Arnold Kathryn E, Ramsay Scot L, Donaldson Christine, Adam Aileen
Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK.
Proc Biol Sci. 2007 Oct 22;274(1625):2563-9. doi: 10.1098/rspb.2007.0687.
Early nutrition shapes life history. Parents should, therefore, provide a diet that will optimize the nutrient intake of their offspring. In a number of passerines, there is an often observed, but unexplained, peak in spider provisioning during chick development. We show that the proportion of spiders in the diet of nestling blue tits, Cyanistes caeruleus, varies significantly with the age of chicks but is unrelated to the timing of breeding or spider availability. Moreover, this parental prey selection supplies nestlings with high levels of taurine particularly at younger ages. This amino acid is known to be both vital and limiting for mammalian development and consequently found in high concentrations in placenta and milk. Based on the known roles of taurine in mammalian brain development and function, we then asked whether by supplying taurine-rich spiders, avian parents influence the stress responsiveness and cognitive function of their offspring. To test this, we provided wild blue tit nestlings with either a taurine supplement or control treatment once daily from the ages of 2-14 days. Then pairs of size- and sex-matched siblings were brought into captivity for behavioural testing. We found that juveniles that had received additional taurine as neonates took significantly greater risks when investigating novel objects than controls. Taurine birds were also more successful at a spatial learning task than controls. Additionally, those individuals that succeeded at a spatial learning task had shown intermediate levels of risk taking. Non-learners were generally very risk-averse controls. Early diet therefore has downstream impacts on behavioural characteristics that could affect fitness via foraging and competitive performance. Fine-scale prey selection is a mechanism by which parents can manipulate the behavioural phenotype of offspring.
早期营养塑造生命历程。因此，父母应提供能优化后代营养摄入的饮食。在许多雀形目鸟类中，雏鸟发育期间蜘蛛供应量往往会出现一个常见但无法解释的峰值。我们发现，蓝山雀（Cyanistes caeruleus）雏鸟饮食中蜘蛛的比例会随雏鸟年龄显著变化，但与繁殖时间或蜘蛛可获得性无关。此外，这种亲代猎物选择为雏鸟提供了高水平的牛磺酸，尤其是在雏鸟较小时。已知这种氨基酸对哺乳动物发育至关重要且具有限制性，因此在胎盘和乳汁中含量很高。基于牛磺酸在哺乳动物大脑发育和功能中的已知作用，我们进而探讨鸟类父母通过提供富含牛磺酸的蜘蛛，是否会影响其后代的应激反应能力和认知功能。为了验证这一点，我们从2至14日龄开始，每天为野生蓝山雀雏鸟提供一次牛磺酸补充剂或对照处理。然后将大小和性别匹配的成对雏鸟同胞放入笼中进行行为测试。我们发现，幼鸟在幼雏期额外摄入牛磺酸后，在探究新物体时比对照组冒的风险显著更大。摄入牛磺酸的鸟类在空间学习任务中也比对照组更成功。此外，那些在空间学习任务中成功的个体表现出中等程度的冒险行为。未学会的个体通常是非常规避风险的对照组。因此，早期饮食对行为特征有下游影响，可能通过觅食和竞争表现影响适应性。精细的猎物选择是父母能够操纵后代行为表型的一种机制。
