The evolution of animal brain size and cognitive ability is a topic of central significance in evolutionary ecology. Interspecific brood parasitism imposes severe selection pressures on hosts favoring the evolution of cuckoo egg recognition and rejection. However, recognizing and rejecting foreign parasitic eggs are enormous cognitive challenges for cuckoo hosts, which might select for an increase in brain size in birds with this capacity. To explore the association between cuckoo parasitism and the evolution of brain size in cinereous tits (Parus cinereus), we used two types of experimental parasitic eggs, real mimetic white-rumped munia (Lonchura striata) eggs and non-mimetic blue model eggs, to test the egg recognition ability of female cinereous tits, thereby comparing brain size variation among individuals that were able to recognize foreign eggs and those that lacked this ability. Interestingly, our results however did not support the prediction that cuckoo parasitism selects for an increase in brain size of host birds, since brain size of egg rejecters was not significantly larger than that of accepters. Hence, this study suggested that the evolution of cognitive ability did not allow recognition of foreign eggs by female cinereous tits. That was the case despite the evolution of a larger brain may have allowed for a reduction in the cost of brood parasitism by cuckoos.

中文翻译：

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布谷鸟宿主的卵子识别和大脑大小

动物大脑大小和认知能力的进化是进化生态学中具有核心意义的话题。种间繁殖寄生对寄主施加了严重的选择压力，有利于布谷鸟卵识别和排斥的进化。然而，识别和拒绝外来寄生卵对于杜鹃宿主来说是巨大的认知挑战，这可能会选择增加具有这种能力的鸟类的大脑大小。为了探索杜鹃寄生与灰山雀（Parus cinereus）大脑大小进化之间的关联，我们使用了两种类型的实验寄生卵，真正的拟态白腰鲟（Lonchura striata）卵和非拟态蓝色模型卵。测试雌性乳头的卵子识别能力，从而比较能够识别外来卵的个体和缺乏这种能力的个体之间的大脑大小差异。有趣的是，我们的结果并不支持杜鹃寄生选择增加寄主鸟类大脑大小的预测，因为鸡蛋排斥者的大脑大小并不明显大于接受者的大脑大小。因此，这项研究表明，认知能力的进化不允许雌性灰山雀识别外来卵。尽管更大的大脑的进化可能允许降低杜鹃寄生的成本，但情况仍然如此。因为鸡蛋排斥者的大脑大小并不明显大于接受者的大脑大小。因此，这项研究表明，认知能力的进化不允许雌性灰山雀识别外来卵。尽管更大的大脑的进化可能允许降低杜鹃寄生的成本，但情况仍然如此。因为鸡蛋排斥者的大脑大小并不明显大于接受者的大脑大小。因此，这项研究表明，认知能力的进化不允许雌性灰山雀识别外来卵。尽管更大的大脑的进化可能允许降低杜鹃寄生的成本，但情况仍然如此。