Data from: Relatedness and spatial proximity as determinants of host-parasite interactions in the brood parasitic Barrow's goldeneye (Bucephala islandica)

Recent studies which have found evidence for kin-biased egg donation have sparked interest in re-assessing the parasitic nature of conspecific brood parasitism (CBP). Since host-parasite kinship is essential for mutual benefits to arise from CBP, we explored the role of relatedness in determining the behaviour of conspecific nest parasites and their hosts in nesting female Barrow's goldeneyes (Bucephala islandica), a duck in which CBP is common. The results revealed that the amount of parasitism increased with host-parasite relatedness, the effect of which was independent of geographic proximity of host and parasite nests. Proximity per se was also positively associated with the amount of parasitism. Furthermore, while hosts appeared to reduce their clutch size as a response to the presence of parasitic eggs, the magnitude of host clutch reduction also tended to increase with increasing relatedness to the parasite. Hence, our results indicate that both relatedness and spatial proximity are important determinants of CBP, and that host clutch reduction may be an adaptation to nest parasitism, modulated by host-parasite relatedness. Taken together, the results provide a demonstration that relatedness influences host and parasite behaviour in Barrow's goldeneyes, resulting in kin-biased egg donation.

近期有研究发现了亲属偏向性寄卵的证据，这引发了学界重新评估同种巢寄生（conspecific brood parasitism, CBP）寄生本质的兴趣。鉴于寄主与寄生者的亲缘关系是同种巢寄生产生互利关系的必要条件，本研究以巢寄生现象普遍的巴罗金眼鸭（Bucephala islandica）的筑巢雌性个体为研究对象，探讨了亲缘关系在决定同种巢寄生者及其寄主行为中的作用。研究结果显示，寄生程度随寄主与寄生者的亲缘关系提升而升高，且该效应不受寄主与寄生者巢穴地理距离的影响。就地理距离本身而言，其与寄生程度也呈正相关关系。此外，尽管寄主似乎会因寄生卵的存在而减少自身窝卵数，但寄主缩减窝卵数的幅度也会随其与寄生者亲缘关系的提升而增大。因此，本研究结果表明，亲缘关系与空间距离均是同种巢寄生的重要影响因素，且寄主缩减窝卵数或许是应对巢寄生的一种适应性策略，其强度受寄主与寄生者亲缘关系的调控。综上，本研究结果证实，在巴罗金眼鸭中，亲缘关系会影响寄主与寄生者的行为，进而产生亲属偏向性寄卵现象。