本期Nature Communications上發(fā)表的一篇論文報(bào)告說(shuō),，杜鵑會(huì)在同一寄主巢中反復(fù)下蛋,，目的是增加它們的蛋被寄主父母接受的可能性,。這項(xiàng)研究表明,，這一方法會(huì)擾亂“養(yǎng)父母”用來(lái)識(shí)別它們自己的蛋的認(rèn)知過(guò)程,，降低杜鵑的蛋被拒絕的風(fēng)險(xiǎn),。
很多種杜鵑在其他鳥(niǎo)的巢中下蛋，并且形成了逃避被拒絕的一些策略,，如模仿寄主蛋的外觀(guān),。為此，作為寄主的鳥(niǎo)也掌握了區(qū)分它們自己的蛋與杜鵑蛋的方法,。除了利用以前有關(guān)它們自己蛋的知識(shí)外,，它們似乎還會(huì)尋找在顏色、圖案和大小上的差別,，然后將不符合它們內(nèi)部模板的蛋扔掉,。通過(guò)研究撒哈拉以南非洲的一種本地杜鵑和它們的寄主（褐頭鷦鶯），Martin Stevens及同事發(fā)現(xiàn),，任何一個(gè)巢中所下的杜鵑蛋的數(shù)量的增加,，都會(huì)導(dǎo)致寄主鳥(niǎo)的這些分辨過(guò)程的擾亂以及寄生蛋更大程度的接受。該研究小組還發(fā)現(xiàn),，寄生蛋的數(shù)量越大,，寄主就需要在顏色上有更大差別才能正確識(shí)別它們自己的蛋和拒絕杜鵑的蛋,。
生物谷推薦的英文摘要
Nature Communications DOI:10.1038/ncomms3475
Repeated targeting of the same hosts by a brood parasite compromises host egg rejection
Martin Stevens，Jolyon Troscianko & Claire N. Spottiswoode
Cuckoo eggs famously mimic those of their foster parents to evade rejection from discriminating hosts. Here we test whether parasites benefit by repeatedly parasitizing the same host nest. This should make accurate rejection decisions harder,， regardless of the mechanism that hosts use to identify foreign eggs. Here we find strong support for this prediction in the African tawny-flanked prinia (Prinia subflava),， the most common host of the cuckoo finch (Anomalospiza imberbis). We show experimentally that hosts reject eggs that differ from an internal template， but crucially,， as the proportion of foreign eggs increases,， hosts are less likely to reject them and require greater differences in appearance to do so. Repeated parasitism by the same cuckoo finch female is common in host nests and likely to be an adaptation to increase the probability of host acceptance. Thus， repeated parasitism interacts with egg mimicry to exploit cognitive and sensory limitations in host defences.
