Huck U W, Pratt N C, Labov J B, Lisk R D
Biology Program, Sangamon State University, Springfield, IL 62708.
J Reprod Fertil. 1988 May;83(1):209-14. doi: 10.1530/jrf.0.0830209.
Golden hamsters that were mated repeatedly from 55 days of age produced 6-12 litters. Litter size at birth rose between the 1st and 2nd litters, peaked on the 3rd, and declined steadily after the 5th litter. Offspring sex ratio (% male) at birth followed a similar pattern: increasing between the 1st and 2nd litters, remaining high through the 3rd, and becoming increasingly female-biased thereafter. Weaning success decreased sharply after the 6th litter and most dams failed to raise any young to weaning after the 9th litter. These sequential effects on litter size, offspring sex ratio and weaning success were also observed in females mated once at different ages, but they occurred considerably later in life, i.e. increasing parity hastened the effects of advanced age. These age- and parity-related changes in litter composition are consistent with the Trivers-Willard hypothesis that physiologically-stressed females would skew offspring sex ratios to favour daughters. However, since the observed changes in sex ratio were probably due to differential prenatal mortality, their adaptive significance is unclear.
从55日龄开始反复交配的金黄仓鼠产仔6至12窝。出生时的窝仔数在第1窝和第2窝之间增加，在第3窝达到峰值，并在第5窝后稳步下降。出生时后代的性别比（雄性百分比）遵循类似模式：在第1窝和第2窝之间增加，在第3窝时保持较高水平，此后雌性比例越来越高。第6窝后断奶成功率急剧下降，大多数母鼠在第9窝后未能将任何幼崽抚养至断奶。在不同年龄一次性交配的雌性中也观察到了这些对窝仔数、后代性别比和断奶成功率的连续影响，但它们在生命后期才会出现，即胎次增加加速了高龄的影响。这些与年龄和胎次相关的窝仔组成变化与特里弗斯-威拉德假说一致，即生理压力大的雌性会使后代性别比偏向于雌性。然而，由于观察到的性别比变化可能是由于产前死亡率的差异，其适应性意义尚不清楚。
