitney test: Z = 2.068, P = 0.039; Fig. 1), yet decreased the duration per foraging (Mann-Whitney test: Z = 2.856, P = 0.004; Fig. 1). Additionally, we noted that gerbils were higher in the effort of the up-investigating to the space for vigilance (Mann-Whitney test: frequency: Z = 3.187, P = 0.001; Fig.2; duration, Z = 2.725, P = 0.006; Fig. 3) and self-grooming for releasing fear in the treatment with the predation odor risk (Mann-Whitney test: Z = 2.289, P = 0.022, Fig. 2). Our results, thus, revealed that the acute predation risk could not completely inhibit the foraging activities in starving female Mongolian gerbils, and partly supported the energetic state-predation risk allocation hypothesis. These results suggested that the gerbil could respond to the hazard of starvation and predation by risk-adjusting or balancing, and trade off the energetic gain from foraging and cost of predation maximizing the current or lifetime fitness, which benefited to the Mongolian gerbils adapt to desert environment characterized by largely unpredictable food resources and relative higher predation-risk.

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刘伟,陈竟峰,王德华,钟文勤.2020.急性捕食风险不能完全限制饥饿 雌性长爪沙鼠的觅食活动.动物学杂志,55(5):541-551.

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  • 收稿日期:2020-04-03
  • 最后修改日期:2020-08-21
  • 录用日期:2020-08-20
  • 在线发布日期: 2020-10-13
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