Bize Pierre, Roulin Alexandre, Richner Heinz
Division of Evolutionary Ecology, Department of Zoology, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland.
Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
Oecologia. 2002 Jul;132(2):231-234. doi: 10.1007/s00442-002-0980-y. Epub 2002 Jul 1.
A positive correlation between egg size, early growth and nestling survival has been frequently reported in the ornithological literature. Albeit of interest, most of these studies did not determine whether the relationship between egg size, early growth and nestling survival was confounded by the quality of rearing conditions. However, this is of importance in order to assess the extent to which a life-history trait like egg size causally affects fitness. In a colony of the alpine swift Apus melba, we cross-fostered complete clutches between nests to determine the relative contribution of egg size and rearing condition on nestling growth and survival. In foster nests, nestlings that hatched out of larger eggs were significantly heavier at birth and at the age of 10 days; at 25 days, however, the relationship was no longer significant. The likelihood of a chick surviving from birth to 25 days of age was not correlated with its original egg size, but with the size of the eggs laid by its foster parents. This experiment therefore lends support to the hypothesis that in the alpine swift the relationship between egg size and nestling growth and survival is mainly due to a covariation between egg size and parental care rather than to a direct contribution of egg size.
鸟类学文献中经常报道蛋的大小、早期生长和雏鸟存活率之间存在正相关关系。尽管这些研究很有趣，但大多数研究并未确定蛋的大小、早期生长和雏鸟存活率之间的关系是否受到饲养条件质量的混淆。然而，这对于评估蛋大小等生活史特征对适合度的因果影响程度至关重要。在高山雨燕Apus melba的一个群体中，我们在巢间交叉寄养完整的一窝蛋，以确定蛋大小和饲养条件对雏鸟生长和存活的相对贡献。在寄养巢中，由较大蛋孵化出的雏鸟出生时和10日龄时明显更重；然而，在25日龄时，这种关系不再显著。雏鸟从出生到25日龄存活的可能性与其原蛋大小无关，而是与其养父母所产蛋的大小有关。因此，该实验支持了这样一种假设，即在高山雨燕中，蛋大小与雏鸟生长和存活之间的关系主要是由于蛋大小与亲代抚育之间的协变，而不是蛋大小的直接作用。
