近日，行为生态学领域刊物《行为生态学》（Behavioral Ecology）在线发表了中科院成都生物研究所两栖爬行动物研究室唐业忠课题组研究人员的研究成果，研究发现动物也有“面子”问题。
雄性之间竞争的目的大多是为了获得资源、领地、配偶，而最终目的则是为了成功交配，以繁殖后代。雄性之间的竞争往往伴随着高能量消耗和被天敌捕食的巨大风险。然而，雄性是否能获得配偶，最终决定权却掌握在雌性手中。因此，可以推测的是：雌性的存在与否以及雌性对雄性的态度有可能影响雄性之间的竞争策略。例如，对于人类来说，在有女性在场时，男性更勇敢。那么，对于动物来讲，事实是否果真如此？
崔建国博士设计了一个实验，在动物身上验证了这一假设。通常情况下，两只雄性非洲爪蟾（Xenopus laevis）放在同一只缸中竞叫时，会产生明显的胜利者和失败者，失败者受到明显地压制，较少发出鸣叫。当研究者给成对的雄性竞争者播放雌性接受鸣叫（处于发情状态的鸣叫声）时，胜利者和失败者均显著增加鸣叫。有趣的是，有一半原来的失败者能反败为胜，转变成胜利者。而且，相关分析也表明，在雄性竞争前（即每只缸中放一只动物单独鸣叫），动物的鸣叫时间与体重呈显著正相关（即体重越大，鸣叫时间越长），而当两只雄性放在同一只缸中竞争时，这种相关关系消失，说明部分“机会主义者”隐藏了其真实的实力，采取保守的竞争策略，而当听到雌性接受鸣叫时，这种相关关系重新出现，说明部分“机会主义者”在有雌性出现时，采取激进的竞争策略，露出真本事，奋起反击，从而反败为胜。
本研究揭示：雄性之间的竞争策略可根据雌性的态度而转变，从而有助于我们理解为什么女性在场时男性比较要面子这一问题的生物学基础。研究得到国家自然科学基金青年基金、中国科学院重要方向项目子课题-生物适应与协同进化和“百人计划”项目的资助。（生物谷Bioon.com）
doi:10.1093/beheco/arr187
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PMID:
Male competition strategies change when information concerning female receptivity is available
Fei Xua, Jianguo Cuia, Jing Songa, Steven E. Brauthb and Yezhong Tanga
Males compete for access to resources or females or to influence female mate choice in many animal species. Male competitive activities are accompanied by high-energy expenditure and increased risk of predator detection. We therefore hypothesized that information predicting female receptivity could affect male competition strategies in species in which such information is available to males. To test this hypothesis, male–male vocal competition was assessed in Xenopus laevis, a species in which females can produce receptive (rapping) and unreceptive (ticking) calls. Male vocalizations were recorded when 1) males called alone, 2) 2 paired males with similar body mass called competitively and established dominance, and 3) the paired males called when listening to playbacks of either rapping or ticking calls. On average, rapping but not ticking playbacks increased male calling and in many cases induced previously nondominant males to call more than their rivals. Moreover, males adopted either of 2 competitive strategies: an assertive strategy in which some individuals always called at a high rate and an opportunistic strategy in which some individuals only called at a high rate in the presence of receptive female call playbacks. Body mass and call rate were correlated only when males called alone or when rapping calls were played back. These results support the idea that male–male competition strategies can be influenced by information indicating that receptive females are present.
