Gasparini Julien, Roulin Alexandre, Gill Verena A, Hatch Scott A, Boulinier Thierry
Université de Lausanne, Département d'Ecologie Evolution, 1015 Lausanne, Switzerland.
Proc Biol Sci. 2006 Jun 22;273(1593):1551-4. doi: 10.1098/rspb.2005.3457.
Many life-history traits are expressed interactively in life, but to a varying extent on different occasions. Changes in trait expression can be accounted for by differences in the quality of the environment ('environmental constraint' hypothesis) or by strategic adjustments, if the relative contribution of the trait to fitness varies with time ('strategic allocation' hypothesis). In birds, egg production is lower in replacement clutches than in first clutches, but it is unknown whether this reduction results from an environmental constraint (e.g. food being less available at the time when the replacement clutch is produced) or from a strategic allocation of resources between the two breeding attempts. To distinguish between these two hypotheses, we performed an experiment with black-legged kittiwakes (Rissa tridactyla). Pairs were either food-supplemented or not before the first clutch was laid onwards and we induced them to produce a replacement clutch by removing eggs once when the first clutch was complete. As predicted by the 'strategic allocation' hypothesis, egg production of food-supplemented and non-food-supplemented birds decreased between first and replacement clutches. This suggests that kittiwakes strategically reduce investment in egg production for their replacement clutches compared to first clutches.
许多生活史特征在生命过程中以交互方式表现，但在不同情况下程度各异。特征表达的变化可由环境质量差异（“环境限制”假说）来解释，或者如果该特征对适合度的相对贡献随时间变化，则可由策略性调整来解释（“策略性分配”假说）。在鸟类中，替换窝的产蛋量低于第一窝，但尚不清楚这种减少是由于环境限制（例如在产替换窝时食物供应较少）还是由于在两次繁殖尝试之间对资源的策略性分配。为了区分这两种假说，我们对黑脚三趾鸥（Rissa tridactyla）进行了一项实验。在产下第一窝蛋之前开始，对配对的鸟要么提供食物补充，要么不提供，并且当第一窝蛋产完后，我们通过一次性移除蛋的方式诱导它们产替换窝。正如“策略性分配”假说所预测的那样，在第一窝和替换窝之间，提供食物补充和未提供食物补充的鸟的产蛋量都下降了。这表明，与第一窝相比，三趾鸥会策略性地减少对替换窝产蛋的投入。
