Cryptic cuckoo eggs hide from competing cuckoos
Cryptic cuckoo eggs hide from competing cuckoos
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DOI：
10.1098/rspb.2014.1014
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发表时间：
2014-10-07
影响因子：
4.7
通讯作者：
Langmore, Naomi E.
中科院分区：
文献类型：
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作者：
Gloag, Ros;Keller, Laurie-Anne;Langmore, Naomi E.
杜鹃和它们的宿主之间的物种间军备竞赛产生了引人注目的模仿例子，寄生虫卵进化成与宿主卵的外观相匹配，从而逃避宿主的清除。然而，某些青铜杜鹃物种的产卵是神秘的，而不是模仿的。这些卵被一种低亮度的色素覆盖，将它们伪装在宿主巢穴黑暗的内部。我们调查了杜鹃卵隐蔽是否可能来自相同的共同进化过程，即已知有利于卵模仿的共同进化过程。我们将高亮度和低亮度彩蛋添加到大嘴巨嘴龙的巢中，这是小青铜杜鹃(Chalcites Minutillus)的宿主。长臂猿很少排斥任何一种蛋，也不排斥天然的杜鹃蛋。相比之下，杜鹃在下蛋前会定期从巢中取出一个蛋，而且移除高亮度模型的可能性是低亮度模型的五倍。鉴于我们发现三分之一的寄生巢被多只杜鹃利用，我们的结果表明杜鹃之间的竞争一直是卵隐蔽的关键选择因素。在这种种内军备竞赛中，密码可能比模仿更受青睐，因为它可以将卵子取出的风险降低到低于机会的水平。
Interspecific arms races between cuckoos and their hosts have produced remarkable examples of mimicry, with parasite eggs evolving to match host egg appearance and so evade removal by hosts. Certain bronze-cuckoo species, however, lay eggs that are cryptic rather than mimetic. These eggs are coated in a low luminance pigment that camouflages them within the dark interiors of hosts' nests. We investigated whether cuckoo egg crypsis is likely to have arisen from the same coevolutionary processes known to favour egg mimicry. We added high and low luminance-painted eggs to the nests of large-billed gerygones (Gerygone magnirostris), a host of the little bronze-cuckoo (Chalcites minutillus). Gerygones rarely rejected either egg type, and did not reject natural cuckoo eggs. Cuckoos, by contrast, regularly removed an egg from clutches before laying their own and were five times more likely to remove a high luminance model than its low luminance counterpart. Given that we found one-third of all parasitized nests were exploited by multiple cuckoos, our results suggest that competition between cuckoos has been the key selective agent for egg crypsis. In such intraspecific arms races, crypsis may be favoured over mimicry because it can reduce the risk of egg removal to levels below chance.