Antonov Anton, Stokke Bård G, Moksnes Arne, Røskaft Eivin
Department of Biology, Norwegian University of Science and Technology (NTNU), Realfagbygget, Trondheim 7491, Norway.
Naturwissenschaften. 2007 Apr;94(4):307-12. doi: 10.1007/s00114-006-0189-8. Epub 2006 Dec 12.
Coevolution is defined as specialized relationships between species that lead to a reciprocal evolutionary change. A particularly suitable model system for studying coevolution is the interactions between obligate avian brood parasites and their hosts. The common cuckoo (Cuculus canorus, hereafter cuckoo) is a well-known brood parasite, which utilizes a range of smaller passerines as hosts. However, warblers of the genus Hippolais have rarely been reported as being victims of cuckoos, and furthermore, few data exist on the occurrence of antiparasite defenses in these hosts. In this study, we examined possible host-parasite coevolution between cuckoos and eastern olivaceous warblers (Hippolais pallida elaeica, hereafter olivaceous warblers) in three closely situated areas in northwestern Bulgaria. The olivaceous warbler has never been reported to be a regular cuckoo host. However, the present study, carried out in 2001-2003 shows that the olivaceous warbler is regularly and heavily parasitized by the cuckoo in this area. Parasitism rate was high (26.6%, 34/128) and consistent among years, with some variation between areas. The cuckoo egg mimicry was moderately good, and olivaceous warbler rejection rate of such eggs was 50%. Cuckoo eggs laid in olivaceous warbler nests had a whitish to whitish-green ground color, and the majority appeared to be distinctly different from cuckoo eggs found in other host species in the area. The olivaceous warbler proved to be a rather good host for cuckoos as 20.6% (7/34) of cuckoo eggs laid produced fledglings, a breeding success comparable to other suitable hosts in Europe. This is the first in-depth study of brood parasitism in a warbler of the genus Hippolais, and cuckoos parasitizing olivaceous warblers probably represent a previously unknown gens.
协同进化被定义为物种之间导致相互进化变化的特殊关系。一个特别适合研究协同进化的模型系统是专性鸟类巢寄生者与其宿主之间的相互作用。普通杜鹃(Cuculus canorus,以下简称杜鹃)是一种著名的巢寄生者,它利用一系列较小的雀形目鸟类作为宿主。然而,很少有关于希坡拉莺属莺类被杜鹃寄生的报道,而且关于这些宿主中抗寄生虫防御的发生情况的数据也很少。在本研究中,我们在保加利亚西北部三个相邻的地区研究了杜鹃与东橄榄林莺(Hippolais pallida elaeica,以下简称橄榄林莺)之间可能的宿主 - 寄生虫协同进化。橄榄林莺从未被报道为杜鹃的常规宿主。然而,2001年至2003年进行的本研究表明,在该地区橄榄林莺经常且大量地被杜鹃寄生。寄生率很高(26.6%,34/128)且多年间保持一致,不同地区之间存在一些差异。杜鹃卵的拟态中等良好,橄榄林莺对这类卵的拒绝率为50%。产在橄榄林莺巢中的杜鹃卵底色为白色至白绿色,大多数看起来与该地区其他宿主物种巢中的杜鹃卵明显不同。事实证明,橄榄林莺对杜鹃来说是相当合适的宿主,因为所产杜鹃卵中有20.6%(7/34)孵化出了雏鸟,繁殖成功率与欧洲其他合适宿主相当。这是对希坡拉莺属莺类巢寄生现象的首次深入研究,寄生橄榄林莺的杜鹃可能代表一个此前未知的类群。