Stabilizing selection on blue tit fledgling mass in the presence of sparrowhawks
Stabilizing selection on blue tit fledgling mass in the presence of sparrowhawks
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DOI：
10.1098/rspb.1998.0392
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发表时间：
1998-06-07
影响因子：
4.7
通讯作者：
Matthysen, E
中科院分区：
文献类型：
--
作者：
Adriaensen, F;Dhondt, AA;Matthysen, E
与英国大山雀一样，比利时蓝山雀在冬季有雀鸟的时候身体质量较低。由于身体质量影响小鸟的机动性，山雀可以通过改变冬天携带的额外脂肪的数量来平衡饥饿的风险和鹰的捕食风险。在冬季，麻雀对幼鸟和没有经验的幼鸟的捕食压力至少与对成鸟的捕食压力一样大。因此，我们预计，在雀鸟的存在下，山雀羽翼未丰的身体质量也可以减少。在一对麻雀在研究场地安顿下来后的几年里，与没有麻雀的年份相比，蓝山雀幼鸟的平均体重要低一些。此外，幼体存活率与幼体质量之间的关系曲线的形状发生了变化，因为最重幼体的存活率降低了，这改变了幼体存活率作为体重函数的选择差异，从定向到稳定。在七项已发表的关于山雀羽翼未丰的体重与生存关系的研究中，所有三项在没有雀鹰的情况下进行的研究都显示，最重的幼鸟的存活率最高，而在所有四项有雀鹰参与的研究中，情况不再是这样。
Like British great tits, Belgian blue tits have a lower winter body mass when sparrowhawks are present. Since body mass affects manoeuvrability in small birds, tits may balance the risks of starvation and the risk of hawk predation by varying the amount of extra fat carried during winter. Predation pressure by sparrowhawks on young and inexperienced fledglings is at least as intense as that on the adults during winter. We therefore expected that tit fledgling body mass could also be reduced in the presence of sparrowhawks. In the years after one pair of sparrowhawks settled in a study plot, the mean body mass of blue tit fledglings was lower compared with that in years when there were no sparrowhawks. Furthermore, the shape of the curve relating juvenile survival to fledging mass changed, because the survival of the heaviest fledglings was reduced, which altered the selection differential of juvenile survival as a function of body mass from directional to stabilizing. Of seven published studies on the fledgling body mass-survival relation in tits, all three of the studies conducted in the absence of sparrowhawks showed the highest survival rates for the heaviest young, whereas in all four studies with sparrowhawks present this was no longer the case.