van Dongen Wouter F D
Department of Zoology, University of Melbourne, Melbourne, Australia.
Naturwissenschaften. 2008 Jun;95(6):537-45. doi: 10.1007/s00114-008-0356-1. Epub 2008 Mar 5.
Male paternity assurance behaviour during the female fertile period has been widely documented amongst birds. In contrast, how sex-specific behavioural strategies vary with local breeding synchrony levels remains largely unknown. This is important because, in many species, intra-population patterns of extra-pair fertilisation rates, and hence cuckoldry risk, are known to vary with the number of simultaneously fertile females. Each sex may therefore differ in how they behave towards male conspecifics during different degrees of breeding synchrony. Here I provide evidence of such sex-specific differences in the golden whistler (Pachycephala pectoralis), a species in which within-pair paternity assurance is negatively associated with breeding synchrony. Via simulated territorial intrusions using decoy males, I show that males, but not females, increase levels of aggression to male intruders during periods of low synchrony, possibly because cuckoldry risk is greatest during this period. In addition, males appear to invest more effort into mate guarding after, but not before, territorial intrusions during this period. These inter-sexual differences may reflect conflicts in interest between the sexes, with females consistently showing interest in males during the fertile period regardless of synchrony levels and males investing more resources into expelling intruders when the risk of paternity loss is greatest. This study thus provides evidence that males may be able to detect variation in breeding synchrony and cuckoldry risk and adjust their paternity assurance behaviour accordingly.
在鸟类中，雄性在雌性排卵期的亲权保障行为已有广泛记载。相比之下，性别特异性行为策略如何随当地繁殖同步水平变化，在很大程度上仍不为人知。这一点很重要，因为在许多物种中，已知种群内的婚外受精率模式以及由此产生的戴绿帽风险会随同时处于排卵期的雌鸟数量而变化。因此，在不同程度的繁殖同步期，两性对同种雄性的行为表现可能会有所不同。在此，我提供了金啸鹟（Pachycephala pectoralis）存在这种性别特异性差异的证据，在该物种中，配偶内亲权保障与繁殖同步呈负相关。通过使用雄性诱饵模拟领地入侵，我发现，在同步性较低的时期，雄性而非雌性会增加对雄性入侵者的攻击水平，这可能是因为在此期间戴绿帽风险最大。此外，在此期间，雄性似乎在领地入侵之后而非之前投入更多精力进行配偶守护。这些两性差异可能反映了两性之间的利益冲突，雌性在排卵期始终对雄性表现出兴趣，而不论同步水平如何，而雄性在亲权丧失风险最大时会投入更多资源驱逐入侵者。因此，这项研究提供了证据，表明雄性可能能够察觉到繁殖同步和戴绿帽风险的变化，并据此调整其亲权保障行为。
