The cost of reproduction in the glaucous-winged gull
The cost of reproduction in the glaucous-winged gull
复制标题
灰翅鸥的繁殖成本
作者：
W. Reid
实验性扩大灰翅鸥（Larus glaucescens）的幼仔数量导致成年觅食时间增加，繁殖季节结束时成年体重下降，越冬存活率下降。繁殖成虫的存活率下降与繁殖结束时身体状况下降有关（生殖的生理成本所致）。存活率下降并不是因为在繁殖季节受伤或被捕食的风险增加。育雏大小并没有直接影响在随后的一年中幸存的鸟类的繁殖力。然而，育雏大小可能有一个间接的影响，随后的繁殖力，因为交配损失的可能性增加的鸟类与大的育雏和繁殖性能的鸟类与新的队友减少。根据从繁殖力和存活率计算的寿命适应性估计，具有两个或三个小鸡窝（正常窝数）的鸟类比具有一个或四个小鸡窝的鸟类具有更高的适应性。然而，减少健身的鸟类与四小鸡育雏是轻微的，可能不是一个足够的解释，自然四小鸡育雏的蓝翅鸥。
SummaryExperimental enlargement of brood size in the glaucous-winged gull (Larus glaucescens) resulted in increased adult foraging time, decreased adult body weight at the end of the breeding season, and decreased over-winter adult survival. The decreased survival of breeding adults was associated with reduced body condition at the end of breeding (resulting from physiological costs of reproduction). Decreased survival was not due to an increased risk of injury or predation during the breeding season. Brood size did not directly affect the fecundity of surviving birds in the subsequent year. However, brood size may have an indirect effect on subsequent fecundity because the probability of mate loss increased among birds with large broods and the reproductive performance of birds with new mates was reduced. Based on estimates of life-time fitness calculated from fecundity and survivorship, birds with two- or three-chick broods (the normal brood size) have higher fitness than birds with one- or four-chick broods. However, the decreased fitness of birds with four-chick broods was slight, and probably not a sufficient explanation for the absence of natural four-chick broods in the glaucouswinged gull.