Mainwaring Mark C, Hartley Ian R
Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
Behav Processes. 2020 Apr;173:104026. doi: 10.1016/j.beproc.2019.104026. Epub 2020 Jan 24.
Early theoretical models predicted that over evolutionary timescales, changes in effort by one biparental parent should result in incomplete compensation by the other. Empirical studies, however, report responses ranging from no compensation through to complete compensation which may mean that parents respond to each other's efforts over short time scales, as predicted by some recent theoretical models. Few studies have examined behavioural changes over short time periods which mimic the onset of reduced effort so we removed one blue tit (Cyanistes caeruleus) parent for 20 min during nestling provisioning. We then quantified the provisioning rates of both parents for 60 min 'pre-removal', the non-removed partner during the 20 min 'removal' period and both parents for 60 min 'post-removal'. When compared to pre-removal, both sexes reduced their provisioning rates during the removal stage and also during the post-removal stage. There were, however, sex-specific provisioning patterns in the hour after the parent was returned because after females were released, males began provisioning at a relatively high rate and then maintained that rate across the hour after removal whereas after males were released, females began provisioning at a low rate but significantly increased thereafter. There was no long term effect on offspring fitness, which probably reflects the short time parents were removed and so we conclude that parents with biparental care adjust their provisioning rates to successfully overcome very short term decreases in care.
早期的理论模型预测，在进化时间尺度上，双亲中一方投入的变化应会导致另一方的补偿不完整。然而，实证研究报告的反应范围从无补偿到完全补偿，这可能意味着父母会在短时间尺度上对彼此的投入做出反应，正如一些近期理论模型所预测的那样。很少有研究考察过在短时间内模拟投入减少开始时的行为变化，因此我们在雏鸟喂养期间将一只蓝山雀（蓝冠山雀）亲鸟移走了20分钟。然后，我们对双亲在“移走前”60分钟、“移走”20分钟期间未被移走的一方以及“移走后”60分钟的喂养率进行了量化。与移走前相比，两性在移走阶段以及移走后阶段都降低了喂养率。然而，在亲鸟返回后的一小时内存在性别特异性的喂养模式，因为雌鸟被放回后，雄鸟开始以相对较高的速率喂养，并且在移走后的一小时内保持该速率，而雄鸟被放回后，雌鸟开始时喂养速率较低，但此后显著增加。对后代的适应性没有长期影响，这可能反映了亲鸟被移走的时间较短，因此我们得出结论，双亲照料的亲鸟会调整它们的喂养率，以成功克服照料方面非常短期的减少。
